Benzodiazepines are a class of drugs that produce central nervous system (CNS) depression and that are most commonly used to treat insomnia and anxiety. There is the potential for dependence on and abuse of benzodiazepines particularly by individuals with a history of multi-substance abuse. Alprazolam (e.g., Xanax), lorazepam (e.g., Ativan), clonazepam (e.g., Klonopin), diazepam (e.g., Valium), and temazepam (e.g., Restoril) are the five most prescribed, as well as the most frequently encountered benzodiazepines on the illicit market.

All benzodiazepines are composed of a benzene ring and a seven-member diazepine ring. Most benzodiazepines also possess a phenyl ring attached at the 5-position of the diazepine ring. Small modifications of this basic structure account for the varied pharmacologic effects of these drugs.

Benzodiazepines produce CNS depression by enhancing the effects of the major inhibitory neurotransmitter, gamma-aminobutyric acid, thereby decreasing brain activity. Benzodiazepines are classified by their duration of action that ranges from less than 6 hours to more than 24 hours. Some benzodiazepines have active metabolites that prolong their effects.

Adverse effects include increased reaction time, motor incoordination, anterograde amnesia, slurred speech, restlessness, delirium, aggression, depression, hallucinations, and paranoia. Unlike barbiturates, large doses of benzodiazepines are rarely fatal unless combined with other CNS depressant drugs, such as alcohol or opioids. Flumazenil can be administered by injection to reverse the adverse effects of benzodiazepines.

Tolerance often develops after long term use requiring larger doses to achieve the desired effect. Physical and psychological dependence may develop, whether taken under a doctor’s orders or used illicitly. Withdrawal symptoms, the severity of which is dependent on the dose, duration of use, and particular drug used, include anxiety, insomnia, dysphoria, tremors, and seizures. Withdrawal can be precipitated by the administration of flumazenil to individuals dependent upon benzodiazepines.

Benzodiazepines, particularly those having a rapid onset, are abused to produce a euphoric effect often described as a "high." Abuse of benzodiazepines is often associated with multiple-substance abuse. Diazepam and alprazolam are used in combination with methadone to potentiate methadone’s euphoric effect. Cocaine addicts use benzodiazepines to relieve the side effects (e.g., irritability and agitation) associated with cocaine binges. Benzodiazepines are also used to augment alcohol’s effects and modulate withdrawal states. The doses of benzodiazepines taken by abusers are usually in excess of the recommended therapeutic dose. Benzodiazepines have been used to facilitate sexual assault.

Individuals abusing benzodiazepines obtain them by getting prescriptions from several doctors, forging prescriptions, or buying diverted pharmaceutical products on the illicit market. Domestic and foreign products are found in the illicit market. Alprazolam is one of the top three prescription drugs illegally encountered. In 2006, as reported by the National Forensic Laboratory Information System, state and local drug laboratories analyzed 24,057 alprazolam, 6,360 clonazepam, 5,886 diazepam, 1,444 lorazepam, and 333 temazepam exhibits. In 2006, the DEA drug laboratories, as reported in the System to Retrieve Information from Drug Evidence system, analyzed 384 alprazolam, 107 clonazepam, 179 diazepam, 60 lorazepam, and 22 temazepam exhibits.

Benzodiazepines are classified as schedule IV depressants under the Controlled Substances Act. Flunitrazepam is unique among the benzodiazepines in being placed in schedule IV but having schedule I penalties.