Internal-Medicine

272 13: Clinical Pharmacology
52. (D) Benzene is associated with bone marrow
depression. Benzene is present to some extent
in most gasolines, and poisoning may result
from ingestion or vapors. Acute benzene poisoning
can cause severe CNS symptoms such
as blurred vision, tremors, shallow and rapid
respiration, ventricular irregularities, paralysis,
and loss of consciousness. (Brunton, pp. 625–626)
53. (F) Ethylene glycol is widely used as antifreeze.
It causes CNS depression and renal toxicity
characterized by oxalate crystals in the tubules.
As in methanol poisoning, ethanol is used as a
competitive substance for alcohol dehydrogenase
to decrease the rate of formation of toxic
metabolites. (Brunton, pp. 599–600)
54. (K) Digitalis and verapamil decrease the refractoriness
of the accessory pathways in Wolff-
Parkinson-White syndrome (WPW) and the
ventricular rate can exceed 300/min. This can
be life-threatening and is treated with IV procainamide
or cardioversion. (Kasper, pp. 1350–1351)
55. (I) Numerous cardiac and noncardiac medications
can cause torsades de pointes. Although
it has been described with amiodarone, this is
quite rare. The arrhythmia can result in sudden
death. Unstable forms of this arrhythmia are
treated with cardioversion. (Kasper, p. 1353)
56. (B) MAT usually occurs in the setting of
advanced lung disease. Treatment involves
withdrawing theophylline and improving lung
function. There may be some role for treatment
with verapamil. (Kasper, p. 1350)
57. (E) Adenosine is the agent of first choice for the
termination of AV nodal or AV reentrant tachycardias
that are not terminated by vagal
maneuvers such as carotid sinus massage. IV
beta-blockers and calcium channel blockers are
second choice. Digitalis IV acts too slowly and
is not recommended for this type of arrhythmia.
(Kasper, pp. 1347–1349)
58. (C, G, L) Melphalan is an alkylating agent of
the nitrogen mustard type. Although not curative
therapy, it is particularly useful in the
management of multiple myeloma, breast
cancer, and ovarian cancer. (Brunton, p. 1328)
59. (B, G, J) Methotrexate is classified as an
antimetabolite, and is a folic acid analogue.
Other tumors where methotrexate has an effect
include osteogenic sarcoma, mycosis fungoides,
and lung cancer. (Brunton, pp. 1338–1339)
60. (A) Bleomycin, a naturally occurring antibiotic,
is useful in Hodgkin’s disease, non-Hodgkin’s
lymphoma, and cancers of the testes, head and
neck, skin, esophagus, lungs, and genitourinary
tract. (Brunton, pp. 1361–1362)
61. (K) Flutamide is an antiandrogen that is useful
in prostate cancer. Leuprolide, a gonadotropinreleasing
hormone analogue, and various estrogen
compounds are the other hormonal-type
agents used in prostate cancer therapy. (Brunton,
p. 1388)
62. (C, G) Sensory loss is not a side effect of phenothiazines.
Parkinson-like symptoms disappear
when phenothiazine is withdrawn. Dystonic
movements involve the mouth, tongue, and
shoulder girdle. As well as having useful
antipsychotic effects, phenothiazines are useful
as antiemetics and antinausea agents. They can
also potentiate the effects of sedatives, analgesics,
and general anesthetics. Some phenothiazines
are intrinsically sedating, but none
of them commonly interfere with sleep. (Brunton,
pp. 477–480)
63. (B, F) The increased refractory period accounts
for the effect on tachycardia. Similar effects are
seen with procainamide. The slowed repolarization
can result in a prolonged QT interval.
Life-threatening polymorphic ventricular tachycardias
(torsades de pointes) can be provoked
by quinidine. It is rarely used in modern practice.
(Brunton, pp. 928–929)
64. (A, D) In susceptible individuals, the beta2-
adrenergic blocking effect of propranolol can
cause life-threatening bronchoconstriction.
Ephedrine, isoproterenol, and albuterol are betaadrenergic
agonists and cause bronchodilatation.