Acetaminophen

Acetaminophen, nonprescription drug used for the relief of minor pain, such as headaches and structural muscle aches, and for the reduction of fever. Like the other common analgesic drugs aspirin and ibuprofen, acetaminophen relieves pain by inhibiting the synthesis of prostaglandins in the body. It does not reduce inflammation as do those other two analgesics, but it also does not irritate the stomach lining, as aspirin tends to do for some users. A large overdose of acetaminophen may cause severe liver damage.

Aspirin

Aspirin, synthetic chemical compound, acetylsalicylic acid. It is made from salicylic acid, found in the bark of the willow tree, which was used by the ancient Greeks and Native Americans, among others, to counter fever and pain. Salicylic acid is bitter, however, and irritates the stomach. The German chemist Felix Hoffman synthesized the acetyl derivative of salicylic acid in 1893 in response to the urging of his father, who took salicylic acid for rheumatism. Aspirin is currently the first-choice drug for fever, mild to moderate pain, and inflammation due to arthritis or injury. It is a more effective analgesic than codeine. Aspirin causes insignificant gastrointestinal bleeding that can over time, however, cause iron deficiency; gastric ulcers may also occur with long-term use. Complications can be avoided by using enteric-coated aspirin, which does not dissolve until reaching the intestine. Aspirin should not be given to children who have chicken pox or influenza, because it increases the risk of contracting the rare and frequently fatal Reye's syndrome, a disease of the brain and some abdominal organs.

Aspirin is thought to act by interfering with synthesis of prostaglandins, which are implicated in inflammation and fever. Studies of aspirin's anticlotting activities suggest that half an aspirin tablet per day may reduce the risk of heart attack and stroke in some persons.

Opium

Opium, narcotic drug produced from the drying resin of unripe capsules of the opium poppy, Papaver somniferum. Opium is grown mainly in Myanmar (formerly Burma) and Afghanistan. The legitimate world demand for opium amounts to about 680 metric tons a year, but many times that amount is distributed illegally.

In its commercial form, opium is a chestnut-colored globular mass, sticky and rather soft, but hardening from within as it ages. It is processed into the alkaloid morphine which has long served as the chief painkiller in medical practice, although synthetic substitutes such as meperidine (trade name Demerol) are now available. Heroin, a derivative of morphine, is about three times more potent. Codeine is another important opium alkaloid.

The molecules of opiates have painkilling properties similar to those of compounds called endorphins or enkephalins produced in the body. Being of similar structure, the opiate molecules occupy many of the same nerve-receptor sites and bring on the same analgesic effect as the body's natural painkillers. Opiates first produce a feeling of pleasure and euphoria, but with their continued use the body demands larger amounts to reach the same sense of well-being. Withdrawal is extremely uncomfortable, and addicts typically continue taking the drug to avoid pain rather than to attain the initial state of euphoria. Malnutrition, respiratory complications, and low blood pressure are some of the illnesses associated with addiction.

Narcotics

Narcotics, term originally applied to all compounds that produce insensibility to external stimuli through depression of the central nervous system, but now applied primarily to the drugs known as opiates—compounds extracted from the opium poppy and their chemical derivatives. Also classed as narcotics are the opioids, chemical compounds that are wholly synthesized, but which resemble the opiates in their actions.

The most important attribute of narcotics is their capacity to decrease pain, not only by decreasing the perception of pain, but also by altering the reaction to it. Although they do have sedative properties when used in large doses, they are not used primarily for sedation.

The major constituent of opium and the prototype of all narcotic analgesics is morphine, which was isolated and chemically analyzed by the German apothecary F. W. A. Setürner between 1805 and 1817. Other narcotics used in the U.S. are meperidine (trade name Demerol), codeine, and propoxyphene (trade name Darvon). Heroin, synthesized from morphine, is a potent analgesic, but its use is forbidden in the U.S. Some of the newer synthetic compounds are 1000 to 10,000 times more potent than morphine.

In addition to their painkilling properties, the narcotic analgesics cause a profound feeling of well-being (euphoria). It is this feeling that is in part responsible for the psychological drive of certain persons to obtain and self-administer these drugs. When taken chronically in large doses, the narcotics have the capacity to induce tolerance (whereby a larger and larger dose is required by the body to achieve the same effect), and ultimately psychological and physical dependence, or addiction. In this respect they are similar to the barbiturates and to alcohol. These properties make the medical use of narcotics extremely difficult and have led to strict regulation of the prescription and dispensing of this class of drugs. Even so, they are widely abused. See Drug Dependence.

Sedative

Sedative, any of the drugs used to reduce nervous tension or induce sleep. Often referred to as sedative-hypnotic drugs, these substances generally have a calming and relaxing effect on the central nervous system and muscles when taken in small doses, and a hypnotic, or sleep-producing, effect when taken in larger doses. For centuries alcohol and opium were the only substances known to produce these effects, but in recent decades over 50 other substances have been discovered, each differing slightly in its effect on the user. Among the sedatives prescribed for calming patients are the tranquilizers Librium (chlordiazepoxide hydrochloride) and Valium (diazepam), which are commonly used to relieve emotional stress (see Anxiety; Tranquilizer). Drugs administered to produce sleep include barbiturates such as secobarbital, pentobarbital, and phenobarbital, which produce short, medium, and prolonged durations of sleep, respectively. Chloral hydrate, paraldehyde, antihistamine, and Quaalude (methaqualone) are other sedative-hypnotic drugs.

Sedatives are habit-forming and can cause severe addiction problems. Easily obtainable from physicians, they have become, since the 1960s, among the most abused drugs. See Drug Dependence.