Reactions 939 - 22 Feb 2003

SCitalopram

Syndrome of inappropriate antidiuretic hormonesecretion in an elderly patient: case report

A 92-year-old woman developed the syndrome ofinappropriate antidiuretic hormone secretion (SIADH) withsevere hyponatraemia, deep coma, seizure, atrial fibrillationand muscle damage after starting citalopram 20 mg/day fordepression. Her other medications at the time includedramipril, amlodipine and clopidogrel.

After receiving only two doses of citalopram, the womanwas found having a seizure. The seizure lasted for more than10 minutes and she subsequently remained unresponsive. Onexamination in the emergency department, she had a GlasgowComa Score of six, dilated pupils and an irregular pulse of 84beats/min. Her serum sodium level was 109 mmol/L (normal137–145), her serum osmolality was 229 mmol/kg (280–300),her chloride level was 79 mmol/L (98–111), her glucose levelwas 9.4 mmol/L (3.5–6), her urinary sodium level was 60mmol/L, her urinary osmolality was 494 mmol/kg and hercreatine kinase level was 988 U/L (20–200). An ECG showedatrial fibrillation at a rate of 78 beats/min and a CT scan of herbrain indicated mild cerebral oedema.

SIADH was suspected, and the woman was treated with aninfusion of sodium chloride. Citalopram was discontinued.Her serum sodium level increased gradually to 129 mmol/L 36hours after starting the infusion. A repeat ECG showedsupraventricular bigeminy at a rate of 82 beats/min, but sheconverted to sinus rhythm 8 hours later.

The woman was subsequently placed on fluid restriction. Byhospital day 3, she was alert and conversant, but confused.Her confusion gradually resolved during the next week. Herserum sodium level was 137 mmol/L or higher during the 4days after stopping fluid restriction. She was discharged 10days after admission and did not experience any furtheradverse effects during a 3-month follow-up period.

Author comment: "According to the algorithm for assessingthe probability of adverse drug reactions described by Naranjoet al., citalopram in our patient had a probable likelihood ofcausing SIADH with a score of 7 out of 10."Fisher A, et al. Citalopram-induced severe hyponatraemia with coma and seizure:case report with literature and spontaneous reports review. Adverse Drug Reactionsand Toxicological Reviews 21: 179-187, No. 4, 2002 - Australia 800868283

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Reactions 22 Feb 2003 No. 9390114-9954/10/0939-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved