Methadone (Dolophine) has an analgesic profile and potency similar to that of morphine but a longer duration of action and better oral bioavailability. The kinetic properties of methadone and its derivative, LAAM, have been shown to be useful in the treatment of opioid addiction, as discussed in Chapter 35.

Methadone is a useful analgesic drug for the treatment of moderate to severe pain. Unlike morphine, it is generally not used epidurally because of its long duration of action. It is also rarely or never used in PCA systems or in pregnant women during labor. The side effects and signs of overdose following methadone administration are similar to those observed with morphine. Overdose is treated with naloxone. Clearance of methadone is via the urine and bile as the cyclic N-demethylated drug. The ability to N-demethylate the drug decreases in elderly patients, prolonging the action of methadone. In such patients, dosing intervals should be longer than in younger patients. In addition, the pH of the urine has a major effect on clearance of the drug. Alkalinization of the urine or renal insufficiency decreases excretion of the drug.

Drug interactions and precautions for the use of methadone are similar to those of morphine. In addition, rifampicin and hydantoins markedly increase the metabolism of methadone and can precipitate withdrawal from methadone. Conversely, the tricyclic anti-depressants and certain benzodiazepines can inhibit metabolism of methadone, thereby increasing accumulation of the drug, prolonging its half-life, and intensifying its side effects. Continuous dosing with methadone may lead to drug accumulation and to an increased incidence of side effects; methadone is generally not used for PCA. In pregnant heroin-addicted women, substitution of methadone for heroin has been shown to be associated with fewer low-birth-weight newborns and fewer learning and cognition problems later in the life of the child.

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How To Win Your War Against Anxiety Disorders

How To Win Your War Against Anxiety Disorders

Tips And Tricks For Relieving Anxiety... Fast Everyone feels anxious sometimes. Whether work is getting to us or we're simply having hard time managing all that we have to do, we can feel overwhelmed and worried that we might not be able to manage it all. When these feelings hit, we don't have to suffer. By taking some simple steps, you can begin to create a calmer attitude, one that not only helps you feel better, but one that allows you the chance to make better decisions about what you need to do next.

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