Oral administration route methadone

Methadone is rapidly absorbed after all routes of exposure. When administered orally, methadone is approximately one-half as potent as when given par-enterally. Oral administration results in a delay of the onset, a lowering of the peak, and an increase in the duration of analgesic effect. It is metabolized primarily in the liver where it undergoes N-demethylation. Protein binding is 85%. Urinary excretion of methadone and its metabolites is dose dependent and comprises the major route of excretion only in doses exceeding 55 mg day It is excreted by glomerular... 

OPIOIDS MEXILETINE 1. Absorption of oral mexiletine is 1 by co-administration with morphine or diamorphine 2. Methadone may t mexiletine levels 1. Uncertain but thought to be due to an opioid-induced delay in gastric emptying 2. Methadone inhibits CYP2D6-mediated metabolism of mexiletine 1. Watch for poor response to mexiletine consider starting at a higher or using the intravenous route 2. Monitor PR, BP and ECG closely watch for mexiletine toxicity... 

The outstanding properties of methadone are its analgesic activity, its efficacy by the oral route, its extended duration of action in suppressing withdrawal symptoms in physically dependent individuals, and its tendency to show persistent effects with repeated administration. Miotic and respiratory-depressant effects can be detected for more than 24 hours after a single dose, and on repeated administration, marked sedation is seen in some patients. Effects on cough, bowel motility, biliary tone, and the secretion of pituitary hormones are qualitatively similar to those of morphine. 

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