Conivaptan for hyponatremia in the neurocritical care unit.

INTRODUCTION: Conivaptan is the first arginine vasopressin antagonist to be FDA-approved for the treatment of euvolemic hyponatremia, a common complication in neurointensive care patients. Due to risks for cerebral edema and seizures, sodium levels are generally aggressively maintained within normal levels (135-145 meq/l) in this patient population. OBJECTIVE: To assess the safety and efficacy of conivaptan for the treatment of euvolemic hyponatremia in the neurocritical care unit. METHODS: Data were obtained retrospectively on 22 patients treated with conivaptan for euvolemic hyponatremia. End points evaluated included time to [Na] increase of >or=6 meq/l; incidences of rapid overcorrection of [Na] (defined as an increase of >12 meq/l in a 24-h period while on conivaptan), infusion site reactions, or other adverse events; and whether sodium levels decreased after discontinuation of conivaptan. RESULTS: A [Na] increase of >or=6 meq/l was reached in 19/22 (86%) patients, with an average time to goal of 13.1 h. No patients experienced a rapid overcorrection of [Na]. Five patients had an infusion site reaction necessitating an IV change. One patient experienced hypotension and another complained of thirst during infusion. Conivaptan was initiated in 11/22 patients (50%) who were hyponatremic despite already being on conventional therapies. CONCLUSION: Conivaptan was safe and effective in this small series of neurointensive care patients, including many patients who were hyponatremic despite traditional treatments to maintain normal sodium levels. Further studies are needed to clarify the role of conivaptan as an adjunctive and/or alternative therapy for hyponatremia in this patient population.

Peripheral neuropathy associated with prolonged use of linezolid.

We present a case of a woman who developed severe, painful peripheral neuropathy while receiving linezolid therapy for 6 months. Nerve conduction studies indicated a sensory-motor axonal neuropathy. Extensive assessment did not show alternative explanations for her neuropathy. At the time of death 1 month after discontinuing linezolid, the neuropathy had not resolved. A review of published material shows a growing body of evidence that long-term use of linezolid may be associated with severe peripheral and optic neuropathy. 21 cases have been reported. In most cases, optic neuropathies resolved after stopping linezolid but peripheral neuropathies did not. The duration of therapy rather than indication for treatment seems to be the most important factor. The mechanism of toxicity is unknown but certain pharmacological properties of linezolid that may play a part are proposed. This report highlights the importance of post-approval surveillance and reporting of serious adverse drug effects, and potential consequences of off-label use of pharmaceuticals. It further demonstrates the critical role clinicians have in communicating awareness of emerging drug toxicities.