Reactions 1044 - 26 Mar 2005

★ O SCitalopram overdose

First report of junctional bradycardia treated withsodium bicarbonate in an elderly patient: casereport

An 82-year-old woman developed junctional bradycardiaafter intentional ingestion of a citalopram overdose;bradycardia was reversed following treatment with IV sodiumbicarbonate.

The woman, who had a history of depression, wasdiscovered 12 hours after ingesting citalopram 1.6g in asuicide attempt. A generalised tonic-clonic seizure waswitnessed and, on admission, she was postictal, with a BP of148/66mm Hg, a HR of 61 beats/min, a respiratory rate of20 breaths/min and a temperature of 36.2°C. Her Mini-MentalState Examination score was 22, and an ECG showed sinusbradycardia, a ventricular rate of 58 beats/min, left axisdeviation and left bundle branch block, consistent withprevious ECGs. Her QRS duration and QT and QTc intervalswere 146, 544 and 534 msec, respectively. Laboratoryinvestigations revealed a serum citalopram concentration of910 ng/mL (therapeutic range ≤ 120 ng/mL). She becameincreasingly alert over the next 3 hours and was transferred formonitoring of her prolonged QT-QTc intervals. Three hourslater, she developed marked bradycardia and an ECG showeda junctional escape rhythm, a ventricular rate of 40 beats/min,retrograde ventriculoatrial activation and underlying leftbundle branch block. Her QRS duration increased to 152 msecand her QT and QTc intervals increased to 646 and 527 msec,respectively.

The woman received a sodium bicarbonate 50 mEq injection(50mL of an 8.4% solution) and, within 5 minutes, her QRSduration decreased to 142 msec. There was promptconversion to a nonsinus atrial rhythm, with a ventricular rateof 80 beats/min and a normal PR interval. These changes lastedfor approximately 3 minutes before reverting to junctionalbradycardia. She received a second sodium bicarbonateinjection, with a similar transient effect. A continuous infusionof sodium bicarbonate 150 mEq in 1L of 5% dextrose wasstarted and, within 3 hours, normal sinus rhythm returned,with a HR of 63 beats/min and QT and QTc intervals of 510and 504 msec, respectively. The infusion was stopped after36 hours, without recurrence of the ECG abnormalities.Brucculeri M, et al. Reversal of citalopram-induced junctional bradycardia withintravenous sodium bicarbonate. Pharmacotherapy 25: 119-122, No. 1, Jan 2005 -USA 801001501

» Editorial comment: A search of AdisBase and Medline didnot reveal any previous case reports of junctional bradycardiaassociated with citalopram. The WHO Adverse Drug Reactionsdatabase contained 76 reports of bradycardia associated withcitalopram.

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Reactions 26 Mar 2005 No. 10440114-9954/10/1044-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved