Reactions 569 - 23 Sep 1995

Carbamazepine

Hyponatraemia: case reportCarbamazepine-induced hyponatraemia can be successfully

reversed with concomitant doxycyline, as described in thefollowing case report.

A 38-year-old woman with a history of schizoaffectivedisorder and hypothyroidism was admitted with psychoticsymptoms and delusions. On admission (day 1), hermedications comprised oral carbamazepine 200mg tid,fluphenazine, clonazepam, benzatropine and levothyroxine.However, she had a history of noncompliance, and her plasmacarbamazepine concentration on day 1 was 0.1 ng/ml(therapeutic range 5–10 ng/ml). Her serum sodium level was136mEq/L and she had normal thyroid function.

The woman’s medications were restarted and on day 21,with a carbamazepine dosage of 1000 mg/day, her serumcarbamazepine concentration was 8.4 ng/ml. Her serumsodium level was 129 mEq/L. Two days later, her serumsodium level had decreased to 125 mEq/L, but she remainedasymptomatic. On day 26, the woman started therapy withoral doxycycline 100mg bid for a cervical infection and thefollowing day, her serum carbamazepine concentration was6.9 ng/ml and her serum sodium level was 131 mEq/L. Twodays later, these parameters were 8.1 ng/ml and 132 mEq/L,respectively.

The patient completed doxycyline therapy on day 32 and onday 35, her serum sodium level had decreased to 125 mEq/L.Carbamazepine was tapered and replaced with valproic acidtherapy and her serum sodium level normalised.

Author comment: Another tetracycline antibacterial agent,demeclocycline has been shown to correct carbamazepine-induced hyponatraemia. However, doxycyline may be a usefulalternative treatment, since it has a longer half-life and does notcause renal toxicity.Boutros NN, et al. Carbamazepine-induced hyponatremia resolved withdoxycycline. Journal of Clinical Psychiatry 56: 377-378, Aug 1995 -USA 800389906

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Reactions 23 Sep 1995 No. 5690114-9954/10/0569-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved