A 65-year-old man with hypertension (BP 158/92 mmHg, HR 78) begins once-daily oral antihypertensive therapy. He asks when the medication will stabilize at near-constant average plasma concentration with consistent dosing. Laboratory studies show normal renal function (creatinine 0.9 mg/dL). He denies previous antihypertensive use. Assuming first-order elimination kinetics and no loading dose, after how many half-lives will steady-state plasma concentration be approached?
- A)Immediately after the first dose because oral drugs bypass distribution
- B)After one half-life regardless of clearance
- C)After about 4 to 5 half-livesGABARITO
- D)After one dosing interval
- E)Only after receptor upregulation occurs
Explicação
With repeated dosing under first-order kinetics, steady state is approached after about 4 to 5 half-lives. At that point, the rate of drug administration equals the rate of elimination. This principle applies broadly regardless of the specific organ system bei... Ver explicação completa e trilha adaptativa →