Pharmacology 2003 Flashcards
(52 cards)
1
Q
Bioavailability of a drug may be influenced by:
- hepatic extraction
- gut wall metabolism
- apparent volume of distribution
- systemic clearance
- gastric acidity
A
TTFFT
2
Q
Nitric oxide
- is a gas at normal temperatures and pressures
- is responsible for the pharmacological effects of sodium nitroprusside
- is produced from L-arginine by NO synthase
- is derived from the epithelium of blood vessels
- has an elimination half life of ten minutes
A
TTTTF
3
Q
Haloperidol can cause:
- chest wall rigidity
- Parkinsonian tremor
- hyperpyrexia
- beta receptor blockade
- stimulation of chemoreceptor trigger zone
A
TTTFF
4
Q
Fentanyl:
- is 100x more potent than pethidine
- is less lipid soluble than morphine
- is a prodrug
- can cause skeletal muscle rigidity
- is readily absorbed from the renal tubules
A
FFFTT
-acts directly at the opioid receptor and is lipid soluble, therefore absorbed from the renal tubule
5
Q
Amethocaine:
- is hydrolyzed by plasma cholinesterase
- blocks calcium channels
- is metabolised to butylamino-benzoic acid
- can be administered as a 4% gel
- should not be combined with adrenaline
A
TFTTF
6
Q
Lidocaine:
- prolongs duration of cardiac action potential
- has a high hepatic extraction ratio
- has a lower systemic toxicity than the same dose of prilocaine
- can cause metHb-aemia
- acts by inhibiting the sodium/potassium pump mechanism
A
FTFFF
- blocks voltage gated fast sodium channels
- reduces duration and rate of rise of the cardiac action potential
7
Q
Metronidazole:
- is absorbed poorly after oral administration
- is affective against amoebiasis
- when taken with alcohol may cause abdo pain and flushing
- does not penetrate the BBB
- may cause red-brown urine
A
FTTFT
- completely absorbed after oral administration
- dark urine is a possible SE
- can penetrate BBB/breast milk/saliva
8
Q
Binding of drugs to plasma proteins:
- increases their pharmacological activity
- may depend on pH and temp
- allows rapid renal elimination of the drug
- retards penetration of the drug through the BBB
- is similar in the neonate and the adult
A
FTFTF
- only free drug is filtered at glomerulus
- protein bound drugs are not available to diffuse through membranes
- protein binding is reduced in the neonate
9
Q
Metoclopramide:
- is a selective D1 receptor antagonist
- has an action on gastric motility opposed by atropine
- increases prolactin release
- is a phenothiazine derivative
- lowers blood sugar
A
FTTFF
- metoclopramide acts at D2 and 5HT receptors
- it’s prokinetic effect is cholinergically mediated and therefore antagonised by atropine
- it does increase prolactin release
- it is a benzamine
10
Q
Substances in the ganglia of the autonomic NS include:
- ACh
- noradrenaline
- 5-hydroxytyptamine
- butyrylcholine
- dopamine
A
TFFFF
11
Q
Etomidate
- is an imidazole derivative
- is prepared in propylene glycol
- is metabolised by esterases
- has a positive inotropic effect
- produces excitatory effects that are diminished by opioid premedication
A
TTTFT
12
Q
The following drugs cause mydriasis when instilled into the conjunctival sac:
- cocaine
- ecothiopate
- amethocaine
- pilocarpine
- homatropine
A
TFFFT
- cocaine and homatropine cause pupillary dilatation
- cocaine interferes with adrenergic uptake of noradrenaline whilst homatropine is an antimuscarinic
- ecothiopate, amethocaine and pilocarpine produce pupil constriction
13
Q
Urinary pH influences reabsorption of drugs from the renal tubule by altering
- urine volume
- form of the phosphate buffer
- ionisation of weak bases and acids
- tubule cell metabolism
- active transport in tubules
A
FFTFF
14
Q
Drugs with a high hepatic extraction ratio include:
- morphine
- buprenorphine
- lignocaine
- aspirin
- warfarin
A
TTTFF
15
Q
Midazolam:
- becomes highly lipophilic at physiological pH
- prepared in solution at pH 3-4
- is hydroxylated in the liver
- is mainly excreted unchanged by the kidneys
- antagonises the CNS effects of gamma amino butyric acid
A
TTTFF
16
Q
The following penicillin compounds are penicillinase resistant
- phenethicillin
- flucloxacillin
- ampicillin
- cloxacillin
- benzyl penicillin
A
FTFTF
17
Q
When using local anaesthetic drugs the max recommended dose for a 70kg patient is:
- 3mg/kg bupivacaine
- 20ml of a 1% lidocaine solution
- 200mg of lidocaine + 1:200000 adrenaline
- 4ml of a 5% solution of cocaine
- 200mg of prilocaine
A
FTFFF
- prilocaine is 6mg/kg without adrenaline or 9mg/kg with
18
Q
The minimum alveolar concentration of a volatile agent is altered by:
- pregnancy
- duration of anaesthesia
- hyoscine
- hypothermia
- alpha2-adrenoceptor agonists
A
TFTTT
- mac is reduced by 40% in pregnancy
- mac is reduced by clonidine (alpha 2 agonist)
- mac is increased by alpha 1 agonists and being pyrexial
19
Q
The following enzymes help break down noradrenaline:
- catechol-O-methyl transferase
- dopamine a-oxidase
- MAO
- creatine phosphokinase
- aspartate transferase
A
TFTFF
20
Q
Fentanyl:
- is 100 times as potent as pethidine
- is less lipid soluble than morphine
- produces a biphasic respiratory response
- causes skeletal muscle rigidity
- is readily absorbed from renal tubules
A
FFTTT
- it is 1000 times as potent as pethidine
- may cause delayed resp depression
21
Q
Drugs with undergo zero order kinetics in normal conditions:
- phenytoin
- propranolol
- tubocurarine
- ethyl alcohol
- morphine
A
TFFTF
22
Q
The structure of the following drugs can be reversibly modified by changes in pH:
- lignocaine
- midazolam
- atracurium
- vecuronium
- diazepam
A
TTFTF
- local anaesthetics are weak bases so structure is pH dependent
- midazolam exhibits pH dependent water solubility but diazepam does not
- vecuronium has a monoquaternary structure hence its ionisation is pH dependent
23
Q
The following drugs cause mydriasis:
- morphine
- cocaine
- amitriptyline
- timolol
- phenylephrine
A
FTTFT
- phenylephrine, cocaine and amitriptylline are sympathomimetics
- timolol is a beta blocker used in glaucoma
24
Q
Aspirin:
- is broken down by esterases
- OD can cause metHb
- induces hepatic microsomal enzymes
- is preferentially eliminated in alkaline urine
- is CI in children under 12yrs
A
TFFTT
25
The following inhibit the neuronal reuptake of noradrenaline:
* ephedrine
* promethazine
* imipramine
* aminophylline
* cocaine
FFTFT
* imipramine and cocaine inhibit reuptake
* ephedrine enhances NA release
* promethazine and aminophylline have no effect
26
The following are true of opioid metabolism:
* morphine 3 glucuronide is an analgesic
* morphine 6 glucuronide is a ventilatory depressant
* alfentanil has pharmacologically active metabolites
* diamorphine has distribution half life of less than 5 mins
* norpethidine is excitatory to the CNS
FTFTT
27
Imipramine
* is a benzodiazepine derivative
* may interact with adrenaline
* may produce urinary retention
* is CI in glaucoma
* inhibits neuronal monoamine uptake
FTTTT
* it is a tricyclic antidepressant inhibiting reuptake of monoamine (mainly NA)
* it antagonises muscarinic cholinergic receptors and alpha 1 adrenergic receptors
28
Important mechanisms in the termination of action of catecholamines include:
* oxidative deamination by monoamine oxidase
* catecholamine uptake by adrenergic nerve endings
* uptake in smooth muscle
* metabolism by catechol-o-methyltransferase
* cleavage by esterases
TFFTF
29
Bupivacaine
* produces depolarization of the nerve membrane
* has a greater clearance than lidocaine
* has a higher pK than lidocaine
* is a racemic mix
* has a lipid solubility similar to lidocaine
FFTTF
30
Haloperidol can cause:
* chest wall rigidity
* Parkinsonian termor
* hyperpyrexia
* alpha receptor blockade
* chemoreceptor trigger zone stimulation
TTTFF
31
CNS toxicity of amide local anaesthetics
* is related to site of injection
* is unaffected by changes in hepatic blood flow
* correlates poorly with body weight in adults
* is decreased by premed with diazepam
* is additive when 2 drugs are used together
TFTTT
32
Resistance to non depolarizing muscle relaxants may be produced by:
* thermal injury
* phenytoin
* hypoproteinaemia
* hypocalcaemia
* carbamazepine
TTFFT
* hypermetabolic rate of the burn injury can result in an increased renal and hepatic clearance of non depolarising muscle relaxants
* after a burn there is increased ACh receptor population therefore increasing resistance to NDMR
* anticonvulsants such as carbamazepine and phenytoin increase resistance to NDMR
* hypoproteinaemia potentiates the action of NDMRs as does hypocalcaemia
33
Mivacurium
* blocks autonomic ganglia
* is antagonised by magnesium
* is a bisquaternary benzyisoquinolone
* has active breakdown products
* penetrates the BBB
FFTFF
- no discernable action on muscarinic receptors
- magnesium potentiates NDMRs
- does not cross BBB
34
Dilatation of the pupil:
* improves drainage of aqueous humour
* occurs to accommodation to near vision
* will occur if ACh-erase is inhibited
* occurs when circulating adrenaline concentrations increase
* is caused by paralysis of smooth muscle supplied by the sympathetic nerves to the eye
FFFTF
* drainage is improved by constriction of pupil
* anticholinesterase applied to the eye will cause miosis
* accommodation results in constriction of the pupil
* adrenaline causes dilator pupillae to contract resulting in myadriasis
35
The MAC of an inhaled agent:
* is decreased by clonidine
* may be expressed as volume %
* is increased in pyrexia
* is lower in males than females
* can be predicted by oil/water solubility
TTTFF
* potency is related to oil/gas partition coefficient
36
Isoflurane:
* has an oil/gas partition coefficient of around 91 at 37C
* is partially metabolised to trifluoroacetic acid
* has a MAC value of 1.15% in oxygen
* is a racemic mixture
* has a blood/gas partition coefficient of 2.3
TTTTF
37
Bupivacaine:
* has a chiral centre
* is less potent than procaine
* is an enzyme inhibitor
* is hydrolyzed in the plasma
* is stable in solution
TFTFT
* potency of a local anaesthetic is directly related to it's lipid solubility, bupivacaine is more lipid soluble than procaine
* amides are metabolised in the liver
* most amides contain a chiral centre
38
Therapy with IV mannitol may cause:
* hyponatraemia
* low osmolality of plasma
* an increased blood volume
* hyperkalaemia
* delayed increase in ICP
TFTFT
39
Propofol
* is formulated in propylene glycol
* is highly protein bound in blood
* has antiemetic properties
* is conjugated in the liver to glucuronides and sulphates
* has a low hepatic clearance
FTTTF
- has a high hepatic clearance
40
The blood/gas partition coefficient of an inhalational agent:
* correlates with anaesthetic potency
* increases with decreasing temperature
* is proportional to SVP
* indicates rapidity of induction of anaesthesia
* is altered by changes in FiO2
FTFTF
41
Opioid drugs:
* activate receptors found on ligand-gated ion channels
* can produce analgesia by a peripheral mechanism
* produce most of their useful effects by actions at the mu receptors
* mimic the endogenous peptide substance P
* are as effective intrathecally as they are systemically
FTTFF
* opioid receptors are G-proteins
* opioid receptors are manufactured by neurones in the dorsal root ganglion and can be exported peripherally
* do not mimic substance P but can increase it's concentration at synapses
* much more potent intrathecally (10-100 times)
42
Pethidine:
* has membrane stabilising properties
* has no active metabolites
* is a phenylpiperidine
* has anticholinergic properties
* is an opiate
TFTTF
* it's a phenylpiperidine opioid (drug which exerts its effects by combining with opioid receptors)
* norpethidine is an active metabolite which has convulsant effects
* pethidine is semisynthetic with structural similarity to atropine and anticholinergic properties
* it also has a local anaesthetic/membrane stabilising action
43
Methyldopa
* prevents release of ACh from nerve endings
* inhibits catechol- O- methyl transferase
* causes formation of a false transmitter
* blocks ganglionic transmission
* causes sleepiness
FFTFT
* methyldopa is an analogue of L-DOPA acting as a false substrate for dopa-decarboxylase, therefore resulting in false transmitter formation
* it does not affect release of ACh from nerve endings
* it does not inhibit COMT or block ganglionic transmission
* does cause sleepiness
44
The following inhibit the neuronal re-uptake of NA:
* ephedrine
* promethazine
* imipramine
* aminophylline
* cocaine
FFTFT
45
Suxamethonium does not pass significantly across the feto-placental membrane because:
* of it's elongated molecular configuration
* the placenta is rich in cholinesterase
* it is bound to plasma proteins
* suxamethonium has a low lipid solubility
* the blood concentration is never sufficiently high
FFFTF
46
Desflurane:
* has a lower boiling point than enflurane
* undergoes extensive hepatic metabolism
* has a similar SVP to halothane
* has a lower BG partition coefficient than halothane
* is an isomer of enflurane
TFFTF
* BP of des = 22.8C, BP of halothane = 56.5C
* BG coefficient is 0.42 compared to 2.4 for halothane
* desflurane and enflurane are ethers, enflurane has a Cl- atom which desflurane doesn't have
47
Agents which produce anaesthesia at a partial pressure in the brain of less than 10mmHg (1.3kPa) include:
* enflurane
* isoflurane
* desflurane
* halothane
* sevoflurane
FTFTF
48
Nitrous oxide:
* oxidises vit B12
* maintaines combustion
* has a critical temp of 32.5C
* inhibits methionine synthetase activity
* is less soluble in blood compared to nitrogen
TTFTF
* critical temp is 36.5C
* 40x more soluble in blood than nitrogen
49
Cocaine:
* is a vasoconstrictor
* causes hypothermia in OD
* is absorbed much more rapidly when mixed with adrenaline
* is broken down by cholinesterase
* releases ACh from adrenergic neurones
TFFFF
* blocks neuronal uptake of NA and inhibits MAO
* adrenergic effects are enhanced and vasoconstriction results
* body temp may increase owing to increased motor activity coupled with reduced heat loss
* should not be mixed with adrenaline as it's a vasoconstrictor, but would slow its absorption
* cocaine is metabolised by **hepatic carboxylesterase**
50
Alfentanil:
* is about 90% unionized at pH 7.4
* has faster elimination from the body than fentanyl
* has a smaller Vd than fentanyl
* is more potent than fentanyl
* is more protein bound than morphine
TTTFT
* elimination 1/2 life is 1-2h, fentanyl is 2-4hrs
* volume of distribution at steady state is 0.4-1 L/kg, fentanyl is 3-5 L/kg
* 92% protein bound, morphine is 20-40%
51
The following drugs are competitive antagonists at 5HT3 receptors:
* cimetidine
* metoclopramide
* omeprazole
* ketanserin
* granisetron
FTFFT
* metoclopramide acts mainly at dopamine but does act at 5HT3 at higher doses
52
Captopril
* enhances hypotensive effects of isoflurane
* is an angiotensin II receptor blocker
* causes an increase in plasma renin concentration
* antagonises chronotropic effects of isoprenaline
* inhibits breakdown of bradykinin
TFTFT
* increased incidence of hypotension with most agents due to reduced blood volume
* drugs like losartan act as angiotensin receptor blockers but captopril does not have this effect
* increased renin due to loss of negative feedback from angiotensin II
* does not interfere with sympathetic nervous system activity
* reduced metabolism of bradykinin (may be cause of rare SE of angioedema)
