Methadone, which is placed in the category of μ-opioid agonists, is often used in opioid addiction treatment programs. This PsycholoGenie write-up provides information on the mechanism of action along with the duration for which methadone stays in your system.
The number of clients receiving methadone in the opioid treatment programs (OTPs) regulated by Substance Abuse and Mental Health Services Administration (SAMHSA) increased from about 227,000 in 2003 to over 306,000 in 2011.
While methadone was developed in 1938, by German inventors and chemists Dr. Max Bockmühl and Dr. Gustav Ehrhart, it was in 1947 that this drug was introduced in the United States.
It is a long-acting synthetic opiate that was first used by the United States Public Health Services for opioid abstinence syndrome in the 1950s. In the 1960s, it began to be used as a part of the maintenance treatment of drug addiction in the United States. It is a μ-opioid agonist, which means that it activates μ-opioid (morphine-preferring) receptors in the nerve cells. Unlike buprenorphine, which is a partial-agonist, methadone is a full agonist.
Methadone doesn’t have a ceiling effect (effect of the drug doesn’t increase even with the increase in dosage at a certain point) like buprenorphine. Due to this reason, methadone is considered to be a better alternative for individuals dependent on high doses of opioids. This drug is available in the form of a tablet, liquid, or an injection.
As far as the elimination of any drug from the body is concerned, the kidneys remove the drugs and their metabolites (substances that form due to the metabolism of the drug by the liver) into urine. However, there are other ways by which the drugs might leave the body. For instance, drugs might leave the body in the form of sweat and breath. In fact, small amounts of drug might leave the system in the form of saliva and breast milk. There are several tests that can detect the presence of metabolites of the drug in the blood, urine, and saliva. Even drugs can be detected by using a hair sample. In fact, a hair sample can test positive for a drug, even if the last dose was taken six months ago. It must be noted that the excretion of unchanged methadone by kidneys in the form of urine is less than 10%.
Methadone has a long half-life (time taken for the plasma concentration of a drug to reach half of its original concentration) of 8 to 59 hours. It is a general rule that most drugs get completely eliminated from the body by 4-5 half-lives. Keeping this general rule in mind, this drug can get eliminated from the body by a couple of weeks. It could be detected in blood within 24 hours. However, different studies have shown that its half-life is quite variable, as it ranges from 8 to 59 hours. This drug can be detected in blood for 24 hours, and in the saliva for a period of 3-10 days after the last use. However, the rate at which it gets eliminated from the body could also vary, in the event of renal dysfunction, history of abuse, metabolism-related problems, etc. The rate of elimination can also vary, as this drug is known to accumulate in the liver and other tissues, after which it might be released slowly.
The active ingredient of this drug is methadone hydrochloride. Its pharmacological actions are very similar to that of morphine. Methadone maintenance therapy is recommended in case of individuals who are dependent on opiates, as the long-term administration of methadone hydrochloride helps in substituting the illicit drug, such as heroin, with methadone, which has a longer half-life. However, it must be noted that the outpatient maintenance and detoxification treatment needs to be provided only by Opioid Treatment Programs (OTPs) that are certified by the Federal Substance Abuse and Mental Health Services Administration (SAMHSA) and registered by the Drug Enforcement Administration (DEA).
The effects of methadone pills last longer, as it is a long-acting opioid with a long half-life. It has a good oral bioavailability, which refers to the extent of drug that is available to the target tissue after the administration of the drug. However, it must be noted that this drug can have adverse effects. Moreover, it can also cause an allergic reaction in case the user is allergic to any of the ingredients of the drug. In severe cases, one could develop anaphylaxis, which is a severe life-threatening allergic reaction that is characterized by the following symptoms:
✦ Swelling of the face, lips, tongue, and throat
✦ Shortness of breath
✦ Breathing difficulty
Medical assistance must be immediately sought in such cases. Moreover, serious problems could arise in case of an overdose. In fact, there have been cases where the conversion to methadone from long-term treatment with other opioid agonists even resulted in fatalities.
Other adverse effects that have been reported include:
✦ Chest pain
✦ Mood changes
✦ Sleep-related problems
✦ Abdominal pain
✦ Skin rashes
✦ Respiratory depression
There have been concerns about methadone regarding the fact that detox from methadone is more difficult than other opiates. While this opioid analgesic might help prevent the withdrawal symptoms, it is difficult to discontinue or taper off from the high doses, as the user is likely to experience pain. Also, the doctor needs to be informed about any other drug that one might be taking currently, as methadone could interact with other narcotic analgesics, seizure medication, diuretics, drugs for heart problems of blood pressure, MAO inhibitors, or drugs for HIV.
If methadone has been prescribed as a part of a treatment program, it must be taken as per the dosing schedule. Precautions must be taken, as methadone is a habit-forming drug. Do not discontinue the drug on your own. Keep it out of reach of children, and store it at room temperature, where it is not exposed to heat or moisture.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.