DEA, Drug Information, Other Drugs: M

Meperidine
Introduced as an analgesic in the 1930s, meperidine produces effects that are similar, but not identical, to morphine (shorter duration of action and reduced antitussive and antidiarrheal actions). Currently it is used for pre-anesthesia and the relief of moderate to severe pain, particularly in obstetrics and post-operative situations. Meperidine is available in tablets, syrups, and injectable forms under generic and brand name (Demerol®, Mepergan®, etc.) Schedule II preparations. Several analogues of meperidine have been clandestinely produced. During the clandestine synthesis of the analogue MPPP, a neurotoxic by-product (MPTP) was produced. A number of individuals who consumed the MPPP-MPTP preparation developed an irreversible Parkinsonian-like syndrome. It was later found that MPTP destroys the same neurons as those damaged in the Parkinsonian-like syndrome. It was later found that MPTP destroys the same neurons as those damaged in Parkinsons Disease.

Meprobamate
Meprobamate was introduced as an anti-anxiety agent in 1955 and is prescribed primarily to treat anxiety, tension, and associated muscle spasms. More than 50 tons are distributed annually in the United States under its generic name and brand names such as Miltown® and Equanil®. Its onset and duration of action are similar to the intermediate-acting barbiturates; however, therapeutic doses of meprobamate produce less sedation and toxicity than barbiturates. Excessive use can result in psychological and physical dependence. Carisoprodol (Soma®), a skeletal muscle relaxant, is metabolized to meprobamate. This conversion may account for some of the properties associated with carisoprodol and likely contributes to its abuse.

Methadone
German scientists synthesized methadone during World War II because of a shortage of morphine. Although chemically unlike morphine or heroin, methadone produces many of the same effects. Introduced into the United States in 1947 as an analgesic (Dolophinel), it is primarily used today for the treatment of narcotic addiction. It is available in oral solutions, tablets, and injectable Schedule II formulations, and is almost as effective when administered orally as it is by injection. Methadone's effects can last up to 24 hours, thereby permitting once-a-day oral administration in heroin detoxification and maintenance programs. High-dose methadone can block the effects of heroin, thereby discouraging the continued use of heroin by addicts under treatment with methadone. Chronic administration of methadone results in the development of tolerance and dependence. The withdrawal syndrome develops more slowly and is less severe but more prolonged than that associated with heroin withdrawal. Ironically, methadone used to control narcotic addiction is frequently encountered on the illicit market and has been associated with a number of overdose deaths.

Methcathinone
Methcathinone, known on the streets as "Cat," is a structural analogue of methamphetamine and cathinone. Clandestinely manufactured, methcathinone is almost exclusively sold in the stable and highly water soluble hydrochloride salt form. It is most commonly snorted, although it can be taken orally by mixing it with a beverage or diluted in water and injected intravenously. Methcathinone has an abuse potential equivalent to methamphetamine and produces amphetamine-like activity. It was placed in Schedule I of the CSA in 1993.

Methylphenidate
Methylphenidate, a Schedule II substance, has a high potential for abuse and produces many of the same effects as cocaine or the amphetamines. The abuse of this substance has been documented among narcotic addicts who dissolve the tablets in water and inject the mixture. Complications arising from this practice are common due to the insoluble fillers used in the tablets. When injected, these materials block small blood vessels, causing serious damage to the lungs and retina of the eye. Binge use, psychotic episodes, cardiovascular complications, and severe psychological addiction have all been associated with methylphenidate abuse.

Methylphenidate is used legitimately in the treatment of excessive daytime sleepiness associated with narcolepsy, as is the newly marketed Schedule IV stimulant, modafinil (Provigil®). However; the primary legitimate medical use of methylphenidate (Ritalin®, Methylin®, Concerta®) is to treat attention deficit hyperactivity disorder (ADHD) in children. The increased use of this substance for the treatment of ADHD has paralleled an increase in its abuse among adolescents and young adults who crush these tablets and snort the powder to get high. Youngsters have little difficulty obtaining methylphenidate from classmates or friends who have been prescribed it. Greater efforts to safeguard this medication at home and school are needed.

Morphine
Morphine is the principal constituent of opium and can range in concentration from 4 to 21 percent. Commercial opium is standardized to contain 10-percent morphine. In the United States, a small percentage of the morphine obtained from opium is used directly (about 15 tons): the remaining is converted to codeine and other derivatives (about 120 tons). Morphine is one of the most effective drugs known for the relief of severe pain and remains the standard against which new analgesics are measured. Like most narcotics, the use of morphine has increased significantly in recent years. Since 1990, there has been about a 3-fold increase in morphine products in the United States.

Morphine is marketed under generic and brand name products including "MS-Contin®," Oramorph SR®," MSIR®," Roxanol®," Kadian®," and RMS®." Morphine is used parenterally (by injection) for preoperative sedation, as a supplement to anesthesia, and for analgesia. It is the drug of choice for relieving pain of myocardial infarction and for its cardiovascular effects in the treatment of acute pulmonary edema. Traditionally; morphine was almost exclusively used by injection. Today, morphine is marketed in a variety of forms, including oral solutions, immediate and sustained-release tablets and capsules, suppositories, and injectable preparations. In addition, the availability of high-concentration morphine preparations (i.e., 20-mg/ml oral solutions, 25-mg/ml injectable solutions, and 200-mg sustained-release tablets) partially reflects the use of this substance for chronic pain management in opiate-tolerant patients.