Constipation methadone

Methadone is not without side effects. Although it is less addictive than other opiates, methadone can be abused and requires monitored use. Common side effects include sedation and constipation. Methadone is also safer than other opiates in overdose but does require careful monitoring of respiratory status when an overdose occurs. 

Deaths, cardiac and resp have been reported during initiation and conversion of pain pts to methadone Tx from Tx w/ other opioids Uses Severe pain detox w/ maint of narcotic addiction Action Narcotic analgesic Dose Adults. 2.5-10 mg IM q3-8h or 5-15 mg PO q8h titrate as needed Feds. 0.7 mg/kg/24 h PO or IM -s- q8h T slowly to avoid resp depression X in renal impair Caution [B/D (prolonged use/high doses at term), + (w/ doses =/> 20 mg/24 h)], severe liver Dz Disp Tabs, inj SE Resp depression, sedation, constipation, urinary retention, T QT interval, arrhythmias Interactions T Effects W/ cimetidine, CNS depressants, protease inhibitors EtOH T effects OF anticoagulants, antihistamines, barbiturates, glutethimide, methocarbamol ... 

Methadone Slow-acting agonist of M-opioid receptor Acute effects similar to morphine (see text) Substitution therapy for opioid addicts High oral bioavailability half-life highly variable among individuals (range 4-130 h) Toxicity Respiratory depression, constipation, miosis, tolerance, dependence, and withdrawal symptoms... 

Chronic constipation is also another troublesome side effect of prolonged methadone use. As discussed previously, methadone significantly slows the involuntary movements of the small and large intestines. By consuming a high-fiber diet and plenty of water, chronic users of methadone can reduce, but not eliminate, the occurrence of constipation. 

Actions The analgesic activity of methadone is equivalent to that of morphine. Methadone exhibits strong analgesic action when administered orally, in contrast to morphine, which is only partially absorbed from the gastrointestinal tract. The miotic and respiratory depressant actions of methadone have average half-lives of 24 hours. Like morphine, methadone increases biliary pressure, and is also constipating. 

In the second study there were 174 patients in two similar experimental groups in whom injectable rather than inhaled heroin was used (5). A response to treatment was defined as at least a 40% improvement in physical, mental, or social domains of quality of life, if not accompanied by a substantial (over 20%) increase in the use of another illicit drug, such as cocaine or amphetamines. After 12 months those who took methadone and heroin (smoked or injected) had significantly better outcomes. The incidences of adverse effects (constipation and drowsiness) were similar in all the groups. However, owing to the limitations of the study and the complex nature of drug dependence, the therapeutic outcomes could not be justifiably and solely attributed to the specific drug(s). 

Methadone 16 mg/day was effective in 29 patients with restless legs syndrome that had not responded to dopamine receptor agonists (9). Most (n = 17) were still taking methadone at follow-up and reported a 75% reduction in symptoms. Of 27 patients, 17 reported at least one adverse event while taking methadone, including constipation (n = 11), fatigue (n = 2), and insomnia, sedation, rash, reduced libido, confusion, and hypertension (one each). Five patients stopped treatment because of adverse events. 

In a randomized, double-bhnd, placebo-controlled trial of the efficacy of intravenous methylnaltrexone (0.015-0.095 mg/kg) in treating chronic methadone-induced constipation in 22 patients attending a methadone maintenance program (oral methadone linctus 30-100 mg/day), methylnaltrexone induced immediate bowel movements in all subjects (32). There were no opioid withdrawal symptoms or significant adverse effects. 

Tolerance to the narcotic properties of methadone develops within 4—6 weeks, but tolerance to the autonomic effects (for example constipation and sweating) develops more slowly. 

Yuan CS, Foss JF, O Connor M, Osinski J, Karrison T, Moss J, Roizen MF. Methylnaltrexone for reversal of constipation due to chronic methadone use a randomized controlled trial. JAMA 2000 283(3) 367-72. 

In the last 32 there were significant improvements in pain intensity, nausea and vomiting, constipation, and drowsiness, with a 20% increase in methadone dose over and above the recommended starting dose. 

Methadone has Food and Drug Administration indications for the management of pain in adults and for adult narcotic addiction. Adverse events are those expected from opiate exposures gastrointestinal symptoms, CNS depression, and respiratory depression in larger doses, bradycardia, and constipation. Methadone appears to be fairly well tolerated by... 

The major pharmacological actions of methadone, mediated by fi- and 6-receptor interactions, are similar to those of other opioids and include analgesia, sedation, respiratory depression, miosis, antitussive effects, and constipation. Methadone is administered as a racemic mixture (R,S- [ ] -methadone), but the analgesic activity is due almost entirely to the R(-)-isomer. When administered intramuscularly, methadone and morphine have equivalent analgesic potency. In contrast to morphine, methadone retains about 50% of its intramuscular analgesic potency when taken orally. ... 

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