Tolerance and dependance

Tolerance—a decrease in responsiveness—occurs when sedative hypnotics are used chronically or in high dosage. Cross-tolerance may occur among different chemical subgroups. Psychological dependence occurs frequently with most sedative-hypnotics and is manifested by the compulsive use of these drugs to reduce anxiety. Physiologic dependence constitutes an altered state that leads to an abstinence syndrome (withdrawal state) when the drug is discontinued. Withdrawal signs, which may include anxiety, tremors, hyperreflexia, and seizures, occur more commonly with shorter-acting drugs. The dependence liability of zolpidem, zaleplon, and eszopiclone may be less than that of the benzodiazepines since withdrawal symptoms are minimal after their abrupt discontinuance.