Test 119  (Pharmacology)

1. Gentamicin: 

a. is poorly soluble in lipid and therefore needs to be 
   given parenterally

b. is excreted exclusively by the kidneys

c. inhibits presynaptic acetylcholine release

d. stabilizes the post-synaptic membrane at the 
    neuromuscular junction

e. inhibits cell wall synthesis of bacteria

Answera.T  b.T  c.T  d.T  e.F
Gentamicin potentiates the effects of neuromuscular blocking agents. In addition, prolonged use can give rise to symptoms similar to myasthenia gravis.
 

2. Edrophonium:

a. inhibits the action of cholinesterase in the 
    neuromuscular junction

b. inhibits plasma cholinesterase

c. has little effect if given orally

d. is used in the diagnosis of myasthenia gravis

e. causes bradycardia

Answera.T   b.F  c.T  d.T  e.T
Edrophonium is marketed as Tensilon. It is used in the diagnosis of myasthenia gravis. It is poorly
lipid soluble and therefore poorly absorbed by the gut. It does not inhibits plasma cholinesterase.

 
3. Compared with bupivacaine, lignocaine:

a. is more extensively protein bound

b. is more potent

c. has a lower molecular weight

d. is less lipid soluble

e. has a higher pKa

Answera.F   b.F  c.T  d.T  e.F
Lignocaine is 64% bound to protein whereas bupivacaine is 96% protein bound. The relative potency of lignocaine is 1 whereas that of bupivacaine is 4. The molecular weight of lignocaine is 234 and that of bupivacaine is 288. The pKa for lignocaine is 7.9 and that for bupivacaine is 8.1. The pKa influences degree of ionization and therefore speed of onset.
.

4. Mannitol:

a. is an alcohol

b. is poorly absorbed from the gut

c. is used in the treatment of cerebral oedema

d. is completely filtered at the renal glomeruli and not 
    reabsorbed from the renal tubule

e. increases urinary excretion of water, sodium and 
    chloride

Answera.T  b.T  c.T  d.T  e.T

5. Vancomycin:

a. inhibits bacteria DNA synthesis

b. is effective against Gram negative aerobic organisms

c. is well absorbed from the gut

d. gives rise to hypotension if given too rapidly

e. stimulates the release of histamine

Answera.F   b.F  c.F  d.T  e.T
Vancomycin inhibits bacterial cell wall synthesis. it is effective against Gram positive aerobic organisms. It is poorly absorbed from the gut and is therefore useful in the treatment of pseudomembraneous colitis.

 
 

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