Reactions 1297 - 17 Apr 2010

SPregabalin

Confusion secondary to hyponatraemia in anelderly patient: case report

A 74-year-old man developed confusion secondary tohyponatraemia after starting pregabalin for neuropathicpain.

Following a below-knee amputation secondary tochronic osteomyelitis, the man received pregabalin [dosagenot stated] for neuropathic pain. His medical history wasalso notable for type 2 diabetes mellitus (insulindependent) complicated by diabetic retinopathy,neuropathy and nephropathy, and ischaemiccardiomyopathy with congestive heart failure. He had apacemaker and was receiving carvedilol [Dimitone], ACEinhibitors and loop diuretics. One week prior topresentation, he started to experience weakness, confusionand disorientation [duration of therapy before reaction notstated]. On admission, a physical examination was normalas were his lipid profile and liver, renal and thyroid functiontests. Laboratory investigations also revealed ahaemoglobin level of 10.1 g/dL, WBC and platelet counts of8300/µL and 245 000/

µL, respectively, sodium and potassium levels of 110 and4.40 mmol/L, respectively and serum osmolality of232 mOsm/kg (normal 265–275). His fasting cortisol levelwas 34.30 µg/dL, urinary sodium and potassium levelswere 145 and 29.40 mmol/L, respectively, and urineosmolality was 650 mOsm/kg. Mild pulmonary congestionand minimal left pleural effusion were evident on chest x-ray.

Pregabalin was discontinued and the man’s conditionwas managed with fluid restriction and administration of0.9% isotonic saline for 2 days. His sodium level increasedto 125 mmol/L and his confusion resolved. Two days later,his sodium level had further increased to 130 mmol/L.

Author comment: "[W]e used the Naranjo algorithm andfound that the confusion and worsening of the heart failurewith hyponatremia were most likely related to [pregabalin’s]side effects".Blum A, et al. Hyponatremia and confusion caused by pregabalin. Israel MedicalAssociation Journal 11: 699-700, No. 11, Nov 2009 - Israel 803010916

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Reactions 17 Apr 2010 No. 12970114-9954/10/1297-0001/$14.95 © 2010 Adis Data Information BV. All rights reserved