Psychiatric effects of drugs for other disorders

Many drugs used therapeutically for non-psychiatric disorders can cause neuropsychiatric reactions. A wide range of such effects are reported including sedation, sleep disturbance, anxiety, depression, mania, psychosis, cognitive disturbance and delirium. The reactions are usually dose-related but may occur at therapeutic doses or on drug withdrawal after chronic use. They are more common in elderly or ill patients or those with a psychiatric history and may be unpredictable or paradoxical. Some of the more common psychiatric effects of drugs used for non-psychiatric disorders are reviewed briefly here. They include, among others, dopaminergic and antimuscarinic drugs for parkinsonism; digitalis and β-adrenoceptor antagonists for cardiovascular disorders; cannabinoid receptor antagonists for obesity; corticosteroids for endocrine disorders, asthma and allergic conditions; and anti-infective drugs for bacterial, parastic and viral infections.