Pharmacology Answers-13

(A) Bleomycin is an antibiotic chemotherapeutic
agent that produces single- and doublestrand
breaks. It is useful in combination
therapy for Hodgkin disease because it produces
little myelosuppression, but it does produce serious
toxicity involving the lung, including lifethreatening
pulmonary fibrosis. Cisplatin (choice
B) is used alone and in combination to treat a
wide variety of carcinomas. Toxicity is expressed
as renal damage. Doxorubicin (choice C) is another natural product used in Hodgkin disease
that acts by DNA intercalation. The primary
toxicity of doxorubicin is cumulative
cardiac damage, so that lifetime dosage of the
drug must be limited. Mechlorethamine (choice
D) is a nitrogen mustard compound used in
Hodgkin disease that alkylates DNA, especially
at the N7 position of guanine. Its primary toxicity
is myelosuppression. Vincristine (choice E)
is a natural product derived from the vinca
plant and acts by interfering with microtubule
assembly. It is useful in HL. Its primary toxicity
is peripheral neuropathy, manifested as numbness,
tingling, and pain. A very similar vinca
alkaloid, vinblastine, has the same mechanism
of action, but causes myelosuppression rather
than neuropathies.

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