Psychopharmacology in medical practice

Psychotropic drugs play an indispensable role in the treatment of severe psychiatric illness such as schizophrenia and bipolar disorder. They are often used to treat other conditions, particularly depression and anxiety disorders, but for these disorders nondrug treatments are effective and—if available—are often preferred by patients.

Antidepressants—newer drugs, particularly selective serotonin reuptake inhibitors (SSRIs), have replaced traditional tricyclic antidepressants in the treatment of depression. These are somewhat better tolerated and, with the exception of venlafaxine, are safer in overdose. All patients should be monitored carefully following the introduction of antidepressant medication because the risk of suicidal behaviour appears to be higher at this time. Patients with recurrent depression often benefit from maintenance treatment with antidepressants.

Lithium—this continues to be the leading mood stabilizing agent prescribed for the treatment of bipolar disorder in the United Kingdom, but it has significant adverse effects that particularly involve the kidneys and central nervous system. It also has a narrow therapeutic index and drug interactions carry a high risk of serious toxicity. For these reasons there is growing use of anticonvulsant drugs such as sodium valproate as alternatives to lithium.

Antipsychotics—in the treatment of schizophrenia, atypical antipsychotic drugs are replacing conventional agents such as haloperidol and chlorpromazine because of their better perceived adverse effect profile, particularly with regard to extrapyramidal movement disorders. However, some atypical agents, particularly clozapine and olanzapine, cause excessive weight gain and have been linked with type 2 diabetes and disturbances in lipid metabolism. Of these agents, only clozapine has clearly superior efficacy relative to conventional agents, but it carries a risk of agranulocytosis and hence the need for weekly blood count monitoring complicates its use.

Benzodiazepines—use of these drugs for the treatment of anxiety and insomnia continues to decline because of their recognized liability to cause tolerance and dependence. They are indicated only for short-term use, preferably on an as needed basis. The same advice applies to other hypnotic agents such as the ‘Z’ drugs. Where psychological treatments are not effective or unavailable, antidepressants treatment—particularly with SSRIs—can be used to treat a range of anxiety disorders, including obsessive–compulsive disorder.