Because many medications for HIV and for the prevention of opportunistic infections are broken down by the same liver enzymes that metabolize (break down) methadone, these drugs may cause changes in the way you respond to your methadone dose.
Some drugs increase the effects of methadone; others decrease it. Methadone can have an effect on the strength of some anti-HIV drugs too. The effects that can happen when methadone and these other drugs mix together in your body are called "drug interactions."
It's important to tell both the physician who provides your HIV care and the doctor at your methadone clinic about all the medications you're taking so that your methadone dose can be adjusted to deal with these effects and make you as comfortable as possible. The PWA Health Group has a handout available, complete with references, for you to give to your physician(s) if he/she is interested in more information on these interactions. Call us at (212) 255-0520, or drop by.
The average dose of methadone at most American clinics is 50 milligrams or less -- but research shows that optimal doses for most people are 60-120 mg. If your dose is not comfortable for you, it is not "addictive behavior" to want one that is. Doses of up to 1,000mg have been used successfully.
People considering detoxing from methadone should be aware that this is probably not a good idea for most people with HIV. Methadone-maintained addicts have slower progression to AIDS than those who are not on methadone, and street drugs can increase progression if you relapse after detox. Also, withdrawal itself is stressful to the body, and this can increase HIV replication and disease progression.
The following are some of the known drug interactions with methadone. There may be others -- this area, like most involving drug users, hasn't been well-studied yet. If you add a new medication and find that your methadone dose is not "holding" you or that it makes you drowsy or over-medicated, tell the counselor at your clinic. If they refuse to adjust your medication to meet your needs, ask your HIV care physician to discuss it with them. You shouldn't have to suffer because of ignorance about drug interactions from some clinic staff.
Currently, Dr. Ron D'Amico is studying interactions between protease inhibitors and methadone at Beth Israel Medical Center for AIDS Clinical Trials Group (ACTG) study number 401. He is offering participants $575 and HIV medications. You must already be on methadone. For further information, call (212) 844-1970.
Drugs that may make methadone more potent (stronger)
Fluconazole (Diflucan, a drug used to treat fungal infections) can raise methadone levels by 30%. In one study of this effect, no overdoses were reported. Ketaconazole (Nizoral) can have a similar effect.
The antidepressants amitriptyline (Elavil) and fluvoxamine (Luvox) can have a similar effect too, as can the anti-anxiety medication diazepam (Valium) and similar drugs like Xanax or Halcion.
Cimetidine (Tagamet), which is used in the treatment of ulcers and acid reflux heartburn), can also increase methadone levels as can urinary alkalinizers (Bicitra, Polycitra) used to treat gout and kidney stones.
Drugs with mixed/contradictory effects
Norvir (Ritonavir, a protease inhibitor) increases the potency of methadone when studied in the test tube-but in real life, it seems to have the opposite effect. If you're taking Norvir and your methadone isn't holding you, report it and ask for a raise in your methadone dose.
Crixivan (Indinavir, another protease inhibitor) seems to have a similar effect to Norvir -- it increases methadone in the test tube, but reduces it in the body, although the effect is not as pronounced as with Norvir.
Alcohol, when used regularly, can first increase, but later reduce the effectiveness of methadone treatment.
Drugs which make methadone less potent (weaker)
Rifampin (used to treat tuberculosis) can significantly decrease the length of time methadone stays in your system. Studies have found that methadone doses may need to be raised by 50% in order to be effective in people taking Rifampin. Be sure to report that you're taking this medication to your clinic. And if you feel like you're having withdrawal symptoms, increase your methadone dose.
Rifabutin (mycobutin, another TB drug) has effects similar to those of rifampin, but less severe. One study found that 75% of methadone patients taking Rifabutin reported mild withdrawal symptoms. Again, if these are bothering you and making you less likely to take your TB medications, have your methadone dosage increased.
Viramune (nevirapine) may require an increase in your methadone dose. There isn't much information available about this anti-HIV drug's interaction with methadone. One study showed that more than one-third of the people on Viramune required an increase in their methadone dose. If you feel like you're having withdrawal symptoms, increase your dose.
The anti-seizure medications carbamazepine (Tegretol) and phenytoin (Dilantin) (used to treat epilepsy) can also make methadone's effects less strong.
Doses of Vitamin C large enough to make the urine more acidic can also reduce methadone levels and effects. So be careful not to overdo the Vitamin C!
Drugs which methadone makes stronger
- AZT's potency has been found to be raised 50% by methadone. This means that if you take half as much AZT as someone who is not on methadone, you'll get the same HIV-fighting effect. If you're having bad side effects from AZT (Retrovir), this could be due to this interaction-you may have too much AZT in your system. Lowering your AZT dose may be in order.