Pharmacokinetics, Pharmacodynamics, Pharmacology of Autonomic nervous system drugs, Autocoids
61. The following drugs are excreted mainly unchanged:
a. F: undergoes hepatic metabolism to form 2- & 3-hydroxychlorpropamide.
b. T
c. F: hydroxylated to form an active metabolite, oxazepam.
d. F: undergoes extensive first-pass metabolism.
62. Cumulative toxicity is more likely to occur if a drug:
a. T
b. F
c. T
d. T
63. The plasma elimination t1/2 of a drug:
a. T: half-life = 0.693 x Vd/Cl
b. F
c. F
d. T
64. The fraction of the total receptors to which a drug is bound is a function of:
a. T
b. F
c. T
d. F
65. A competitive antagonist:
a. T
b. T
c. T
d. F: this only happens with non-competitive antagonists.
66. Drug-receptor interaction:
a. F: a non-competitive antagonist prevents the agonist from producing its maximal effect by irreversible binding of the antagonist at ANY site.
b. F: other factors determine its clinical usefulness are therapeutic index, frequency of dosing, incidence of adverse side effects and cost.
c. F
d. F: the affinity of a drug determines the degree of binding to receptor while its efficacy determines the maximal response attainable; therefore the rate of occupancy of the receptor by the agonist has no bearing on its response as this depends on its intrinsic ability to trigger off the response.
67. The following refer to the renal clearance of drugs:
a. F: they will be more readily reabsorbed.
b. F: strong acids of pKa < 3 are virtually completely ionized over the entire range of urine pH and undergo only little reabsorption.
c. F: theophylline is extensively metabolized by cytochrome P450.
d. T
68. With regards to binding of drugs to plasma proteins:
a. F: protein binding generally does NOT interfere with active secretion.
b. F: half-life is dependent on the apparent volume of distribution and total clearance.
c. F: reduces drug-albumin binding capacity and may therefore increase free-drug concentration, but total plasma concentration remains unchanged.
d. F
69. The following decrease intra-ocular pressure:
a. T: a choline ester.
b. F: antimuscarinic agent.
c. T: beta-blocker.
d. F: antimuscarinic agent.
70. The following drugs can cause mydriasis:
a. T
b. F
c. F: causes miosis.
d. T: acts on both alpha and beta adrenergic receptors.