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Indian Journal of Pharmacology, Vol. 41, No. 1, January-February, 2009, pp. 49-50 Case Report Pedal edema with olanzepine Nayak Veena, Chogtu Bharti, Devaramane Virupaksha, Bhandary PV Department of Pharmacology, Kasturba Medical College, Madhav Nagar, Manipal, Karnataka Date of Submission: 26-Jun-2008 Code Number: ph09012 Abstract Olanzapine, an atypical antipsychotic is considered superior to its conventional congeners. Here we report two cases of pedal edema secondary to olanzapine. In both cases the systemic causes of pedal edema were ruled out. On reducing the dose of olanzapine, pedal edema regressed and completely resolved after stopping the drug. So we attribute the edema to olanzapine therapy. As the definitive cause and further consequences of pedal edema are not known , hence stringent monitoring of adverse effects of this drug is required. Keywords: Olanzapine, pedal edema Introduction Olanzapine, an atypical antipsychotic is widely used in the treatment of psychiatric illnesses like schizophrenia, bipolar affective disorder etc. It is superior to haloperidol in controlling the negative symptoms of schizophrenia. The drug acts by antagonizing the serotonergic (5HT2A), dopaminergic (D2, D1, D4), muscarinic (M1) and histaminergic (H1) receptors. [1] Olanzapine is started with a dose of 5 to 10 mg per day. The most common side effects of this drug are weight gain and somnolence. [2] Other side effects include dry mouth, dizziness, constipation, dyspepsia, increased appetite, akathesia and tremors. In premarketing trials, peripheral edema was reported as an infrequent side effect, which affected 3% of the 532 olanzapine treated patients, as compared to 1% of the 294 subjects on placebo. [3] We present two cases of pedal edema due to olanzapine, which we came across in a private hospital.Case Reports Case 1 Review of literature revealed a few case reports of pedal edema due to olanzapine. On this basis, the dose of olanzapine was tapered and stopped in ten days. The edema subsided and disappeared over 20 days. The patient was then treated with risperidone 2 mg per day, for the psychotic symptoms. On subsequent follow up, the edema did not recur. Case 2 Discussion In both the cases discussed above, the edema can be attributed to olanzepine therapy, since the edema regressed when olanzapine was tapered and stopped. This also supports the earlier reports that it could be a dose related phenomenon. [4] As per the causality assessment, olanzapine as a causative agent for edema can be considered probable (Naranjo′s algorithm, score = 7). [5] In a case report of edema due to olanzapine, furosemide was added to treat the edema. [6] However, since this is a self limiting side effect, it does not require any intervention. Literature reports bilateral eyelid edema with olanzapine. [7] To explain the edema due to olanzapine, various hypotheses have been put forth. Firstly, the edema can be attributed to vasodilation and decrease in vascular resistance, which is secondary to blockade of a1 receptors by olanzapine. What can also lead to vasodilation is 5HT 2 blockade, through increasing cyclic adenosine monophosphate (cAMP). [4] Secondly, dopaminergic blockade due to olanzapine can alter the renal regulation of fluid and electrolytes, which play a role in producing edema. [8] Since other antipsychotics also share the same mechanisms, it is necessary to rigorously monitor the adverse events of this group as a whole. As per previous reports and our two case reports, we would like to conclude that edema due to olanzapine is not an infrequent side effect. Since this edema does not interfere with the underlying disease process and is self limiting, it is often overlooked by clinicians. References
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