Morphines

Morphines is the term used to refer to morphine and its related alkaloids and derivatives. Morphine is a naturally occurring opiate alkaloid found in the opium poppy, Papaver somniferum, and is the principal active constituent of opium. It was first isolated in 1804 by Friedrich Sertürner, who named it after Morpheus, the Greek god of dreams.

Chemically, morphine is a phenanthrene derivative. It exists as a free base and as various salt forms, such as morphine sulfate or morphine hydrochloride, which influence solubility and route of administration. It has poor oral bioavailability due to first-pass metabolism, but can be given orally, intravenously, intramuscularly, or via other routes. Semisynthetic derivatives include codeine, hydromorphone, and buprenorphine; heroin is diacetylmorphine, a more lipophilic prodrug.

Pharmacologically, morphine is a potent agonist at the mu-opioid receptor, producing analgesia and sedation, with additional effects on the kappa and delta receptors. After administration, it is metabolized in the liver to morphine-3-glucuronide and morphine-6-glucuronide, the latter of which may contribute to analgesia in some patients. Common adverse effects include nausea, vomiting, constipation, and respiratory depression; tolerance and physical dependence can develop with long-term use. Overdose is treated with antagonists such as naloxone.

Morphines are used medically for severe acute and chronic pain, particularly in cancer and palliative care, and in anesthesia as an adjunct. They are tightly regulated as controlled substances in most countries due to abuse potential.