Methadone hydrochloride (Methadose)

Methadone hydrochloride (Methadose) is a synthetic opioid drug that is used to treat chronic pain and addiction to heroin and related drugs.

It works by stimulating the mu-opioid receptor on the surface of nerve cells in the brain and the spinal cord, which reduces the transmission of pain signals. By stimulating this receptor, it also mimics the action of drugs like heroin, but is cleared from the body more slowly. This allows addicts to stop taking heroin while avoiding withdrawal symptoms and the risk of infection from continued injection. However, methadone is usually given indefinitely, and can itself be very difficult to stop taking. Methadone maintenance therapy is usually coupled with psychological counselling to help resolve their addictive behaviour.

Methadone is normally taken by mouth as a solution. However, it can also be injected. The dose is usually adjusted on a patient-by-patient basis to relieve pain or to prevent withdrawal symptoms. For the relief of pain, the typical dose is 5 to 10mg three to four times a day, while for addiction it is started at a dose of 10 to 40mg once a day, being gradually increased to around 60 to 120mg once a day.

Although it is used as a maintenance therapy to keep addicts off heroin, methadone can itself be abused.

Side-effects of methadone can include nausea, diarrhoea and vomiting, as well as constipation and drowsiness. In higher doses, it can suppress breathing and lower blood pressure.

Since it is broken down by the CYP3A4 enzyme, methadone has important interactions with many anti-HIV drugs. These require the dose of methadone to be increased in most patients taking antiretroviral therapy, in order to prevent methadone levels from falling too low, resulting in withdrawal symptoms. Gradual dose increases in 10mg steps are recommended in patients experiencing withdrawal symptoms while taking a non-nucleoside reverse transcriptase inhibitor (NNRTI), including efavirenz (Sustiva) or nevirapine (Viramune).1 2 3 4 5 6 7 8 Although the effects on methadone levels are less dramatic with protease inhibitors, similar dose increases may be necessary in some patients, if withdrawal symptoms occur.9 10 However, the risk of withdrawal symptoms is low in patients taking indinavir (Crixivan).11 12

Despite these interactions, methadone use can improve adherence in HIV-positive patients, resulting in better outcomes of antiretroviral therapy in terms of viral load suppression and increases in CD4 cell counts.13 It may also reduce new HIV infections, not only by reducing injection behaviour, but also by reducing the number of sexual partners a person has and reducing the use of sex in exchange for drugs or money.14

References

  1. Clarke SM et al. The pharmacokinetics of methadone in HIV-positive patients receiving the non-nucleoside reverse transcriptase inhibitor efavirenz. Br J Clin Pharmacol 51: 213-217, 2001
  2. Boffito M et al. Undefined duration of opiate withdrawal induced by efavirenz in drug users with HIV infection and undergoing chronic methadone treatment. AIDS Res Hum Retroviruses 18: 341-342, 2002
  3. Bano Rodrigo MD et al. La nevirapina induce síntomas de abstinencia en pacientes en programa de mantenimiento con metadona con infección por VIH. Rev Clin Esp 200: 12-14, 2000
  4. Otero MJ et al. Nevirapine-induced withdrawal symptoms in HIV patients on methadone maintenance programme: an alert. AIDS 13: 1004-1005, 1999
  5. Altice FL et al. Nevirapine induced opiate withdrawal: among injection drug users with HIV infection receiving methadone. AIDS 13: 957-962, 1999
  6. Stocker H et al. Nevirapine significantly reduces the levels of racemic methadone and (R)-methadone in human immunodeficiency virus-infected patients. Antimicrob Agents Chemother 38: 4148-4153, 2004
  7. Clarke SM et al. Pharmacokinetic interactions of nevirapine and methadone and guidelines for use of nevirapine to treat injection drug users. Clin Infect Dis 33: 1595-1597, 2002
  8. Heelon MW et al. Methadone withdrawal when starting an antiretroviral regimen including nevirapine. Pharmacotherapy 19: 471-472, 1999
  9. McCance-Katz EF et al. The protease inhibitor lopinavir-ritonavir may produce opiate withdrawal in methadone-maintained patients. Clin Infect Dis 37: 476-482, 2003
  10. Gerber JG et al. Effect of ritonavir / saquinavir on stereoselective pharmacokinetics of methadone: results of AIDS Clinical Trials Group (ACTG) 401. J Acquir Immune Defic Syndr 27: 153-160, 2001
  11. Beauverie P et al. Therapeutic drug monitoring of methadone in HIV-infected patients receiving protease inhibitors. AIDS 12: 2510-2511, 1998
  12. Cantilena L et al. Lack of a pharmacokinetic interaction between indinavir and methadone. Clin Pharmacol Ther 65: 135, 1999
  13. Palepu A et al. Antiretroviral adherence and HIV treatment outcomes among HIV / HCV co-infected injection drug users: the role of methadone maintenance therapy. Drug Alcohol Depend 84: 188-194, 2006
  14. Gowing LR et al. Brief report: methadone treatment of injecting opioid users for prevention of HIV infection. J Gen Intern Med 21: 193-195, 2006

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This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.