Amobarbital abuse

Before the introduction of the benzodiazepines, a number of drugs from different chemical and pharmacological classes were used in the treatment of anxiety and insomnia. However, these drugs are more toxic and produce more serious side effects than do the benzodiazepines. Many also have signihcant abuse potential. Consequently, most of these compounds are no longer widely used. These drugs include the barbiturates (e.g., pentobarbital, amobarbital), carbamates (e.g., meprobamate), piperidinediones (e.g., glutethimide), and alcohols (e.g., ethchlorvynol). 

The CNS depressants include barbiturates, nonbarbiturate sedatives, and the benzodiazepines. As the medical use of barbiturates decreased, primarily because of their high addiction liability and the danger of acute lethality, the use of the benzodiazepine anxiolytics increased. The most commonly abused barbiturates are secobarbital, pentobarbital, and amobarbital. Pheno-barbital is not generally abused, because of its slow onset of action. The most commonly abused anxiolytics include diazepam, chlordiazepoxide, midazolam, lo-razepam, and flurazepam. These drugs are readily attainable from illicit sources. 

Aprobarbital is an elixir, mephobarbital is a tablet, and the drug containing secobarbital and amobarbital is a capsule. Legally prescribed barbiturates and those used in medical procedures are used in the form that the drug is produced. Some drug abusers will inject powder from capsules or ground-up tablets. 

Long-acting barbiturates include phenobarbital (Luminal) and mephobarbital (Mebaral). These drugs, which take effect in about one hour and last for about 12 hours, are used primarily for daytime sedation and the treatment of seizure disorders or mild anxiety. Generally, these are not drugs of abuse rather the short- and intermediate-acting barbiturates—such as amobarbital (Amytal), pentobarbital (Nembutal), and secobarbital (Seconal)—are among those most commonly abused. 

Several classes of pharmacologic agents are available for insomnia. Barbiturates are the oldest agents that have been used for insomnia and include pentobarbital, secobarbital, and amobarbital. Barbiturates are currently not recommended because of their high abuse potential (due to rapid development of tolerance) and lethal potential in overdose situations. Barbiturates potentiate the GABAergic-induced increase in chloride ion conductance at low doses, and at high doses they depress calcium-dependent action potentials. Caution should be exercised in patients with marked renal or liver dysfunction, severe respiratory disease, suicidal tendencies, or history of alcohol/drug abuse. 

Schedule 11 drugs have an accepted medical use in the United States and a high rate of abuse, with either severe psychological or physical dependence potential. These drugs include morphine, codeine, cocaine, amphetamine, and most barbiturate preparations containing amobarbital, secobarbital, and pentobarbital. 

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