Methadone is a synthetic opioid narcotic drug used primarily to treat withdrawal from other opioids, such as heroin and oxycontin, reports the Office of National Drug Control Policy. A potent painkiller, methadone is considered safe to use over the long-term by the ONDCP. However, research reveals that the drug can still produce a variety of effects on both the brain and body when used over long periods of time.
Elimination of Cravings for Other Opiate Drugs
The primary, desired long-term effect for which methadone is indicated is the elimination of cravings for other opiate drugs. According to the University of Maryland Center for Substance Abuse Research, achieving this key effect involves careful monitoring of dosage by medical professionals who dispense the drug. When a person is beginning long-term treatment with methadone, his dose is titrated, or raised incrementally, to a level at which it will stabilize over time. This titration allows the individual receiving treatment to gradually become tolerant to the drug, reducing the occurrence of common physiological and psychological effects such as sedation, nausea, constipation, and altered cognitive function.
Changes in Health and Lifestyle
After taking methadone for periods of one year or longer, reports the National Highway Traffic Safety Administration, most recovering opiate addicts do not report adverse effects. However, lung and breathing problems can still arise after long-term use of methadone, reports the University of Maryland. Methadone, like other opioids, reduces the production of testosterone in both men and women, and can interfere with menstrual cycles in women when used for long periods of time. Additionally, long-term use of methadone can also cause reduced libido and sexual dysfunction in men and women, states the National Cancer Institute. These sorts of effects vary with each individual and dosage amount, yet they have the potential to alter a person's lifestyle and health, and should be weighed against the therapeutic effect of taking methadone for long periods of time.
Taking methadone over the long-term also can cause certain side effects from interactions with other chemicals. Even after someone has been taking methadone for over a year, drinking alcohol can greatly enhance the depressant effects of methadone, leading to problems such as respiratory depression and heavy sedation. Central nervous system depressant medications, including barbiturates as well as benzodiazepines such as diazepam, clonazepam, lorazepam and alprazolam, have the potential to amplify the sedating effects of methadone, even after tolerance to methadone has been long established. Another interaction of note is that between methadone and prescription opioid drugs. Since methadone is designed to occupy the brain's opioid receptors and effectively block the effects of other drugs of this class, prescription painkillers, such as codeine and hydrocodone, will not be effective in treating pain that arises through the analgesia that methadone produces.
Dependence and Withdrawal
The Office of Drug Control Policy acknowledges that long-term use of methadone is still long-term use of a potent opioid, and although methadone can improve a former addict's quality of life, it is highly addictive. Dependence is a major effect of long-term methadone use, and its unpleasant counterpart--withdrawal. After long periods of methadone use, a person who suddenly stops taking methadone will begin experiencing withdrawal effects usually 48 hours after the last dose. These effects include sweating, cramps, muscle aches, nausea, chills, runny nose and intense cravings for more methadone. While the effects of withdrawing from long-term use of methadone are not as severe as those of opioids such as heroin and morphine, reports the NHTSA, they persist for longer periods of time. When getting off methadone after prolonged use, a slow and gradual downward dose titration is advisable to prevent these unpleasant withdrawal effects.