Drug-induced dystonia
Drug-induced dystonia (DID) is a rarely diagnosed adverse reaction to a sufficiently large number of drugs. Acute DID (ADID) occurs soon after starting to take a drug or raising its dose, and switching from one antipsychotic medication to another, especially to its injectable dosage form. Tardive DID (TDID) develops a few months or years after starting drug intake or 3 months after stopping therapy. The diagnosis of TDID is based on the persistence of dystonic hyperkinesis for more than 1 month, the use of a dopamine receptor blocking agent, and the absence of other causes of its development. The risk factors for DID are male sex; young age (less than 30 years of age); a history of dystonic reactions; hypocalcemia, alcohol use while taking the drug. DID is most commonly related to therapy with antipsychotics, metoclopramide, antidepressants, and antiepileptic drugs. The short-term use of anticholinergic drugs (benzotropin, diphenhydramine) is effective in treating ADID. Anticholinergic drugs and atypical antipsychotics (clozapine, quetiapine), benzodiazepines, muscle relaxants (baclofen), and dopamine reuptake inhibitors (tetrabenazine) are used to treat TDID. To prevent DID, it is very important that a physician should be aware of that this unwanted adverse reaction may occur and that a drug with the lowest risk for DID should be chosen.