In this article, we will discuss Morphine Sulfate (Dosage). So, let’s get started.
Morphine sulfate 0.1-0.2 mg/kg/dose SC, maximum dose 15 mg. It is given IV 2-5 mg/dose for preoperative medication, postoperative pain, restlessness, pulmonary edema. For continuous infusion in neonates 0,01-0,02 mg/kg/hr, infants and children 0.025-0.2 mg/kg/hr.
Mechanism of Action
Morphine, a full opioid agonist, is relatively selective for the mu receptor, although it can interact with other opioid receptors at higher doses. In addition to analgesia, the widely diverse effects of morphine sulfate include drowsiness, changes in mood, respiratory depression, decreased gastrointestinal motility, nausea, vomiting, and alterations of the endocrine and autonomic nervous system.
Effects on the Central Nervous System (CNS)
The principle therapeutic action of morphine is analgesia. Other therapeutic effects of morphine include anxiolysis, euphoria and feelings of relaxation. Although the precise mechanism of the analgesic action is unknown, specific CNS opiate receptors and endogenous compounds with morphine-like activity have been identified throughout the brain and spinal cord and are likely to play a role in the expression and perception of analgesic effects. In common with other opioids, morphine causes respiratory depression, in part by a direct effect on the brainstem respiratory centers. Morphine and related opioids depress the cough reflect by direct effect on the cough center in the medulla. Morphine causes miosis, even in total darkness.
Effects on the Gastrointestinal Tract and on Other Smooth Muscle
Gastric, biliary and pancreatic secretions are decreased by morphine. Morphine causes a reduction in motility and is associated with an increase in tone in the antrum of the stomach duodenum. Digestion of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive peristaltic waves in the colon are decreased, while tone is increased to the point of spasm. The end result may be constipation. Morphine can cause a marked increase in biliary tract pressure as a result of spasm of the sphincter of Oddi. Morphine may also cause spasm of the sphincter of the urinary bladder.
Effects of the Cardiovascular System
In therapeutic doses, morphine does not usually exert major effects on the cardiovascular system. Morphine produces peripheral vasodilation which may result in orthostatic hypotension and fainting. Release of histamine can occur, which may play a role in opioid-induced hypotension. Manifestations of histamine release and/or peripheral vasodilation may include pruritus, flushing, red eyes, and sweating.
Opioid agonists have been shown to have a variety of effects on the secretion of hormones. Opioids inhibit the secretion of ACTH, cortisol, and luteinizing hormones (LIL) in humans. They also stimulate prolactin, growth hormone (GH) secretion, and pancreatic secretion of insulin and glucagon in humans and other species, rats and dogs. Thyroid stimulating hormone (TSH) has been shown to be both inhibited and simulated by opioids.
Opioids have been shown to have a variety of effects on components of the immune system in in vitro and animal models. The clinical significance of these findings is unknown.
Adult dose: 10-30 mg IM or oral q 12 hr.
C/I: Respiratory depression, coma, seizures, bronchial asthma, head injury, raised intracranial pressure, and acute hepatic disease.
(Inj morphine sulfate ampoules 10 mg, 15 mg, 25 mg per ml; morcontin 10 mg, 30 mg, 60 mg, 100 mg CR tabs, duramor, rumorf, vermor tabs 10 mg and 30 mg, rilimorf 10 mg, 20 mg, 60 mg SR tab).