Test 45   (Pharmacology)

1. The following are true about drug efficacy:

a. a drug A which is effective at 10 micrograms has more 
    efficacy than a drug B which is effective at 10 milligrams

b. it can be demonstrated in a double blind trial comparing the 
    drug with a placebo

c. it is a measure of the amount of drug needed to produce a 
   given effect

d. it is a measure of the drug bioavailability

e. it describes the ability of a drug to produce its therapeutic 
    effect

Answera.F   b.T   c.F   c.F   e.T
Drug A is more potent than than drug B and this does not describes the drug efficacy which is the ability of a drug to produce its therapeutic effect.

2. With regard to salicylate:

a. it is rapidly exreted by the kidney if the urine is rendered 
    acidic

b. it is a metabolite of aspirin

c. it causes hyperuricaemia at high doses

d. it potentiates the activity of warfarin

e. it has powerful antipyretic properties

Answera.F   b.T   c.F   d.T   e.T
It is excreted more readily if the urine is alkaline.
At high dose, it has uricosuric effect meaning increased uric acid excetion by the urine. However, at a lower dose it decreases the excretion of uric acid and therefore causes hyperuricaemia.

3. The following are true:

a. bioavailability describes the amount of drug which is 
    abosrbed following admistration

b. the volume of distribution is inversely proportional to the 
    clearance of a drug

c. clearance is calculated by dividing the dose adminatered by 
    the area under the time concnetration curve

d. for most drugs the amount eliminated from the plasma is 
    directly proportional to the amount present. 

e. in first order kinetics, the elimination half-life of a drug is 
    indidependent of the dose

Answera.F   b.F   c.T   d.T   e.T
Bioavailability is the percentage of drug released from a formulation that becomes available for biological effect.
The volume of distribution is directly proportional to clearance of a drug

4. Cyclosporin A:

a. can only be given orally as it is too toxic to be given 
    intravenously

b. it may be given prophylactically to reduce organ rejection 
    before transplantation

c. causes little bone marrow suppression

d. causes renal impairment

e. acts speficially on cytotoxic T lymphocytes

Answera.F   b.T   c.T   d.T   e.T
It can be given topically, orally or intravenously.
It blocks the actions of cytotoxic T lymphocytes.

5. The following antibiotics are bacteriostatic:

a. penicillins

b. erythromycin

c. isoniazid

d. chloramphenicol

e. cotrimoxazole

Answera.F   b.T   c.F   d.T   e.F