QUESTION: 9

A patient with multibacillary leprosy is on dapsone, clofazimine, and rifampin. Which of the following is true regarding the mechanism of action of the medications listed?

Dapsone is bacteriostatic because of its inhibitory effects on dihydrofolate reductase
Dapsone is bacteriostatic because of its inhibitory effects on myeloperoxidase
Clofazimine is bactericidal by directly inhibiting bacterial DNA polymerase
Rifampin is bacteriostatic by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase
Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase

Answer(s): E

Explanation:

A, B – false – dapsone inhibits bacterial synthesis of dihydrofolic acid, via competition with para- aminobenzoate for the active site of dihydropteroate synthetase. Dapsone is both bacteriostatic and weakly bactericidal against M. leprae. Neither of the listed mechanisms are the cause of these effects. C – False – A substance with both anti-leprosy and anti-inflammatory activity, clofazimine is weakly bactericidal against M. leprae by binding to the guanine bases of bacterial DNA, not DNA polymerase directly. D – False – See below. E – True – Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase.

Reveal Solution Next Question

QUESTION: 10

You prescribe doxepin to a 37-year-old woman to treat neurotic excoriations on her arms. The patient is concerned about the side effects of this drug. Which of the following is not a side effect of doxepin:

Xerostomia
Liver toxicity
Somnolence
Urinary retention
Constipation

Answer(s): B

Explanation:

A,C,D,E – False – Doxepin is a tricyclic antidepressant with H1 and H2 antihistamine activity. Side effects include sedation and anticholinergic effects (dry mouth, urinary retention, and constipation). Although extensively metabolized by the liver and excreted by the kidney, liver toxicity is very rare. Nephrotoxicity, on the other hand, is a well-known serious adverse effect of long term doxepin use.

Reveal Solution Next Question

QUESTION: 11

Which of the following illnesses is an example of a type III hypersensitivity reaction?

Lupus
Graves disease
Hashiomoto’s thyroiditis
Allergic rhinitis
Myasthenia gravis

Answer(s): A

Explanation:

A type III hypersensitivity reaction is mediated by immune complex deposition. In lupus, auto- antibodies are formed and these complexes are deposited in other tissues, especially in the kidneys, skin, and joints. Graves disease and myasthenia gravis are examples of type II but in some classification systems they are called type V reactions. The auto-antibodies created in Graves attack TSH receptors in the thyroid, whereas in Myasthenia the target is the acetylcholine receptor. Hashimoto’s thyroiditis is usually considered an example of a combination of type II and IV reactions, as T cells are directed at thyroid antigens and antibodies are also produced. Allergic rhinitis is a classic example of a type I, IgE mediated reaction.

Reveal Solution Next Question

QUESTION: 12

Which of the following is a side effect of valproic acid?

Gingival hyperplasia
Pancreatitis
Kidney stones
Weight loss
Euphoria

Answer(s): B

Explanation:

Pancreatitis is one of the most serious adverse effects that can be caused by valproic acid. Gingival hyperplasia is a side effect of Phenytoin. Kidney stones and weight loss can be a side effect of zonisamide or topiramate.

Reveal Solution Next Question

Free NAPLEX Exam Braindumps (page: 3)

QUESTION: 9

Explanation:

QUESTION: 10

Explanation:

QUESTION: 11

Explanation:

QUESTION: 12

Explanation: