Morphine intraspinal

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. 

Dosages and routes of administration Morphine is available in different salt forms but the hydrochloride and sulfate (Vermeire and Remon, 1999) are used preferentially. The compound can be administered by the oral, parenteral or intraspinal route. Oral application is preferred for chronic pain treatment and various slow release forms have been developed to reduce the administration frequency to 2-3 times per day (Bourke et al., 2000). Parenteral morphine is used in intravenous or intramuscular doses of 10 mg, mostly for postoperative pain and self-administration devices are available for patient-controlled analgesia (PCA). Morphine is additionally used for intraspinal (epidural or intrathecal) administration. Morphine is absorbed reasonably well in the lower gastrointestinal tract and can be given as suppositories. 

Medico-technical instruments such as infusion pumps can be used in PCA (patient-controlled analgesia, Fig. 1) to provide patient-orientated and therapy as required, e.g. with morphine injection solutions. Depending on the patients perception of pain, they may add small doses of analgesics to the basic infusion by means of an electrically controlled infusion pump. The physician specifies the basic dose, which is infused independent of patient demands, the boluses that can be demanded, an hourly maximum dose and a refractory time that cannot be reduced between two doses. The infusion may be given intravenously, subcutaneously, epidurally or intraspinally. 

Complications have been described after the insertion of 157 intrathecal catheters in 142 patients (15). In most cases problems were related to the placement procedure, with subsequent neurological complications. Clinically unsuspected degeneration of the posterior columns, perhaps related to intraspinal infusion of morphine or to a paraneoplastic effect, has been observed postmortem in two patients with implanted pumps (16). 

Coombs DW, Fratkin JD, Meier FA, Nierenberg DW, Saunders RL. Neuropathologic lesions and CSF morphine concentrations during chronic continuous intraspinal morphine infusion. A clinical and post-mortem study. Pain 1985 22(4) 337-51. 

Skin Pruritus, a common adverse effect related to opioid use, affects psychosocial well-being. The hterature on the pathogenesis of opioid-induced pruritus is hmited, and treatment options for this condition remain largely unsatisfactory [48 ]. The associated susceptibility factors include epidural or intraspinal administration, higher doses of opioids, parturients, and intrathecal morphine administration. 

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