Peak plasma concentration timing for digoxin after oral administration is typically about how many hours?

• A. 1 hour
• B. 8-10 hours
• C. 30 minutes after IV
• D. 24 hours

Answer: (B)

Peak plasma concentration after an oral digoxin dose mainly reflects how slowly the drug is absorbed from the gut. Digoxin has relatively slow and variable oral absorption, and when given in standard oral form (especially slower-release preparations), the rate of absorption into the bloodstream is the limiting factor for reaching the maximum level. As a result, the peak concentration typically occurs several hours after dosing, commonly around 8–10 hours. This contrasts with intravenous administration, where the rise to peak is much faster because absorption is bypassed. The long elimination half-life of digoxin means it stays in the body for a long time, but that doesn’t change when the peak occurs after an oral dose—that peak is determined by how quickly the drug enters the circulation.