ELFH - Pharmacology

Question 1

Which of the following may alter drug response:

Select true or false for each of the following statements.

True
False
A. Tachyphylaxis
B. Changes in receptor number
C. Hypersensitivity reactions
D. Idiosyncratic drug responses
E. Tolerance

Answer 1

True. Tachyphylaxis is defined as a decreased response following a single administration of a drug.

True. Whether this affects drug response depends on the degree of change in receptor number, and whether the drug response involves spare receptors (i.e. a full response is obtained despite some receptors not being occupied).

True. See below

True. Such reactions are not related to known pharmacological properties of a drug (i.e. not a common side effect, they are dose independent). They include anaphylaxis and anaphylactoid reactions.

True. Tolerance is the decreased responsiveness following repeated drug adminsitration.

Question 2

The following processes are mediated by cAMP:

Select true or false for each of the following statements.

True
False
A. Decreased heart rate
B. Liver carbohydrate metabolism
C. Increased contractility
D. Triglyceride breakdown
E. Smooth muscle relaxation

Answer 2

True. Both increases and decreases in heart rate are mediated via cAMP. Beta1-adrenoreceptors are G-protein coupled - their stimulation causes increased cAMP and subsequent tachycardia. Muscarinic M2 receptors are Gi type g-protein coupled receptors and when stimulated decrease cAMP and reduce heart rate via opening of potassium channels

True. Beta2-adrenoreceptors are G-protein coupled, and their stimulation causes increased cAMP and subsequent glycogenolysis (also increases insulin and glucagon secretion).

True. Beta1-adrenoreceptors are G-protein coupled, and their stimulation causes increased cAMP and subsequent increase in contractility.

True. Beta2-adrenoreceptors are G-protein coupled, and their stimulation causes increased cAMP and subsequent lipolysis (also increases insulin and glucagon secretion). Beta 3-adrenoreceptors are also G-protein coupled and increase cAMP - they help regulation lipid metabolism.

True. Beta2-adrenoreceptors are G-protein coupled, and their stimulation causes increased cAMP and subsequent smooth muscle relaxation.

Question 3

Regarding chemical bond strength:

Select true or false for each of the following statements.

True
False
A. Van der Waals > Hydrogen > Ionic > Covalent
B. Covalent > Ionic > Hydrogen > Van der Waals
C. Covalent > Hydrogen > Ionic > Van der Waals
D. Ionic > Covalent > Hydrogen > Van der Waals
E. Van der Waals > Hydrogen > Covalent > Ionic

Answer 3

False.

False.

False.

True.

False.

Ionic bonds involve the electrostatic forces of attraction between oppositely charged ions after the complete loss or gain of electrons and are in general stronger than covalent bonds. Covalent bonds involve the sharing of electrons in order to gain full outer electron shells. Taken in isolation covalent bonds are generally weaker than an ionic lattice, however in complex molecules where there may be double or triple bonding they may become stronger than an ionic bond. For example a single covalently bonded carbon-oxygen required 350KJ/mol to break, but a triple-bonded carbon-oxygen requires 1080KJ/mol to break. A sodium-chloride ionic lattice requires 769KJ/mol to break.

Hydrogen bonding involves the forces of attraction between the postively charged nucleus of a hydrogen atom and an electronegative atom. Electron clouds have no definite shape, therefore at any moment one part of the cloud may be relatively more positively or negatively charged than the other - Van der Waals forces are the forces of attraction / repulsion between such areas.

Question 4

Receptors:

Select true or false for each of the following statements.

True
False
A. Drug affinity depends on the attraction between receptors and drugs
B. Thyroid hormones bind to cell surface receptors
C. Acetylcholine receptors have 2 alpha and 2 beta subunits
D. Midazolam acts at GABAb receptors
E. Nicotinic hormones bind to intracellular receptors

Answer 4

True. Affinity is the ability of a ligand to bind to a specific receptor.

False. They bind to intracellular receptors.

False. The adult acetylcholine receptor has 2 alpha subunits (to which acetylcholine binds), a beta subunit, a delta subunit and an episilon subunit (this is replaced by a gamma subunit in the foetus).

False. It acts at GABAa receptors.

False. Nicotinic receptors are type 1 receptors according to Urquhart’s calssification - membrane bound ligand gated ion channels.

Question 5

Regarding negative exponential processes:

Select true or false for each of the following statements.

True
False
A. The rate of decay varies with time
B. The time constant is longer than the half-life
C. The time constant is the natural logarithm of the half-life
D. Is converted into a straight line by a semi-log plot
E. The time constant is the time for the process to complete if the rate continued at its initial speed

Answer 5

True. In an exponential process the rate of change of a variable is proportional to the magnitude of the variable at that moment in time. In a negative exponential process, the rate of decay is decreasing with increasing time.

True. An exponential process is said to be complete after 3 time constants, as opposed to 5 half-lives.

False. The time constant is the reciprocal of the rate constant.

True. This is true of other exponential processes also. It allows for easier interpretation.

True. It can also be defined as the time taken for an exponential process to fall to 37% or 1/e of its previous value.

Question 6

The following antagonists have agonist properties:

Select true or false for each of the following statements.

True
False
A. Ranitidine
B. Prazosin
C. Pindolol
D. Naltrexone
E. Xameterol

Answer 6

False. It is an H2-receptor antagonist.

False. It is a selective alpha1-adrenoreceptor blocker.

True. It is a non-selective Beta-blocker with partial beta-agonist activity. It also has partial agonist / antagonist activity at the 5-HT1A receptor.

False. It is an opioid receptor antagonist.

True. It is a mixed beta-agonist/antagonist.

Mixed agonist-antagonists are drugs that can exert both agonistic and antagonistic properties. Such drugs include: Opioids (Pentazocine, Nalbuphine and Buprenorphine), Mirtazepine, Pindolol and Xameterol.

Question 7

Receptors and 2nd messengers:

Select true or false for each of the following statements.

True
False
A. G-protein receptors have alpha, beta and delta subunits
B. Insulin receptors are G-protein coupled
C. Opioid receptors are G-protein coupled
D. cAMP is a hydrophobic molecule
E. Nitric oxide acts via cAMP

Answer 7

False. G-proteins consist of alpha, beta and gamma subunits.

False. The Insulin receptor utilises tyrosine kinase.

True.

False. It is hydrophilic.

False. It acts via cGMP.

Question 8

Regarding the log dose-response curve:

Select true or false for each of the following statements.

True
False
A. The ED50 is the drug concentration that induces a response halfway between zero and maximum
B. Therapeutic index = Lethal Dose 50 / Effective Dose 50
C. Drugs with a narrow therapeutic window do not require monitoring
D. It is shifted to the left with the addition of a competitive antagonist
E. Potency is represented by the height of the curve

Answer 8

False. ED50 refers to the dose of drug - this question defines the Effective Concentration 50.

True.

False. Drugs with a narrow therapeutic window often require close monitoring as the risk of reaching toxic levels is greater.

False. The curve is shifted to the right as a higher dose of agonist is required to produce an equivalent response.

False. It is represented by the position of ED50, much like the position of P50 on the oxy-Hb dissociation curve.

Question 9

Antagonists:

Select true or false for each of the following statements.

True
False
A. Have intrinsic activity, but lack affinity
B. Competitive antagonism reduces Emax
C. Competitive antagonists bind to a site distal to the receptor involved
D. Non-competitive antagonism is overcome by increasing agonist dose
E. May also act as agonists

Answer 9

False. They have affinity, but an intrinsic activity of zero.

False. Maximum efficacy (Emax) remains the same, but the dose-response curve is shifted to the right. Non-competitive antagonism reduces Emax

False. Competitive antagonists compete for a receptor with agonists. Non-competitive antagonists bind to a distal site, and induce a change at the receptor.

False. This is competetive antagonism.

True. Mixed agonists-antagonists can act as agonists at some receptors and antagonists at others e.g. pentazocine.

Question 10

Partial agonists:

Select true or false for each of the following statements.

True
False
A. Act as both agonists and antagonists
B. Have similar intrinsic activity to full agonists
C. Include buprenorphine
D. Include pentazocine
E. Include clozapine

Answer 10

True. Partial agonists act as agonists in isolation, but can act antagonistically when given in combination with a full agonist.

False. Full agonists have an intrinsic activity of 1, whereas a partial agonists have an intrinsic activity of <1.

True.

False. Pentazocine is a mixed agonist-antagonist.

True. Clozapine is a partial agonist at D2 receptors.

Question 11

The following are true regarding Volume of Distribution (Vd):

Select true or false for each of the following statements.

True
False
A. It is the amount of drug that distributes following administration
B. Can be greater than total body water
C. Is measured in kg/L
D. Is a constant for a given drug
E. Is equal to Clearance divided by Time Constant

Answer 11

False. It is the volume that a drug distributes into following administration.

True. TBW = 42L whilst Vd can be up to 1000L.

False. It is measured in L/Kg.

True.

False. Vd = Clearance x Time Constant.

Question 12

Context sensitive half-time:

Select true or false for each of the following statements.

True
False
A. Is a decrement time
B. Shares a constant relationship with elimination half-life
C. Varies with duration of drug infusion
D. Is reliably used to describe time for recovery
E. Reflects the combined effects of absorption and distribution

Answer 12

True. Decrement time = the time taken of the plasma level for a drug to fall to a specified value (Context-Sensitive Half-Time is 50%).

False. There is no such relation.

True. This is the ‘context’.

False. It is the time for the plasma levels to fall to 50% of the value when the infusion is stopped.

False. It reflects the combined effects of distribution and metabolism.

Question 13

The following influence Volume of Distribution (Vd):

Select true or false for each of the following statements.

True
False
A. Regional blood flow
B. Lipid solubility
C. Degree of tissue protein binding
D. Degree of plasma protein binding
E. Degree of ionisation

Answer 13

True.
True.
True.
True.
True.

Question 14

Infusion kinetics:

Select true or false for each of the following statements.

True
False
A. It takes 5 half-times to reach steady state concentration
B. Steady state volume of distribution is dependent on lipid solubility and molecular weight
C. Loading Dose = Vd x Desired Plasma Concentration
D. Maintenance Dose = Steady State Vd x Clearance
E. Clearance = Input (mg/min) x Plasma Concentration (mg/ml)

Answer 14

False. It takes 5 Half-lives to reach steady state concentration.

False. Steady state volume of distribution is dependent on lipid solubility and clearance.

True.

False. Maintenance Dose = Steady State Concentration x Clearance.

False. In infusion kinetics at steady state Input = Elimination

Input (mg/min) is therefore equal to Clearance (ml/min) x Plasma Concentration (mg/min). Therefore:

Clearance = Input (mg/min) / Plasma Concentration (mg/ml)

Question 15

The following statements are true of Cytochrome P450 enzyme isoforms:

Select true or false for each of the following statements.

True
False
A. CYP2E1 is involved in metabolism of paracetamol
B. CYP3A4 is involved in metabolism of phenytoin
C. Are only found in the liver
D. Account for most phase 2 reactions
E. CYP2E1 is involved in the metabolism of chloride containing volatile agents

Answer 15

True.

False. CYP3A4 is important in the metabolism of both midazolam and alfentanil.

False. CYP2E1 is found in the kidneys.

False. Account for most phase 1 reactions.

False. CYP2E1 is involved in the metabolism of fluoride containing volatile agents.

Question 16

The following are enzyme inducers:

Select true or false for each of the following statements.

True
False
A. Rifampicin
B. Metronidazole
C. Acute alcohol use
D. Carbamazepine
E. Chloramphenicol

Answer 16

True.

False. It is an enzyme inhibitor.

False. Acute alcohol use inhibits whilst chronic use induces.

True.

False. It is an enzyme inhibitor.

Question 17

Phase 2 reactions include:

Select true or false for each of the following statements.

True
False
A. Oxidation
B. Acetylation
C. Sulphation
D. Hydrolysis
E. Glucuronidation

Answer 17

False. This is a Phase I reaction.
True.
True.
False. This is a Phase I reaction.
True.

Question 18

Elimination:

Select true or false for each of the following statements.

True
False
A. Can only be by either distribution or metabolism
B. In 1st order kinetics, half-life is constant
C. In 1st order kinetics, a constant amount of drug is eliminated per unit time
D. Zero order kinetics is a linear process
E. In zero order kinetics, half-life increases with dose administered

Answer 18

False. Can also be by excretion.
True.
False. A constant proportion is eliminated per unit time.
False. Zero order kinetics is also known as non-linear kinetics.
True.

Question 19

Hepatic clearance:

Select true or false for each of the following statements.

True
False
A. A drug with a high extraction ratio is not affected by protein binding
B. Lignocaine is an example of an enzyme limited drug
C. High extraction ratio implies significant 1st pass metabolism
D. Enzyme induction / inhibition can profoundly affect the clearance of drugs with a low extraction ratio
E. Warfarin is an example of an enzyme limited drug

Answer 19

True. It is not affected by enzyme level either.

False. Lignocaine has a high extraction ratio (>0.7) and is therefore flow / perfusion limited (as opposed to enzyme / capacity limited).

True. Most of the drug is extracted on the first pass through the liver, hence why changes in hepatic blood flow can drastically affect clearance.

True. Drugs with a low extraction ratio are enzyme / capacity limited drugs.

True. As are phenytoin, theophylline and most benzodiazepines and barbituates.

Question 20

Bioavailability:

Select true or false for each of the following statements.

True
False
A. Of drugs administered via the IV route can be as high as 90%
B. Is the fraction of administered drug that reaches systemic circulaiton
C. Glycopyrrolate has >80% bioavailability
D. Is influenced by genetics
E. Is influenced by circadian rhythm

Answer 20

False. IV drug administration provides 100% bioavailability.

True.

False. Glycopyrrolates bioavailability is < 5%.

True. There are phenotypic variations in bioavailability.

True.

Question 21

Isoflurane:

Select true or false for each of the following statements.

True
False
A. Is a stereoisomer of enflurane
B. Causes vasodilatation without reflex tachycardia
C. Has a saturated vapour pressure of 23.3 kPa at 20 degrees Celcius
D. 0.2% of isoflurane undergoes hepatic metabolism
E. The chloride group is attached to the chiral centre

Answer 21

False. It is a structural isomer.

False. A reflex tachycardia suggests that baroreceptor function remains intact with isoflurane use. The main cause of isoflurane induced hypotension is a reduction in systemic vascular resistance. Myocardial function and cardiac output see only a small decrease.

False. This is the SVP of enflurane. The SVP of isoflurane is 32 kPa.

True. Hepatic cytochrome P450 metabloizes the C - F bond. Renal toxicity is rare due to the low levels of fluoride ions produced.

True.

Question 22

Factors that increase Minimum Alveolar Concentration:

Select true or false for each of the following statements.

True
False
A. Alpha-2 agonists
B. Hypernatraemia
C. Chronic alcohol intake
D. Acute alcohol intake
E. The premature neonatal period

Answer 22

False. These decrease MAC.

True.

True.

False. Acute alcohol intake decreases MAC.

False. The MAC is low in preterm neonates. For most agents MAC value peaks at 1-6 months.

Question 23

Sevoflurane:

Select true or false for each of the following statements.

True
False
A. Has a chiral centre
B. Produces hydrofluoric acid if stored in glass
C. Has a blood:gas coefficient of 1.4
D. Causes coronary steal syndrome
E. Is metabolised by cytochrome isoform CYP3A4

Answer 23

False. It is achiral

True. This is highly toxic. Lewis acids degrade the ether and halogen bonds if sevoflurane is stored in water at concentrations less than 100ppm. The highly toxic hydrofluoric acid corrodes glass, driving Lewis acid production.

False. This is the blood:gas coefficient of isoflurane. 0.7 is the correct answer.

False. This is a side effect of isoflurane use.

False. This cytochrome isoform is responsible for the metabolism of opiates and benzodiazepines. CYP2E1 is responsible for sevoflurane / isoflurane / halothane metabolism.

Question 24

Sevoflurane:

Select true or false for each of the following statements.

True
False
A. Is methyl-ethyl ether
B. Inhibits pulmonary vasoconstriction
C. Undergoes renal metabolism to produce inorganic fluoride ions
D. Compound A production is more likely in the presence of dry potassium hydroxide
E. Has a molecular weight higher than halothane

Answer 24

False. It is a polyfluorinated methyl isopropyl ether.

True.

False. This was a feature of methoxyflurane. 3.5% of sevoflurane undergoes hepatic metabolism to produce hexafluroisopropanol and fluoride ions.

True. The suggested nephrotxoic threshold for compound A is 150-200ppm. These are levels that far exceed what is seen in clinical practice.

True. Sevoflurane 200.1, Halothane 197, Isoflurane / Enflurane 184.5, Desflurane 168, Xenon 131 and N2O 44.

Question 25

Minimum alveolar concentration: Select true or false for each of the following statements. True False A. Is above 6% for desflurane B. Is above normal atmospheric pressure for nitrous oxide C. May be as low as 0.7 for sevoflurane in 70% nitrous oxide D. Is 0.95 for Halothane E. Is lower for enflurane than it is for isoflurane

Answer 25

True. True. True. False. MAC of halothane is 0.75 False. Isoflurane 1.17, Enflurane 1.68

Question 26

Halothane: Select true or false for each of the following statements. True False A. Is an halogenated ether B. Has a SVP at 20 degrees celcius, similar to isoflurane C. May be given safely with adrenaline infiltration at doses of 100 micrograms per minute D. Its C-Br bonds are metabolised with greater ease than its C-F bonds E. Is metabolised under hypoxic conditions to produce trifluoroacetyl chloride which is implicated in halothane hepatitis

Answer 26

False. Halothane is a halogenated hydrocarbon. There is no ether 'link'. True. Halothane 32.3 kPa, Isoflurane 33.2 kPa. False. This dose of adrenaline should be administered over a 10 minute period. Halothane sensitises the heart to catecholamines, which may lead to arrhythmias - particularly ventricular tachycardias and bradyarrhythmias. True. C-F bonds are the most stable carbon-halogen bond. False. This metabolite is produced under oxidative conditions. In a hypoxic state reduced metabolites are produced e.g. inorganic fluoride.

Question 27

Desflurane: Select true or false for each of the following statements. True False A. Has a boiling point of 39 degrees celcius B. Is administered via the Tec 5 vaporiser C. Induces tachycardia and hypertensions at MAC values greater than 1 D. Produces carbon monoxide on contact with soda lime E. Has a blood gas coefficient higher than nitrous oxide

Answer 27

False. Its boiling point is 23.5 degrees celcius. False. Is administered via the Tec 6. This heats the volatile to 39 degrees celcius under a pressure of 2 atmospheres. True. True. Volatile agents that contain a -CHF2 molecule (isoflurane, enflurane, desflurane) may produce carbon monoxide upon reaction with dry soda lime. False. Blood gas coefficient of desflurane is 0.42; nitrous oxide 0.47

Question 28

Nitrous Oxide Select true or false for each of the following statements. True False A. Has a critical pressure of 72 bar B. Is stored in cylinders with a pin index configuration of 2 and 5 C. Increases cerebral blood flow D. Inhibits methionine synthetase by reducing the cobalt ion in vitamin B12 E. Reduces that MAC of isoflurane to 0.5 when used at 70%

Answer 28

True. In addition to this, the critical temperature is 36.5 degrees celcius. False. This is the pin index of oxygen. The configuration for nitrous oxide is 3 and 5. True. It may also increase intracranial pressure. False. It oxidises this cobalt ion. It may also inhibit methionine synthetase directly. Nitrous oxide therefore inhibits methionine, thymidine, tetrahydrofolate and DNA synthesis. True.

Question 29

Halothane: Select true or false for each of the following statements. True False A. Increases cerebral blood flow less than enflurane B. Has a sweet odour C. Has two bromide atoms D. Is prepared with 0.01% thymol to prevent combustion E. Causes vagal stimulation

Answer 29

False. In descending order; halothane, enflurane, nitrous oxide, isoflurane True. False. 1 bromide, 1 chloride and 3 fluoride ions. False. It is prepared with 0.01% thymol to prevent decomposition by light. True. It may also cause bradycardia by inhibiting atrioventricular conduction / activity.

Question 30

In reference to inhaled anaesthetic agents: Select true or false for each of the following statements. True False A. Isoflurane does not increase cerebral blood flow at concentrations below 1 MAC B. Xenon is hepatically metabolised C. Oxygen has a critical pressure of 50 bar D. Entonox seperates into its constituent parts below 7 degrees celcius E. 0.1% of nitrous oxide is metabolised

Answer 30

True. False. All clearance is by lung elimination. True. False. This is likely to occur at temperatures below -7 degrees celcius (pseudo-critical temperature) at pressures of 117 bar. False. Less than 0.01% of nitours oxide undergoes metabolism.

Question 31

Propofol: Select true or false for each of the following statements. True False A. Is highly protein bound B. Produces vasodilatation by nitric oxide production C. Is only partly unionized at physiological pH D. Has a hydroxyl group situated on its 4th carbon E. Undergoes both phase 1 and phase 2 metabolism

Answer 31

True. 97% protein bound. True. Propofol causes hypotension (reduction in sytsemic vascular resistance and cardiac output) without tachycardia. Bradycardia is common, especially with opiate co-administration. False. The pka of propofol is 11, therefore at pH 7.4 it is almost entirely unionized. False. The hydroxyl group is situated on the 1st carbon. Phase 1 metabolism into a quinol derivative involves hydroxylation of the 4th carbon. True. Glucuronidation is the predominant metabolic pathway, hydroxylation by cytochrome P450 to a quinol derivative prior to conjugation is also an important pathway. The relative importance of each pathway varies amongst patients.

Question 32

Propofol: Select true or false for each of the following statements. True False A. Is used at a dose of around 4 mg/kg for IV paediatric induction B. Causes a reduction in cardiac output solely by reducing heart rate C. Clearance is by hepatic metabolism alone D. Acts as an anti-emetic by competitive antagonism of central serotonin receptors situated in the chemoreceptor trigger zone E. Is a cause of hypertrigylcerideaemia

Answer 32

True. Approx double the typical adult dose. False. Propofol also reduces myocardial contractility and sympathetic tone. False. Extra-hepatic metabolism is significant, suggested by the fact that clearance is higher than hepatic bolod flow. Sites for extra-hepatic metabolism include the kidneys (responsible for about a third of extra-hepatic metabolism) and lungs (to 2, 6 - diisopropyl - 1, 4 - quinol). False. The anti-emetic effect of propofol is probably mediated through dopamine receptor antagonism. True. This may be a part of the metabolic syndrome seen in children after prologed infusion. Propofol infusions have been linked to organ fatty infiltration with severe bradycardias, metabolic acidosis and increased mortality.

Question 33

With regards to IV induction agents: Select true or false for each of the following statements. True False A. Propofol has the same volume of distribution as ketamine B. Propofol has the highest clearance rate C. The clearance rate of etomidate is 5 ml/kg/min D. Thiopentone has a higher percentage of protein binding that methohexitone E. Thiopentone has a pKa of 10.6

Answer 33

False. Propofol 4 L/kg. Ketamine 3 L/kg. Etomidate 3 L/kg. Thiopentone 2.5 L/kg. True. 30-60 ml/kg/min. False. Etomidate 10-20 ml/kg/min, Ketamine 17 ml/kg/min, Thiopentone 3.5 ml/kg/min True. Thiopentone 80%. Methohexitone 60%. False. pKa of thiopentone is 7.6

Question 34

Midazolam: Select true or false for each of the following statements. True False A. Is 68% protein bound B. Is 40% unionized at physiological pH C. Has inactive metabolites D. Is metabolised by the same cytochrome P450 system as alfentanil E. Is given in oral doses of up to 1 mg/kg in paediatric premedication

Answer 34

False. 98% protein bound. False. Midazolam is a tautomeric molecule consisting of benzene and diazepine rings. In a pH > 4 the diazepine ring closes producing a lipid soluble unionized molecule. With a pKa of 6.5 around 89% of molecules are unionized at physiological pH. False. The phase 1 metabolite 1-alpha-hydroxy-midazolam is active. This may then be conjugated (glucuronidation) prior to excretion. True. CP450 3A3/4. The action of midazolam may be prolonged by co-administration of alfentanil. True. 30 minues prior to induction. Monitoring is required if doses >0.5 mg/kg are used.

Question 35

Ketamine: Select true or false for each of the following statements. True False A. Is a competitive antagonist of NMDA receptors B. Is prepared as a racemic mixture in which the R- isomer is more potent than the S+ C. Is used as an oral premedication in doses of 2-5 mg/kg D. Emergence phenomena is less common in the young and elderly E. Undergoes cytochrome P450 de-methylation to the inactive metabolite norketamine

Answer 35

False. Non-competitive antagonist. False. S+ is 2-3 times more potent than the R- isomer. It may also produce less intense emergence phenomena. True. 20% bioavailability. Doses of up to 10 mg/kg have be used in extreme cases. True. False. Norketamine is active, this then undergoes glucuronidation to an inactive metabolite which is excreted.

Question 36

Ketamine: Select true or false for each of the following statements. True False A. Is stored as an acidic solution B. Induces dissociative anaesthesia with predominant beta activity on EEG C. Reduces cerebral oxygen consumption D. Is 25-50% protein bound E. Is a direct myocardial depressant

Answer 36

True. pH 3.5-5.5. Ampoules can contain 10, 50 or 100 mg/ml. False. Theta and delta activity is pre-dominant during ketamine induced dissociative anaesthesia. False. Cerebral oxygen consumption, blood flow and intracranial pressure are all increased by ketamine. True. True. Ketamine increases sympathetic tone and circulating levels of adrenaline and noradrenaline. This produces the cardiovascular effects seen clinically of tachycardia, increased cardiac output, increased / maintained blood pressure and elevated CVP. However, ketamine also produces a mild direct myocardial depressant effect that is masked, less so for the S+ isomer.

Question 37

Etomidate: Select true or false for each of the following statements. True False A. Is prepared with 35% propylene glycol B. Produces pain on injection in 75% of cases C. Causes nausea and vomiting D. Is given as an IV induction dose of 2-3 mg/kg E. Produces excitatory movements with epileptiform activity on EEG

Answer 37

True. False. Produces pain in around only 25%. True. False. The IV induction dose is 0.2-0.3 mg/kg True. Etomidate is the most likely IV induction agent to cause myoclonic movements and epileptiform activity on EEG - in around 20% of cases.

Question 38

Etomidate: Select true or false for each of the following statements. True False A. Has an ester bond B. May be used in patients with porphyria C. Is predominanlty protein bound D. Inhibits adrenal medullary function E. Has the same volume of distribution as ketamine

Answer 38

True. Etomidate is an imidazole derivative and an ester. False. Etomidate is known to cause a porphyric crisis. True. Around 75%. False. Etomidate has been shown to inhibit 11-beta and 17-alpha hydroxylase function and impair aldosterone and cortisol synthesis for up to 24 hours after administration. Steroidogenesis occur in the adrenal cortex. True. 3 l/kg

Question 39

Thiopentone: Select true or false for each of the following statements. True False A. Is prepared as a hygroscopic yellow powder in 8% sodium carbonate B. When reconstitued with water produces a 2.5% solution C. At physiological pH 60% of the drug is unionized in blood D. Is metabolised to pentobarbitone E. When in solution is found predominantly in its keto form

Answer 39

False. 6% sodium carbonate. True. True. True. Pentobarbitone is an active metabolite. False. It is predominantly in its enol form when in solution. The enol form is soluble. Thiopentone is tautomeric and alkaline conditions promote the switch from keto to enol.

Question 40

Thiopentone: Select true or false for each of the following statements. True False A. Has a sulphur group on its 2nd carbon B. Is a bronchodilator C. Stimulates anti-diuretic hormone release D. Is an enzyme inhibitor E. Is more active in alkalotic conditions

Answer 40

True. There is an oxygen group in this position in oxybarbiturates. False. Thiopentone may produce laryngospasm and bronchospasm. True. This is one of the reasons why thiopentone causes a reduction in urine output. False. Thiopentone is an enzyme inducer. False. Acidosis and hypoalbuminaemia increases the amount of free unionized drug. A lower dose is often needed in critically ill patients.

Question 41

Remifentanil: Select true or false for each of the following statements. True False A. Undergoes hepatic metabolism B. Has a half life of approximately 20 minutes C. Has a short duration due to rapid redistribution D. Has a potency similar to fentanyl E. Has a prolonged action in patients with pseudocholinesterase deficiency

Answer 41

False. Remifentanil is broken down by non-specific tissue and plasma esterases to remifentanil acid which is essentially inactive. False. The context-sensitive half-life of remifentanil is 3 minutes and is not significantly altered with duration of infusion. False. Due to the high clearance and relatively small volume of distribution (steady state volume of distribution of 350 ml/kg), Remifentanil has a short terminal elimination half-life of 3-10 minutes, consistent with its context sensitive half life of 3-6 minutes. Therefore the duration of action of remifentanil is dependent on elimination rather than redistribution. True. False. Remifentanil is not metabolised by plasma cholinesterase (psuedocholinesterase) and therefore its duration of action is the same in patients with pseudocholinesterase deficiency.

Question 42

The pharmacological effects of Morphine include: Select true or false for each of the following statements. True False A. Constipation B. Biliary spasm C. Histamine release D. Cough E. Release of antidiuretic hormone

Answer 42

True. True. True. Morphine can be used as a positive control for skin-prick testing due to its local histamine release. False. Morphine is a cough suppressant. Its derivative, codeine is used in cough suppressant medications. True.

Question 43

Fentanyl: Select true or false for each of the following statements. True False A. Has a potency 10 times that of morphine B. Is highly water-soluble C. Has a large volume of distribution D. Does not accumulate even after repeated doses E. Is metabolised to norfentanyl

Answer 43

False. Fentanyl has a potency approximately 100 times that of morphine. False. Fentanyl is highly lipid soluble. It is poorly soluble in water. True. Its lipid solubility gives fentanyl a large volume of distribution of 4 L/kg. False. Because of its large volume of distribution, fentanyl accumulates with repeated doses and has a variable context-sensitive half-life. True. Fentanyl is N-demethylated to norfentanil and then hydroxylated for renal excretion. All metabolites are inactive.

Question 44

Diclofenac: Select true or false for each of the following statements. True False A. Works by inhibiting lipo-oxygenase B. May increase renal blood flow C. Has anti-pyretic properties D. Reversibly promotes platelet aggregation E. May be used in the last trimester of pregnancy

Answer 44

False. Diclofenac is a Non-Streroidal Anti-inflammatory and therefore works by inhibiting COX (Cyclo-oxygenase) in a non-specific manner. False. Prostaglandins formed from COX action on Arachidonic Acid are involved in the autoregulation of renal blood flow. Reduction of PGE synthesis by Diclofenac can reduce renal blood flow in some susceptible individuals. True. Prostaglandins also regulate body temperature within the hypothalamus. Inhibition of prostaglandin synthesis reduces body temperature. False. COX produces Thromboxane A2 which causes platelet aggregation. It also produces PGI2 in vascular endothelium which inhibits platelets. However the overall action of COX inhibition by diclofenac is to reduce platelet aggregation as its effect on Thromboxane A2 production is greater than its effect on PGI2 production. False. Use of NSAIDs in pregnancy can lead to premature closure of the ductus arteriosus and therefore Diclofenac is not used in pregnancy. It is notable that low-dose aspirin is used in pregnancy and is now recommended in the primary prevention of pre-eclampsia in patients considered at high risk (eg Type I diabetes, previous pre-eclampsia).

Question 45

Alfentanil: Select true or false for each of the following statements. True False A. Is more lipid soluble than pethidine B. Is less lipid soluble than fentanyl C. Is highly protein bound D. Is more potent than fentanyl E. Has clinically important active metabolites

Answer 45

True. True. Alfentanil is more lipid soluble than pethidine but less than fentanyl. True. Alfentanil is 85-92% protein bound, mainly to alpha-1 glycoprotein. False. Potency is a measure of drug activity expressed as the amount of drug required to give a certain clinical effect. Alfentanil works quickly due to its pKa of 6.5, leaving it almost all unionized and therefore available to cross membranes and work at its effector site immediately. However, if time to effect is excluded, less fentanyl is required for the same clinical effect as alfentanil and therefore it is less potent than fentanyl. False. Alfentanil is metabolised by CYP3A3/4 which also metabolises midazolam (therefore if used together in large enough doses, they will prolong each others' elimination half life). The product of metabolism is noralfentanil which is inactive.

Question 46

Tramadol: Select true or false for each of the following statements. True False A. Is a controlled drug B. Can be administered intravenously C. Has affinity for binding at the mu opoid receptor comparable to that of morphine D. Acts predominantly by inhibiting the reuptake of noradrenaline and serotonin (5-HT) E. May be used concurrently with a MAOI

Answer 46

True. True. False. It has weak affinity for the mu opoid receptor of 2.1 micromolar compared with 0.0003 micromolar for morphine. True. Whilst it is a mu agonist, it also acts as a serotonin and noradrenaline re-uptake inhibitor, NMDA antagonist and nicotinic/muscarinic Acetylcholine receptor antagonist. Its main analgesic effect is due to the inhibition of NA and 5HT reuptake. False. Tramadol's serotonergic modulating activities mean that patients are more susceptible to serotonin crisis if used with MAOIs or SSRIs.

Question 47

The metabolism of morphine involves: Select true or false for each of the following statements. True False A. Acetylation B. Demethylation C. Oxidation D. Methylation E. Conjugation with glucouronide

Answer 47

False. True. True. True. True. Morphine metabolism involves demethylation, oxidation and conjugation with glucuronide. Some morphine is methylated to codeine. 70% of morphine forms Morphine 3-Glucuronide, a mu receptor antagonist. 30% becomes Morphine 6-Glucuronide which is 13 times more potent than morphine. These metabolites are excreted by the kidneys and can accumulate in renal failure. Therefore care is required with dosing in patients with significant renal impairment.

Question 48

Clonidine: Select true or false for each of the following statements. True False A. Is predominantly an alpha-1 adrenergic agonist B. Is poorly absorbed orally C. Lowers the MAC of volatile anaesthetic agents D. Attenuates the stress response to endotracheal intubation E. Can be used for spinal analgesia

Answer 48

False. Clonidine has a 200 fold higher affinity for the alpha-2 adrenoceptor than the alpha-1 adrenoceptor and is an agonist at the alpha-2 adrenoceptor. False. It is very well absorbed orally with a bioavailability of 100% and an onset time of 30 minutes and reaching a peak plasma level around 60-90 minutes. True. It acts on alpha-2 adrenoceptors in the lateral reticular formation to reduce the MAC of volatiles and central Sympathetic Nervous System (SNS) outflow. It also acts in the spinal cord to increase endogenous opoid and increase descending pathway inhibition (gate theory of pain). True. True. It can be used via the intrathecal or epidural route.

Question 49

The following drugs are antagonised by naloxone: Select true or false for each of the following statements. True False A. Bupranorphine B. Dextropropoxyphene C. Etomidate D. Midazolam E. Remifentanil

Answer 49

True. True. Dextropropoxyphene is an opoid (contained in Co-proxamol). False. False. Midazolam is a benzodiazepine. True.

Question 50

The following statements are true: Select true or false for each of the following statements. True False A. Paracetamol is oxidised to N-acetyl P-Benzoquinoneimine (NAPQI) B. Paracetamol is antagonised by N-Acetyl Cysteine (NAC) C. Paracetamol reduces prostaglandin synthesis D. Aspirin overdose causes a metabolic alkalosis E. Aspirin reversibly inhibits cyclooxygenase

Answer 50

True. NAPQI is a potent cell toxin. 10% of paracetamol is oxidised to NAPQI which is usually safely conjugated with glutathione. If glutathione is depleted, as in paracetamol overdose, it bonds to exposed protein SH groups causing inactivation and cell necrosis in a centrilobular pattern. False. NAC replaces glutathione to allow safe metabolism of paracetamol. True. Paracetamol reduces the COX enzyme to reduce prostaglandin synthesis. False. Aspirin (Salicylic acid) causes a metabolic acidosis and respiratory alkalosis in adults. It is an acid in itself and promotes hyperventilation by a direct effect. False. Aspirin irreversibly inhibits COX and therefore its effects on platelets last until the platelet is replaced as platelets do not have a nucleus and therefore lack capacity to produce new COX enzymes.

Question 51

Plasma cholinesterase: Select true or false for each of the following statements. True False A. Acquired deficiencies of the enzyme in genotypically normal patients prolongs suxamethonium activity for several hours B. The commonest genotype for cholinesterase activity is Eu:Eu C. Deficiency occurs in pregnancy D. Homozygotes always experience a prolonged suxamethonium block E. Patients who are homozygotes for the fluoride resistant gene have a near normal dibucaine number

Answer 51

False. The prolongation of action in genotypically normal patients, i.e. with acquired deficiencies of the enzyme, is usually no longer than 30 minutes. True. Eu:Eu is the commonest genotype and it is present in 96% of the population. These homozygotes have a completely normal recovery from suxemethonium. True. Pregancy is an acquired factor associated with reduced plasma cholinesterase deficiency. Other causes are Liver disease, Renal and Cardiac Failure, Thyrotoxicosis, Cancer and a number of drugs. False. Eu:Eu is a homozygote. True. Their dibucaine number is around 70 (compared with 80 for Eu homozygotes). Dibucaine is an amide local anaesthetic. The dibucaine number indicates the percentage that it inhibits the various forms of plasma cholinesterase. The normal Eu Eu genotype is most inhibited (80%), Ea Ea and Es Ea genotypes are least inhibited (20%). The silent gene homozygotes Es Es have no plasma cholinesterase activity to inhibit and so do not have a dibucaine number.

Question 52

Contraindications to suxemethonium include: Select true or false for each of the following statements. True False A. The presence of renal failure B. 48 hours following major burns C. Malignant hyperpyrexia D. Pregnancy E. Day case anaesthesia

Answer 52

False. Renal failure does not itself cause a hyperkalaemic response to suxemethonium, however hyperkalaemia secondary to acute renal failure would increase the risk of arrhythmias. True. Burns patients (>10% of body surface) are at greatest risk of suxemethonium induced hyperkalaemia from 24 hours after the injury until around 18 months. True. Along with all the volatile inhalational agents. False. Though it's action may be slightly prolonged. False.

Question 53

Malignant hyperthermia: Select true or false for each of the following statements. True False A. Exhibits autosomal recessive inheritance B. Is associated with a defect on the ryanodine receptor encoded on chromosome 19 C. Diagnosis is based on response of biopsied skeletal muscle to 2% halothane and cafffeine (2mmol/L) D. Without dantrolene the mortality can be as high as 70% E. Each vial of dantrolene reconstituted with 60ml water produces a solution of pH 8.0

Answer 53

False. MH is a rare autosomal-dominant condition. Incidence in UK 1 in 200,000. True. True. True. False. Dantrolene is available as capsules and in vials as an orange powder containing 20 mg dantrolene, 3 g mannitol and sodium hydroxide. Each vial when reconstituted with 60 ml water has a pH of 9.5.

Question 54

Safe drugs in malignant hyperthermia include: Select true or false for each of the following statements. True False A. Propofol B. Fentanyl C. Ketamine D. Etomidate E. Nitrous Oxide

Answer 54

True. True. True. True. True. Sumemethonium and all volatile anaesthetic agents are the only triggers of MH.

Question 55

The effects of non-depolarising musle relaxants are prolonged by: Select true or false for each of the following statements. True False A. Volatile anaesthetics B. Hyperthermia C. Lithium D. Calcium channel antagonists E. Hypomagnesaemia

Answer 55

True. False. Action is prolonged by hypothermia. True. True. There is a reduced calcium influx resulting in reduced ACh release. False. Effects are prolonged by hypermagnesaemia due to the decrease in ACh release caused by competition with calcium and by stabilization of the post juntional membrane. Effects are also prolonged by aminoglycoside antbiotics, such as gentamicin or tobramycin.

Question 56

Atracurium: Select true or false for each of the following statements. True False A. Has 4 chiral centres and 10 stereoisomers B. Undergoes Hofmann elimination accounting for 60% of its metabolism C. Hofmann elimination is potentiated by acidosis and hypothermia D. A product of its metabolism is laudanosine, a glycine antagonist E. Laudanosine is a breakdown product of both ester hydrolysis and Hofmann degradation.

Answer 56

True. False. Hofmann elimination only accounts for 40% of atracurium's metabolism. False. Acidosis and hypothermia will slow down the process of Hofmann elimination. True. True.

Question 57

Cis-atracurium: Select true or false for each of the following statements. True False A. Is one of the 10 stereoisomers present in atracurium B. Is 10 times more potent than atracurium C. Is predominantly eliminated by ester hydrolysis D. Is safe for use in patients with renal failure E. Has metabolites with neuromuscular blocking properties

Answer 57

True. False. It is approximately 3 to 4 times more potent than atracurium. False. It is predominantly eliminated by Hofmann elimination and its metabolites have no neuromuscular blocking properties. True. It can be used safely in both renal and hepatic failure. False. It is predominantly eliminated by Hofmann elimination and its metabolites have no neuromuscular blocking properties.

Question 58

The following are benzylisoquinolinium compounds: Select true or false for each of the following statements. True False A. Atracurium B. Midazolam C. Pancuronium D. Tubocurarine E. Mivacurium

Answer 58

True. False. Midazolam is a benzodiazepine. False. Pancuronium is an aminosteroidal compound. True. True.

Question 59

Other effects of suxemethonium: Select true or false for each of the following statements. True False A. Sinus or nodal bradycardia secondary to sympathetic ablation B. Myalgia, particularly in young women C. Patients with severe burns or neuromuscular disorders are susceptible to sudden, massive release of potassium D. Can cause a rise in intra-occular pressure by about 10mmHg for a matter of minutes following administration E. Raises intragastric pressure by 10 cmH2O

Answer 59

False. Sinus or nodal bradycardia is caused via stimulation of muscarinic receptors in the sinus node. True. Muscle pains are commonest in young females mobilizing rapidly in the post operative period. True. May be large enough to provoke cardiac arrest. True. Normal intraocular pressure is 10-15 mmHg making this a 100% rise in intra-ocular pressure which can be significant in the presence of globe perforation. True. Though suxemethonium simultaneously increases lower oesophageal sphincter tone so there is no increased risk of reflux.

Question 60

Vecuronium: Select true or false for each of the following statements. True False A. Is relatively cardio-stable B. Is presented as a powder containing mannitol and sodium hydroxide. C. May cause critical illness myopathy D. Precipitates histamine release E. Its chemical structure differs from pancuronium by a single methyl group

Answer 60

True. The aminosteroids are not assocciated with the histamine release seen with the benzylisoquinolinium compounds. True. It is unstable in solution and therefore presented as a freeze-dried powder containing mannitol and sodium hydroxide. True. As can all musle relaxants if used long term. False. True.

Question 61

Esmolol: Select true or false for each of the following statements. True False A. Is useful in the treatment of essential hypertension B. Has a half life of 2 minutes C. Is largely excreted unchanged in the urine D. Acts selectively on beta-1 receptors E. Possesses intrinsic sympathomimetic activity

Answer 61

False. It is only given intravenously and has a short half life. False. It is around 10 minutes. False. It is rapidly metabolised by red-cell esterases. False. It is non-selective. False.

Question 62

The following statements about selective phosphodiesterase (PDE) inhibitors are true: Select true or false for each of the following statements. True False A. Inhibition of isoenzyme family No. I effects a positive inotropic action B. Inhibition of isoenzyme family No. III results in clinically important bronchodilatation C. They increase myocardial oxygen consumption D. Tachycardia is a common occurrence E. Their use increases hblood pressure as a result of increased cardiac output and systemic vascular resistance.

Answer 62

False. Inhibition of isoenzyme family No. III results in positive inotropy. False. Bronchodilatation does occur but not to a clinically significant degree. False. There is unchanged or even slightly reduced myocardial oxygen consumption as systemic vasodilation reduces left ventricular systolic wall tension. True. There is a reflex tachycardia. False. Hypotension is often seen as a result of reduced systemic vascular resistance due to smooth muscle relaxation.

Question 63

Milrinone: Select true or false for each of the following statements. True False A. Is one of the bipridine derivative group of phosphodiesterase inhibitors. B. Is structurally related to amrinone C. It's short half life makes it well suited to use as an infusion D. Doses should be reduced in end stage renal failure E. Is incompatible with intravenous frusemide when given through the same cannula

Answer 63

True. Enoximone and piroximone are imidazolone derivatives. False. False. It is used in infusion form but has a terminal half life of 2.5 hours. A loading dose is required. True. 80% is excreted unchanged via the kidneys and dose reductions are required when the creatinine clearance falls to less than 30 ml/min. True.

Question 64

Clonidine: Select true or false for each of the following statements. True False A. Is a selective partial agonist for the alpha-2 adrenoceptor with a ratio of approximately 200:1 (alpha2:alpha1) B. Is rapidly absorbed when given orally C. When given as premedication, it reduces the MAC by up to 50% D. Discontinuation can result in hypertension E. Has a diuretic effect in humans

Answer 64

True. True. False. It does reduce MAC but only the highly selective drugs such as dexmedetomidine have lowered anaesthetic requirements to this degree. True. Rebound hypertension occurs on discontinuation of long term use. True. It inhibits the release of ADH.

Question 65

Ephedrine: Select true or false for each of the following statements. True False A. Is a catecholamine B. Causes the stimulation of both alpha and beta adrenoceptors C. Acts directly and indirectly on adrenoceptors D. Is a uterine relaxant E. Can exist in four isomeric forms, two of which are pharmacologically active.

Answer 65

False. It does not have a hydroxyl substitution of the benzene ring, and therefore cannot properly be called a catecholamine. True. True. It's main effects are from the release of noradrenaline but it also has some direct effect on receptors. False. All anaesthetic vapours are uterine relaxants. False. It can exist in four isomeric forms but the only active one is the l-form. Ephedrine is supplied as the racaemic mixture or simply in the l-form.

Question 66

The following are indications for the use of ACE inhibitors: Select true or false for each of the following statements. True False A. Pre-eclampsia B. Essential hypertension C. Hypertension secondary to bilateral renal artery stenosis D. Following acute myocardial infarction E. Chronic congestive cardiac failure

Answer 66

False. ACE Inhibitors are contraindicated in pregnancy. True. False. ACE Inhibitors are contraindicated in bilateral renal artery stenosis or unilateral renal artery stenosis supplying a single kidney as renal failure may supervene. True. True.

Question 67

Regarding digoxin: Select true or false for each of the following statements. True False A. 25% of the oral dose is absorbed B. 95% is bound to plasma proteins C. It is largely excreted unchanged in the urine D. Hyporkalaemia may cause raised serum levels of digoxin E. Toxicity may result in Mobitz type II heart block

Answer 67

False. It is well absorbed orally. False. There is insignificant binding to plasma proteins. True. True. True. All forms of heart block have been recorded in digitalis toxicity.

Question 68

The following drugs cause prolongation of the Q-T interval: Select true or false for each of the following statements. True False A. Sotalol B. Quinidine C. Verapamil D. Flecainide E. Disopyramide

Answer 68

True. Sotalol, a beta blocker, posesses class III activity, and both quinidine and disopyramide have class 1A actions with mild class III activity prolonging the cardiac action potential and hence the Q-T interval. True. False. False. Flecainide, a class IC antiarrhythmic agent does not directly prolong the Q-T interval. True.

Question 69

The following drugs have potassium sparing diuretic effects: Select true or false for each of the following statements. True False A. Enalapril B. Frusemide C. Triamterene D. Spironolactone E. Flecainide

Answer 69

True. The angiotensin converting enzyme inhibitors have an anti-aldosterone effect They act as weak potassium sparing diuretics and concomittant use of such drugs should be undertaken with care. False. Frusemide use can result in hypokalaemia. True. True. False. It has no diuretic effect.

Question 70

Sodium nitroprusside: Select true or false for each of the following statements. True False A. Acts by stimulating the release of nitric oxide in vascular tissue B. Acts as an arteriolar and venous dilator C. Is associated with a baroreceptor mediated rise in heart rate D. Rapidy decomposes in the presence of light E. Is broken down by non-specific plasma esterases

Answer 70

True. True. True. Is associated with a reflex tachycardia. False. Its decomposition is surprisingly slow: 50% of its activity remains after 2 days exposure to light. False. Breakdown occurs in red blood cells with production of cyanomethaemoglobin.

Question 71

The following are recognised complications of amiodarone: Select true or false for each of the following statements. True False A. Peripheral neuropathy B. Prologation of the Q-T interval C. Hyperthyoidism D. Reversible restrictive lung defect E. Optic atrophy

Answer 71

True. True. True. Hypo or hyper-thyroidism may occur at higher doses. True. Pulmonary fibrosis, if treated early and the amiodarone stopped, may regress. False. Corneal microdeposits rather than optic atrophy occur in long term use.

Question 72

The following Beta-blockers are metabolised predominantly by the liver: Select true or false for each of the following statements. True False A. Labetolol B. Propranolol C. Atenolol D. Metoprolol E. Sotalol

Answer 72

True. True. False. Atenolol and sotalol are water soluble and therefore predominantly metabolised by the kidney. True. False.

Question 73

The following Beta-blockers are metabolised predominantly by the liver: Select true or false for each of the following statements. True False A. Labetolol B. Propranolol C. Atenolol D. Metoprolol E. Sotalol

Answer 73

False. It has more affinity for beta receptors: beta:alpha 3:1 following oral ingestion and 7:1 after IV administration. False. This can occur secondary to it's alpha action. True. It does have significant ISA. True. False. It is one of the drugs used in pre-eclampsia.

Question 74

Labetolol: Select true or false for each of the following statements. True False A. Acts on alpha and beta receptors with higher affinity for alpha-receptors B. May cause retrograde ejaculation by its beta-blocking action C. Has significant intrinsic sympathomimetic activity (ISA) D. Causes significant postural hypotension E. Is contraindicated in pregnancy

Answer 74

False. It has more affinity for beta receptors: beta:alpha 3:1 following oral ingestion and 7:1 after IV administration. False. This can occur secondary to it's alpha action. True. It does have significant ISA. True. False. It is one of the drugs used in pre-eclampsia.

Question 75

The following are natural precursors of adrenaline: Select true or false for each of the following statements. True False A. Aspartate B. Glycine C. Glutamine D. Dihydroxyphenylalanine E. Dobutamine

Answer 75

False. False. False. True. False. Dopamine is a precursor of adrenaline. Dobutamine is a synthetic compound. The synthetic pathway is as follows:Tyrosine-DOPA-Dopamine-Noradrenaline-Adrenaline.

Question 76

Dopexamine hydrochloride: Select true or false for each of the following statements. True False A. Has significant alpha-adrenoceptor activity at higher doses B. Acts mainly at beta-1 receptors to produce an increased cardiac output C. Acts mainly at alpha-1 receptors to produce an increased cardiac output D. Requires use of a loading dose E. Improves renal blood flow at the expense of splanchnic blood flow

Answer 76

False. Dopexamine is an analogue of dopamine. False. It acts mainly at beta-2 and DA-1/DA-2 receptors. It has no alpha activity. It also inhibits uptake-1. False. False. False. It is a weak positive inotrope but powerful splanchnic vasodilator reducing afterload.

Question 77

Hyoscine hydrobromide (Scopolamine): Select true or false for each of the following statements. True False A. Is a less potent anti-sialagogue than atropine B. Does not cross the blood-brain barrier C. Is largely excreted unchanged in the urine D. Is an effective anti-emetic which can be delivered transdermally E. May produce excitement and restlessness

Answer 77

False. It is a more potent anti-sialagogue than atropine. False. It has central and peripheral effects, which include sedative, anti-emetic and anti-sialogogue actions. False. Only 1% is excreted unchanged. True. True. Through paradoxical central stimulation.

Question 78

Isoprenaline: Select true or false for each of the following statements. True False A. Has alpha and beta adrenergic activity B. Increases peripheral vascular resistance C. Is a naturally occuring catecholamine D. May decrease mean arterial pressure E. It's effects are mediated via adenylate cyclase

Answer 78

False. It acts on beta-1 and beta-2 receptors only. False. It causes a fall in peripheral vascular resistance via it's beta-2 effets. False. Isoprenaline is a synthetic catecholamine. True. True.

Question 79

Hydralazine: Select true or false for each of the following statements. True False A. Dilates arterioles and veins equally B. It's first pass metabolism is dependent on the acetylator status of the patient C. Increases cerebral blood flow D. May cause a lupus-like syndrome E. Is contraindicated in pre-eclampsia

Answer 79

False. Hydralazine is predominantly an arteriolar dilator. True. True. True. After chronic usage. Peripheral neuropathies and blood dyscrasias have also been reported. False.

Question 80

Nitric oxide (NO): Select true or false for each of the following statements. True False A. Is synthesised exclusively by vascular endothelium B. Is synthesised from L-asparagine C. Is produced by the lung D. Binds to haemoglobin with an affinity equal to that of carbon monoxide (CO) E. Ultimately is metabolised to nitrate which is excreted by the kidneys

Answer 80

False. Nitric oxide is also produced by macrophages and thrombocytes. False. It is synthesised from L-arginine. True. False. The haemoglobin molecule has an affinity 1500 times higher to NO than to CO. Nitrosyl haemoglobin is produced, which in the presence of oxygen, is oxidised to methaemoglobin. True.

Question 81

The following drugs exhibit tachyphylaxis: Select true or false for each of the following statements. True False A. Glyceryl trinitrate B. Ephedrine C. Suxemethonium D. Trimetaphan E. Hydralazine

Answer 81

True. True. False. Repeated doses can result in a prolonged dual block. True. False.