Repeated USMLE Questions Step 1 Review- 134- Pharmacology

Q- A 25-year-old man is treated with chloramphenicol for typhoid fever. He later develops pallor, fatigue, and pancytopenia.

Which adverse effect best explains this presentation?

A- Dose-dependent reversible anemia

B- Folate deficiency

C- Irreversible aplastic anemia

D- Vitamin B12 deficiency

C- Irreversible aplastic anemia- Chloramphenicol can rarely cause dose-independent, irreversible aplastic anemia, distinct from its reversible anemia caused by mitochondrial protein synthesis inhibition.

 

Q- A 60-year-old woman with hypertension is prescribed hydralazine.

Which adverse effect is most characteristically associated with this drug?

A- Gingival hyperplasia

B- Lupus-like syndrome

C- Pulmonary fibrosis

D- Tendon rupture

B- Lupus-like syndrome- Hydralazine, procainamide, and isoniazid are classically linked with drug-induced lupus.

 

Q- A 19-year-old college student with meningitis is treated with ceftriaxone.

What is the mechanism of action of this drug?

A- Disruption of bacterial cell membrane

B- Inhibition of peptidoglycan cross-linking

C- Inhibition of protein synthesis at the 50S ribosomal subunit

D- Inhibition of transpeptidase enzymes (penicillin-binding proteins)

D- Inhibition of transpeptidase enzymes (penicillin-binding proteins)- β-lactam antibiotics (penicillins, cephalosporins, carbapenems) bind PBPs, preventing cross-linking of peptidoglycan → bactericidal.

 

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