Internal-Medicine

268 13: Clinical Pharmacology
10. (A) Folate deficiency can be secondary to small
bowel disease, alcoholism, inadequate intake,
disease states with high cell turnover (hemolytic
anemia), drugs (methotrexate), and pregnancy.
The concentration of folate in plasma changes
rapidly with changes in food intake, so the
diagnosis of anemia secondary to folate deficiency
is made more reliable by measuring red
blood cell folate. (Brunton, p. 1460)
11. (D) Vitamin B 12
absorption is best in the distal
ileum. Receptors for the intrinsic factor are
present in the distal ileum, but mass action
absorption also occurs with large doses.
However, the oral route is still felt to be unreliable
if hematologic or neurologic effects are
present. The Schilling test, with and without
intrinsic factor, can help diagnose the exact
cause of B 12
deficiency. (Brunton, pp. 1454–1455)
12. (A) Sympathomimetic effects such as pupillary
dilatation, piloerection, hyperthermia, and
tachycardia are common in an overdosage of
LSD. Other symptoms include dizziness, weakness,
drowsiness, nausea, and paresthesias. The
hallucinogenic effects can last for hours and
are mainly visual. (Brunton, pp. 624–625)
13. (D) GI symptoms are the major side effects of
tetracycline. Stomatitis, glossitis, and diarrhea
are seen and may be related to superinfections.
Hepatic toxicity has been reported but is rare
except in massive doses or during pregnancy.
Tetracyclines can cause discoloration of teeth in
children and in fetuses of mothers given the
drug during pregnancy. (Brunton, p. 1178)
14. (D) Thrombocytopenia usually occurs after
weeks or months of therapy. It is due to formation
of drug-platelet complexes that evoke a
circulating antibody. Thrombocytopenia and
bleeding can be severe but resolve rapidly on
discontinuing the drug. The antibody is longlasting,
and reintroduction of quinidine, even
in a small dose, can rapidly cause thrombocytopenia.
Other hypersensitivity reactions to
quinidine include hepatitis, bone marrow suppression,
and a lupus syndrome. The most
common side effects of quinidine are gastrointestinal
and include nausea, vomiting, and
diarrhea. (Brunton, pp. 928–929)
15. (C) Lithium is used primarily for bipolar affective
disorder, either to treat mania or prevent
recurrences of the bipolar disorder. It has also
been used in severe unipolar depression. Acute
intoxication can result in vomiting, diarrhea,
tremor, ataxia, coma, and convulsions. Leukocytosis
is also a side effect of lithium therapy.
Polyuria and polydipsia secondary to acquired
nephrogenic diabetes insipidus is a common
side effect. Both acute and chronic intoxication
can be lethal. The toxic and therapeutic levels
of lithium are very close, and patients on
lithium require close medical observation,
including measurement of serum lithium levels.
(Brunton, pp. 487–488)
16. (E) The benefit of nitroglycerin is probably due
to diminution in cardiac output and work of the
heart. Nitroglycerin generally dilates most veins
and arteries, and this result in both a decreased
preload and a decreased afterload for the heart.
This leads to decreased myocardial oxygen
requirements. Although coronary artery dilation
also occurs, it is probably not as important in
relieving anginal pain. (Brunton, pp. 827–828)
17. (C) Allopurinol effectively blocks uric acid
production by inhibiting xanthine oxidase.
Allopurinol is indicated in patients with a
history of uric acid calculi of the urinary tract.
In addition, it is often used in patients with
malignancy (e.g., leukemia, lymphoma), particularly
when chemotherapy or radiation therapy
is being used. (Brunton, pp. 708–709)
18. (E) Heparin must be given parenterally (usually
intravenously or subcutaneously) to be
active, and its activity is monitored by the partial
thromboplastin time (PTT), not the PT. It is
safer than oral anticoagulants in pregnancy and
does not deplete clotting factors as its mode
of action. Rather, it potentiates the effect of
antithrombin III on the clotting cascade. It can
be neutralized by administration of protamine.
Because protamine can cause a bleeding tendency
by its own actions, it is used only when
bleeding is severe, and in the lowest possible
dose. When low-molecular weight-heparin is
used, it has a more predictable pharmacokinetic
profile which allows for a weight-adjusted