Intramuscular drug administration morphine

Drug administration route The effects of intravenous morphine 10 mg given to 38 patients with moderate pain after surgery have been compared with those of intramuscular morphine 10 mg [113 ]. There was quicker analgesia with intravenous morphine, without serious respiratory depression. The level of sedation was greater after intravenous morphine, but this lasted for only 5 minutes. 

Opioids maybe administered in a variety of routes including oral (tablet and liquid), sublingual, rectal, transdermal, transmucosal, intravenous, subcutaneous, and intraspinal. While the oral and transdermal routes are most common, the method of administration is based on patient needs (severity of pain) and characteristics (swallowing difficulty and preference). Oral opioids have an onset of effect of 45 minutes, so intravenous or subcutaneous administration maybe preferred if more rapid relief is desired. Intramuscular injections are not recommended because of pain at the injection site and wide fluctuations in drug absorption and peak plasma concentrations achieved. More invasive routes of administration such as PCA and intraspinal (epidural and intrathecal) are primarily used postoperatively, but may also be used in refractory chronic pain situations. PCA delivers a self-administered dose via an infusion pump with a preprogrammed dose, minimum dosing interval, and maximum hourly dose. Morphine, fentanyl, and hydromorphone are commonly administered via PCA pumps by the intravenous route, but less frequently by the subcutaneous or epidural route. 

Pentazocine has been successfully used to relieve labour pain [201] and its obstetric use in place of pethidine is favoured by,its apparent inferior ability to pass the placental barrier [206]. A clinical trial of (+)- and (-)-pentazocine adds to the rare number of examples in which optical enantiomorphs have been evaluated [207]. In post-operative patients, response to 60 mg of the dextro isomer was less than that to 5 mg of morphine, while 25—29 mg of (-)-pentazocine was as effective as 10 mg of morphine. Hence most of the activity of the race-mate resides in the laevo isomer, as anticipated from results in animals [208]. Several studies of the distribution, excretion and metabolism of pentazocine have been made. Peak levels of the tritium-labelled drug (and its c/s-3-chloroallyl analogue) were present in the C.N.S. of a cat within 40 minutes of intramuscular administration [209], the comparable figure for morphine being 2 hours [210]. 

Morphine is available for oral, rectal, and parenteral administration. Oral formulations include immediate and controlled release tablets, as well as oral solution regular strength and concentrate. Parenterally, it can be administered subcutaneously, intramuscularly, intravenously, or by continuous infusion. It is a drug of abuse and can be nasally insufflated. 

Cxymorphone is a potent p agonist (10 times greater than morphine) that is used to treat severe pain. It is used by intramuscular, subcutaneous, intravenous, and rectal routes of administration. The intramusoular dose of oxymorphone (1 mg) has a half-life of 3 to 4 hours. It is a Schedule II drug. Cxymorphone, because of its 14-hydroxy group, has low antitussive activity. 

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