Pharmacokinetic drug-drug interactions can be desirable.

• A. False
• B. True
• C. Sometimes but not in practice.
• D. Not applicable.

Answer: (B)

Pharmacokinetic drug–drug interactions can be desirable when one medication intentionally alters the body's handling of another to improve therapeutic outcomes. A classic example is using a metabolic inhibitor to boost a partner drug’s exposure. Inhibitors such as ritonavir or cobicistat are co‑administered not for their own effect but to slow the metabolism of another drug, increasing its plasma concentration and lengthening its action. This boosting allows lower doses or less frequent dosing while maintaining efficacy. Another instance is using a renal excretion modifier like probenecid with penicillin to reduce clearance and extend penicillin’s half-life, enhancing and prolonging its antibacterial effect. These interactions are deliberately exploited to optimize therapy, but they require careful dosing and monitoring to avoid toxicity or subtherapeutic levels.