Morphine is a pain medication of the opiate family that is found naturally in a dark brown, resinous form, from the poppy plant (Papaver somniferum). It can be taken orally or injected. It acts directly on the central nervous system (CNS) to induce analgesia and alter perception and emotional response to pain. Physical and psychic dependence and tolerance may develop with repeated administration. It can be taken for both acute pain and chronic pain and is frequently used for pain from myocardial infarction, kidney stones, and during labor. Morphine can be administered by mouth, by injection into a muscle, by injection under the skin, intravenously, injection into the space around the spinal cord, or rectally. Its maximum effect is reached after about 20 minutes when administered intravenously and 60 minutes when administered by mouth, while the duration of its effect is 3–7 hours. Long-acting formulations of morphine are available as MS-Contin, Kadian, and other brand names as well as generically.

Protein binding: 30–40%
Metabolism: Hepatic 90%
Onset of action: 5 minutes (IV), 15 minutes (IM),[5] 20 minutes (PO)
Elimination half-life: 2–3 hours
Duration of action: 3–7 hours
Excretion: Renal 90%, biliary 10%
Formula: C17H19NO3
Molar mass: 285.343 g·mol−1
Solubility in water: HCl & sulf.: 60 mg/mL (20 °C)

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