Sun, 03 May 2026 16:34:29 +0000

A pharmacologist is testing a new antibiotic with a half-life of 6 hours. If a patient is given a 400 mg dose, how much of the drug remains in the body after 15 hours?
In an era of growing interest in precision medicine and drug efficacy, questions about how medications behave in the human body are more common than ever. Understanding a drug’s half-life—the time it takes for the amount in the bloodstream to reduce by half—helps patients and caregivers grasp how timing and dosage impact treatment. This particular antibiotic, with a half-life of 6 hours, offers a clear example studied alongside other therapeutics in pharmacological research. For a drug with a 6-hour half-life, the body metabolizes roughly 75% of the medication within 18 hours—up to three half-lives in this case. After 12 hours has passed, only half remains; 15 hours means slightly less, but not far from expected decay. Computational models and clinical data suggest approximately 62 mg remains in the bloodstream after 15 hours, though individual variation and metabolism influence real-world outcomes. Why is this detail gaining attention in the US? Rising awareness of antibiotic resistance fueled by advances in pathogen research and healthcare challenges has sparked demand for transparent, science-backed guidance. Patients increasingly seek clear explanations about medication timelines to make informed decisions and stay proactive about care. Actually, the math behind half-life decay follows predictable patterns based on biological elimination rates. With a 6-hour half-life, the remaining drug concentration after 15 hours can be estimated using exponential decay:
Remaining amount = Initial dose × (1/2)^(time elapsed / half-life)
This means after 15 hours (2.5 half-lives):
400 mg × (1/2)^2.5 ≈ 400 mg × 0.177 ≈ 62.7 mg