LETTER TO THE EDITOR Paradoxical pinpoint pupils with asenapine Correspondence Jesjeet Singh Gill MBBS MPM, University Malaya, Psychological medicine, Faculty of Medicine, University Malaya, Kuala Lumpur 59100, Malaysia. Tel: +60126539703 Fax: +60379556477 Email: jesjeet@um.edu.my DOI:10.1111/appy.12171 Dear Editor, Atypical antipsychotics have been the mainstay of treatment in various indications, ranging from rapid tranquilization to maintenance treatment (Koh et al., 2010; Hui et al., 2013). Mydriasis can occur due to their anticholinergic effect. We report a case of para- doxical pinpoint pupils with asenapine. To the best of our knowledge, this is the first such reported case with asenapine, though they have been sporadic reports with other antipsychotics (O’Malley et al., 1999; Hodge et al., 2001). A 33-year-old woman was admitted in a manic state after defaulting her medication for over a year. She was started on asenapine 10 mg bid, sodium valproate 600 mg bid and lorazepam 1 mg tds. The next morning, she was noted to be drowsy but still conscious. Her vital signs, electrocardiography and oxygen saturation were normal. Physical examination revealed pinpoint pupils. All her medications were withheld, and by that evening, her consciousness level and pupillary response had returned to normal. The next day, sodium valproate was restarted and two days later, we restarted asenapine. However, she was again very drowsy with pinpoint pupils. Asenapine was withheld again, and she recovered over several hours. Later, risperidone was added and she gradually recovered. How asenapine caused miosis instead of mydriasis could probably be explained by its unique receptor profile. Asenapine has no appreciable affinity for muscarinic receptors (Ki of 8128 nM for M1) but exhibits high affinity toward α1A (Ki of 1.2) and α2A (Ki of 1.2) adrenoreceptor receptors (Saphris Product Monograph., 2012). This can cause miosis with no mydriatic action to counter it Psychiatrists need to be attuned to the possibility of such uncommon side effects in order to effectively treat our patients, otherwise we may investigate the cause down the wrong path, while continuing to give the offending medication. Jesjeet Singh Gill MBBS MPM, Stephen Jambunathan MBBS MPM, Sylvia Wong MD, & Angelvene Wong MBBS Department of Psychological Medicine, Faculty of Medicine, University Malaya, Kuala Lumpur 59100, Malaysia References Hodge C.H., Jewell M., Gummin D.D., et al. (2001) Atypical presentation of risperidone toxicity. Vet Hum Toxicol. 43(6), 339–341. Hui K.O., Sulaiman A.H., Gill J.S., et al. (2013) A 3-week, open label study to evaluate the efficacy and safety of extended release quetiapine fumarate in the treatment of agitation in patients with schizophrenia. Bull Clin Psychopharmacol. 23(1), 14–23. Koh O.H., Singh G.J., Kumar P.S., et al. (2010) Choice of antipsychotics prescribed for first episode psychotic patients in a teaching hospital. Int J Neuropsychopharmacol. 13, 98. O’Malley G.F., Seifert S., Heard K., et al. (1999) Olanzapine overdose mimicking opioid intoxication. Ann Emerg Med. 34(2), 279–281. Saphris Product Monograph (2012). Kirkland, QC, Merck Canada Inc. Official journal of the Pacific Rim College of Psychiatrists Asia-Pacific Psychiatry ISSN 1758-5864 230 Asia-Pacific Psychiatry 7 (2015) 230 © 2015 Wiley Publishing Asia Pty Ltd