Pharmacology & Drug-Nutrient Interactions Flashcards

Which antibiotic class chelates divalent cations such as calcium, magnesium, and zinc, significantly reducing their absorption when taken together?

Answer: Tetracyclines

Tetracyclines form insoluble complexes with divalent and trivalent cations, impairing both antibiotic and mineral absorption.

Patients on warfarin (Coumadin) anticoagulation therapy require careful monitoring of their intake of which vitamin?

Answer: Vitamin K

Vitamin K is essential for the synthesis of clotting factors II, VII, IX, and X; fluctuating intake directly affects warfarin's anticoagulant effect.

Long-term use of proton pump inhibitors (PPIs) most commonly leads to clinically significant deficiency of which nutrient?

Answer: Vitamin B12

PPIs suppress gastric acid, which is required to cleave vitamin B12 from dietary protein and for intrinsic factor–mediated absorption.

Metformin, a first-line medication for type 2 diabetes, is associated with reduced absorption of which vitamin over time?

Answer: Vitamin B12

Metformin interferes with calcium-dependent absorption of the vitamin B12–intrinsic factor complex in the terminal ileum.

Which beverage most significantly interacts with statin medications by inhibiting CYP3A4 and increasing the risk of myopathy?

Answer: Grapefruit juice

Grapefruit juice contains furanocoumarins that irreversibly inhibit intestinal CYP3A4, dramatically increasing statin plasma levels and toxicity risk.

Patients prescribed monoamine oxidase inhibitors (MAOIs) must restrict dietary intake of which substance to prevent a potentially fatal hypertensive crisis?

Answer: Tyramine

MAOIs prevent the breakdown of tyramine in the gut and liver; tyramine accumulation triggers massive catecholamine release, causing severe hypertension.

Isoniazid (INH), used in the treatment of tuberculosis, acts as a structural antagonist to which B vitamin, frequently necessitating supplementation?

Answer: Pyridoxine (B6)

Isoniazid structurally resembles pyridoxine and competitively inhibits its conversion to the active coenzyme pyridoxal-5-phosphate, causing peripheral neuropathy.