Abstract
Olanzapine, an atypical antipsychotic, has been found to be effective in control of psychosis and aggression. Considering its lesser propensity for dystonia and extrapyramidal adverse effects than typical antipsychotics, intramuscular preparations of olanzapine have been used in treatment of acute affective psychosis in adults [1]. However, data describing its use in children and adolescents are meagre. The present case report describes acute dystonia in an adolescent following treatment with intramuscular olanzapine.
AY, a 16-year-old boy with a DSM-IV diagnosis of manic episode with psychotic symptoms was treated with intramuscular olanzapine. Rapid-acting intramuscular formulation of olanzapine has a more rapid rate of absorption, as shown by higher maximal concentration (Cmax) (two- to five folds) and an earlier time to Cmax (30min vs 4 h) than oral formulation [2]. Hence, treatment was commenced with intramuscular olanzapine (10mg b.i.d.) for prominent psychotic symptoms, aggression and agitation. Additionally, its mood stabilizing property was also considered. After 45minutes of the first dose, hyperextension of the trunk was observed. Physical examination revealed tightening of the muscles of the back. A possibility of truncal dystonia was made and immediately treated with intramuscular promethazine 50 mg, following which dystonia resolved within 15 minutes. The patientwas continued on olanzapine for the next 2 days with which, he developed tremors, bradykinesia and rigidity. Regular anticholinergics (trihexyphenidyl, 4 mg day−1) were started with which he showed significant improvement.
Although there are reports of dystonia with oral olanzapine [3], the present report shows that dystonic reactions can also occur with intramuscular olanzapine in adolescents. Pathophysiology of acute dystonic reactions involves increased dopamine synthesis and release, especially as neuroleptic levels in the blood and brain decline [4]. Younger age with faster drug elimination in the paediatric group, male sex and presence of affective disorder might be possible risk factors in our case. Also, the report highlights the increased chances of further development of extrapyramidal symptoms in cases, experiencing dystonic reactions early in the course of treatment. Further reports and well-designed trials are necessary considering the potential of intramuscular olanzapine as a firstline choice in acute psychosis and agitation. This calls for a very cautious approach for its use in children and adolescents.