Morphine duration of action is generally:

Morphine duration of action is generally:

• A. 1-2 hours
• B. 4-5 hours
• C. 8-12 hours
• D. 24 hours

Answer: (B)

Morphine’s duration of action reflects how the drug distributes and how long its active metabolites continue to stimulate receptors. In adults, the meaningful analgesic effect from a typical dose lasts about four to five hours. After administration, morphine quickly enters the CNS and provides relief, but as it redistributes to less perfused tissues, the effect fades. Liver metabolism produces active metabolites, notably morphine-6-glucuronide, which can prolong analgesia, especially when renal clearance is reduced. Because of these pharmacokinetic and metabolic factors, durations much shorter (around 1–2 hours) or much longer (8–12 or 24 hours) are not typical for a standard single dose.

Morphine’s duration of action reflects how the drug distributes and how long its active metabolites continue to stimulate receptors. In adults, the meaningful analgesic effect from a typical dose lasts about four to five hours. After administration, morphine quickly enters the CNS and provides relief, but as it redistributes to less perfused tissues, the effect fades. Liver metabolism produces active metabolites, notably morphine-6-glucuronide, which can prolong analgesia, especially when renal clearance is reduced. Because of these pharmacokinetic and metabolic factors, durations much shorter (around 1–2 hours) or much longer (8–12 or 24 hours) are not typical for a standard single dose.