ABSTRACT
Dependency on a single drug is more the exception than the rule; multiple drug use has increased significantly since the late 1960s. Several patterns of multiple drug use can be identified (Table 17.1). Probably the most common pattern is typified by the alcohol drinker who also uses marijuana and other stimulant or depressant drugs. Another pattern results from unavailability of the primary drug, typically with regard to alcohol and other central nervous system depressants. Tranquilizers, barbiturates, or other sedatives are easily substituted for alcohol; heroin addicts who can't afford heroin may turn to such opiates as hydromorphone (Dilaudid), meperidine (Demerol), or street methadone. Multiple drugs are sometimes used to mask dependency on a person's primary drug. Alcoholics, for example, may take tranquilizers during the working day to maintain their equilibrium without smelling of alcohol. Other drugs are also used to prevent withdrawal when the primary drug is unavailable. Heroin addicts often drink excessive quantities of alcohol or take barbiturates or tranquilizers when they can't get heroin.
