Pharm II Exam I Ch 26 EOC Questions

Which of the following describes the major difference between a first- and second-generation antihistamine? (A)selectivity at H1 receptors (B)ability to cross the blood-brain barrier (C)effectiveness in treating allergies (D)potency at blocking H1 receptors (E)indications for use

The answer is B: ability to cross the blood-brain barrier. The major problem with treatment of allergies with the first-generation antihistamines is the adverse effects of sedation. Answer A, selectivity at H1 receptors, may be the case for select first-generation versus second-generation agents but is not the major difference between the classes. Answer C, effectiveness in treating allergies, is not correct because both can effectively treat the symptoms of allergies, but second-generation agents can do so without significant sedation. Answer D, potency at blocking H1 receptors, is another measure of antagonist affinity and is not correct for the same reasons that A is not correct. Answer E, indications for use, is not correct because both types of agents are used for allergies.

Latanoprost is an agonist at the PGF2 receptors and is effective for the treatment of (A)cornea abrasions (B)ocular hypertension and open-angle glaucoma (C)ocular albinism (D)closed-angle glaucoma (E)allergic conjunctivitis

The answer is B: ocular hypertension and open-angle glaucoma. Latanoprost, like bimatoprost and travoprost, is an agonist at the PGF2α receptors and is among the most prescribed classes of antiglaucoma agents. Answer A, cornea abrasions, might call for the use of an ocular antihistamine. Answer C, ocular albinism, might make sense considering the bizarre adverse effect of latanoprost in darkening the color of the iris but is not approved by the U.S. Food and Drug Administration as an indication for latanoprost. Answer D, closed-angle glaucoma, is usually treated by carbonic anhydrase inhibitors (e.g., acetazolamide) because the pressure rises very high inside the eye and needs to be dropped rapidly. Answer E, allergic conjunctivitis, is best treated by one of the ocular antihistamines.

Which of the following drugs is the same as PGI2 (prostacyclin) and is used for the treatment of pulmonary hypertension? (A)misoprostol (B)alprostadil (C)epoprostenol (D)treprostinil (E)travoprost

The answer is C: epoprostenol. Epoprostenol is the same substance as PGI2 (prostacyclin) and is used for the treatment of pulmonary hypertension. Answer A, misoprostol, is a synthetic PGE1 analogue that is available in an orally administered formulation for the prevention of NSAID-induced gastric ulcers and duodenal ulcers. Answer B, alprostadil, is a naturally occurring prostaglandin but is known as PGE1. Answer D, treprostinil, is also used for pulmonary hypertension but is a stable analogue of prostacyclin, not the same as prostacyclin itself. Answer E, travoprost, is a PGF2α analogue and an agonist at FP receptors. It is used for the treatment of open-angle glaucoma.

Of the major serotonin (5-HT) receptors identified and used as targets for therapeutic agents, which one is the only one considered a ligand-gated ion channel? (A)5-HT1B (B)5-HT1D (C)5-HT2 (D)5-HT3 (E)5-HT4

The answer is D: 5-HT3. This type of receptor for serotonin is famous as the only biogenic amine receptor that is ionotropic. The other answers, A through C and E, are all types of metabotropic receptors, also known as G protein-coupled receptors.

Which of the following antihistamines would be best used to treat mild nausea and vomiting caused by motion sickness? (A)cetirizine (B)fexofenadine (C)loratadine (D)diphenhydramine (E)meclizine

The answer is E: meclizine. Meclizine is a first-generation antihistamine with higher antiemetic activity than other agents and is also less sedating. Answers A through C are second-generation antihistamines and gain little access to the CNS and thus are nonsedating and ideal for treating allergies but would be little help for motion sickness. Answer D, diphenhydramine, has antiemetic effects but is more sedating than meclizine and thus is not the ideal treatment agent. Dimenhydrinate, which is a mixture of diphenhydramine and 8-chlorotheophylline, is used for motion sickness, however.