heroin /her″ō·in/ [Ger, heroine, originally trademark for diacetylmorphine] , a morphine-like drug with no currently acceptable medical use in the United States. Heroin is included in Schedule I of the Controlled Substances Act of 1970. Like other opium alkaloids, it can produce analgesia, respiratory depression, GI spasm, and physical dependence. It produces its major effects on the central nervous system and bowel and alters the endocrine and autonomic nervous systems. Heroin, which loses much of its analgesic power when taken orally, is more powerful than morphine and acts more rapidly. Repeated use of this drug produces tolerance to most of the acute opioid effects; physical dependence develops concurrently with tolerance. Withdrawal from heroin after relatively few exposures commonly produces acute abstinence syndrome. Withdrawal signs are usually observed shortly before the next planned dose and commonly include anxiety, restlessness, irritability, and craving for another dose. Other withdrawal signs that may appear 8 to 15 hours after the last dose include lacrimation, perspiration, yawning, and restless sleep. On awakening from such sleep the severely addicted heroin user may experience withdrawal signs, such as vomiting, pain in the bones, diarrhea, convulsions, and cardiovascular collapse. Withdrawal signs usually peak at between 36 and 48 hours and gradually subside during the following 10 days. Methadone is commonly used as a substitute drug in the treatment of heroin addiction (methadone maintenance therapy). Also called diacetylmorphine.
