Pharmacology Flashcards

A patient on warfarin is started on fluconazole. What is the expected effect on INR?

Answer: INR increases due to CYP2C9 inhibition

Fluconazole inhibits CYP2C9, which metabolizes warfarin, leading to elevated warfarin levels and increased INR.

Which beta-blocker is most cardioselective and preferred in a patient with reactive airway disease who requires beta-blockade?

Answer: Metoprolol succinate

Metoprolol succinate has the highest beta-1 selectivity among common beta-blockers, making it preferable in patients with reactive airway disease.

A patient taking lithium develops polyuria and polydipsia. Which medication can reduce lithium-induced nephrogenic diabetes insipidus?

Answer: Amiloride

Amiloride blocks ENaC channels in collecting ducts, reducing lithium entry into renal tubular cells and alleviating nephrogenic DI.

Which opioid analgesic is contraindicated in patients with renal failure due to accumulation of a toxic metabolite?

Answer: Meperidine

Meperidine's metabolite normeperidine accumulates in renal failure and can cause seizures and CNS excitation.

A patient on isoniazid develops peripheral neuropathy. What is the recommended treatment?

Answer: Pyridoxine (vitamin B6) supplementation

Isoniazid causes pyridoxine deficiency by inhibiting its activation, and supplementation with vitamin B6 prevents and treats peripheral neuropathy.

Which class of antibiotics inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins?

Answer: Beta-lactams

Beta-lactam antibiotics (penicillins, cephalosporins, carbapenems) bind to penicillin-binding proteins and inhibit transpeptidation of peptidoglycan.

A patient with gout is started on allopurinol. What is its mechanism of action?

Answer: Inhibits xanthine oxidase, reducing uric acid synthesis

Allopurinol inhibits xanthine oxidase, the enzyme that converts hypoxanthine and xanthine to uric acid, thereby reducing uric acid production.