An opioid is defined as “A drug that contains opium, opium derivatives or synthetic drugs that have an opium-like effect.” (Harris, 2010) Morphine is a prototype opioid that is used to treat patients with moderate to severe pain usually associated with postoperative pain or neoplastic disease. (Tiziani, 2010) Morphine produces pharmacological actions such as pain relief, by acting on receptors located on neural cell membranes. (News Medical, 2015) Morphine simulates the actions of endorphins and enkephalins at opioid receptors, (Bryant & Knights, 2011) The capabilities of morphine span further than just the treatment of pain, it can be used to supress an unproductive …show more content…
(Bryant & Knights, 2011) It is absorbed in the liver with first-pass effect making it quick acting but with a poor bioavailability. When taken orally the bioavailability is around 40%, therefore a 30mg dose of morphine is the equivalent of 10mg dose of morphine given parentally. (Bryant & Knights, 2011) Morphine has short half-life of 1.5 hours-7 hours, however this can depend on the patient as many contributing factors such as weight, sex and height, age and pre-existing co morbidities can all effect half-life. (Drugs and human performance factsheets, 2015) Morphine is distributed throughout the body in tissue and only a small percentage crosses the blood-brain barrier. Morphine’s active metabolite is morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G), Morphine is then glucuronidated by the phase 2 enzyme known as UDP-glucuronosyl transfease-2B7. Morphine may also be metabolised into smaller quantities of nor-morphine, codeine and hydro-morphine. (News Medical, 2015) Morphine is excreted primarily by the kidneys, and 7-10% enters the enterohepatic circulation, therefore increasing the half-life, as it is being reabsorbed by the liver and then cast-off into the intestine. (Harris, …show more content…
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