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Flashcards in Pharmacokinetics + dynamics Deck (40)
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2. With regard to a drug:
a. LD50 is 50% of the dose necessary to kill experimental animals
b. Efficacy is the maximum response produced by a drug

B: “In pharmacology, efficacy refers to the maximum response achievable from a drug. It is often described by the parameter Emax.”


4. 2mL of 0.5% wv is equal to
a. 1mg
b. 10mg
c. 100mg
d. 20mg

b. 10mg – 0.1% = 1:1000 = 1mg/ml, so 0.5% = 5mg x 2 ml = 10mg


5. What is an example of a phase II biotransformation?
a. Oxidation
b. Reduction
c. Glycolysis
d. sulfation

The phase II rections are glucuronidation, acetylation, glutathione conjugation, glycine conjugation, sulfation, methylation, water conjugation


6. Regarding enzyme induction
a. It is irreversible
b. It takes 4 months to develop
c. Causes increase in smooth endoplasmic reticulum
d. Causes increase in rough endoplasmic reticulum



8. Regarding pharmacokinetics and pharmacodynamics
a. Diffusion is inversely proportionate to surface area and directly proportionate to thickness
b. The LD50 is 50% of the dose that kills most people
c. The LD50 is 50% of the dose at which toxicity occurs
d. Efficacy is the maximum response produced by a drug



10. Volume of distribution
a. Is inversely proportional to clearance
b. Is measured in mg/L
c. Is used to work out the maintenance dose
d. Is high in warfarin
e. Is proportional to half life



11. 5mL of 2% wv is equal to:
a. 10mg
b. 100mg
c. 200mg
d. 20mg
e. 40mg

b. 100mg 0.1% = 1:1000 = 1mg/mL, thus 2% = 20mg x 5mL = 100mg


12. Volume of distribution
a. Is calculated by dividing the amount of drug by its clearance
b. If high suggests homogeneous distribution through tissues
c. If low suggests homogeneous distribution through tissues
d. Of aspirin is greater than that of pethidine
e. Of midazolam is greater than that of warfarin



13. The volume of distribution
a. Is less than 70L for fluoxetine
b. Is calculated by dividing rate of elimination by concentrarion
c. Is inversely proportional to half life
d. Is about 5L/kg for pethidine
e. Is affected by the route of drug administration



14. By limiting liver blood flow, cardiac disease might inhibit the metabolism of all of the following EXCEPT:
a. Verapamil
b. Labetalol
c. Propoxyphene
d. Lignocaine
e. Trimethoprim

… other drugs with 100% bioavailability are: chlordiazepoxide, diazepam, lithium, phenobarbital, salicylic acid, sulfamethoxazole, valproic acid


15. The bioavailability of a drug
a. Must be 100% if given by inhalation
b. Is typically about 75% for IV administration
c. Is high if the drug is hydrophilic
d. Is equal to 1- the extraction ratio
e. Is 70% for orall administered digoxin



16. For a specific effect, drug A is more potent than drug B. It follows that:
a. Drug B is a partial agonist acting at the same receptor as drug A
b. Drug A causes a greater maximal effect than drug B
c. When present in identical concentrations, drug A causes a greater effect than drug B
d. Drug A has a lower ED50 than drug B
e. Drug B will have a steeper dose response curve than drug A

d- this is the definition of potency


17. The volume of distribution of a drug:
a. Relates its dose to its clearance
b. Is not an apparent volume
c. If high, implies greater concentration of drug in extravascular tissue
d. If high, implies greater plasma protein binding of the drug
e. If high, implies easier clearance of the drug by haemodialysis in overdose



18. Regarding receptors, the following statements are true EXCEPT:
a. Most are proteins
b. They largely determine quantitative relations between dose of a drug and pharmacologic effect
c. They are responsible for selectivity of a drug reaction
d. Mediate actions of pharmacologic antagonists
e. Spare receptors produce effect without the need for a drug

agonisism still required, just more sensitive


19. Regarding elimination kinetics, which statement is INCORRECT?
a. In first-order kinetics, the rate of elimination is directly proportional to drug concentration
b. Ethanol displays dose-dependent kinetics
c. In zero-order kinetics, the rate of elimination is constant
d. Most drugs display first-order kinetics
e. Phenytoin can display zero-order kinetics



20. For a drug that is present in a concentration 4 times its EC50
a. The time course of effect is linear, initially
b. The time course of effect will follow the exponential decline in concentration
c. Toxicity can be expected
d. All of the above may be true depending on the drug
e. Toxicity would not be expected



21. All of the following statements about spare receptors are correct EXCEPT:
a. Spare receptors are identical, in the absence of drug, to non spare receptors
b. Spare receptors do not bind drug when the maximal drug effect occurs
c. Spare receptors influence the sensitivity of the receptor system to the drug
d. Spare receptors activate the effector machinery of the cell without the need for a drug
e. Spare receptors may be detected by finding that the EC50 is less than the Kd for the agonist



22. Which of the following drug metabolising systems has been shown to differ in populations in genetically pre-determined ways?
a. Reductions
b. Acetylations of amines
c. Methylation
d. Glucuronidation
e. Sulfate conjugation

– isoniazid -> peripheral neuropathy, also oxidation (codeine -> reduced analgesia, EtOH -> toxicity, nortriptyline -> toxicity, s-warfarin -> bleeding), ester hydrolysis (succinylcholine -> prolonged apnea), o-demethylation (omeprazole -> increased efficacy)


23. Regarding receptor action
a. High concentrations of an agonist can never surmount a competitive antagonist
b. Partial agonists do not occupy all receptor sites
c. EC50 refers to the clinical effect at 50% of the maximal dose
d. Second messengers explain “spare receptors”
e. B-blockers and adrenaline exhibit physiological antagonism



24. Half-life
a. Is inversely proportional to Vd (volume of distribution)
b. Is the time required to attain 50% of steady-state concentration
c. Is directly proportional to clearance
d. Is decreased in renal failure
e. Is decreased in hepatic failure



25. Regarding bioavailability
a. Rectal administration has the same first-pass effect as oral
b. Transdermal is up to 90%
c. IV administration is between 95 and 100%
d. Is reduced in digoxin when given orally because of bacterial metabolism
e. Can be calculated by the extence of absorption (f) multiplied by the extraction ratio (ER)



26. Regarding biotransformation
a. Phase I reactions lead to increased polarity for excretion by the liver
b. Phase I reactions occur solely in the liver
c. Phase I reactions must undergo phase II reactions in order to be renally excreted
d. Hydroxylation and deamination are examples of phase I reactions
e. Rarely leads to toxic metabolites



27. The potency of a drug
a. Refers to the concentration needed to produce maximal effects
b. Depends on the efficiency of drug-receptor interaction
c. Is the limit of the dose-response relation
d. Determines clinical efficacy
e. Determines its toxic side-effects



28. The volume of distribution
a. Is proportionately related to the concentration of crug in the body
b. Is high for those drugs retained in the vascular compartment
c. Is a measure of the apparent space available in the body to contain a drug
d. For chloroquine is much smaller than that of digoxin
e. None of the above



29. Phase II reactions in metabolic biotransformation include all of the following EXCEPT:
a. Water conjugation
b. Cytochrome P-450 dependent oxidations
c. Acetylation
d. Methylation
e. Glucuronidation



30. An example of a drug receptor includes:
a. Leukotriene-B (LTB)
b. Tubulin
c. Arachinodic acid
d. Fibronectin
e. Tumour necrosis factor -1



31. The volume of distribution of a drug
a. Related the amount of a drug in the body to its plasma concentration
b. Is large for a drug extensively bound to plasma proteins
c. Is large for aspirin
d. Never exceeds 42 litres
e. Is not affected by albumin concentration



32. Receptor antagonists
a. Prevent agonists from binding to antagonists
b. Progressively inhibit agonist response to decreasing concentrations of antagonist
c. Cannot be negated at high doses of agonists
d. Bind to the receptor and activate it
e. Inhibit receptors to a degree proportionate to antagonist concentration



33. Regarding second messengers
a. cAMP has no role in calcium homeostasis
b. cAMP exerts most of its effects by stimulating cAMP-dependent protein kinases
c. inhibition of adenylyl cyclase results in increased cAMP
d. phospholipase C is situated in the cell nucleus
e. phospholipase C catalyses IP3 into PIP2 and DAG



34. The volume of distribution of a drug:
a. Relates the amount of a drug in the body to its plasma concentration
b. Is large for a drug extensively bound to plasma proteins
c. Is large for aspirin
d. Never exceeds 42 litres
e. Is not affected by albumin concentration