Phenytoin: ineffective against acute mountain sickness.

Area of Science:

• Altitude Medicine
• Neuropharmacology

Background:

• Acute mountain sickness (AMS) is a common condition at high altitudes.
• A hypothetical cause of AMS involves increased intracellular brain volume due to ion shifts.
• Phenytoin sodium is known to reduce intracellular sodium concentrations.

Purpose of the Study:

• To investigate the efficacy of phenytoin sodium in preventing or reducing the severity of acute mountain sickness.
• To assess phenytoin's impact on AMS symptoms such as headache, nausea, insomnia, and malaise.

Main Methods:

• A double-blind, crossover study involving six healthy men exposed to simulated altitude (4600 m) in a hypobaric chamber.
• Subjects received phenytoin or placebo before and during altitude exposure.
• Symptom severity and other physiological parameters were assessed using questionnaires and clinical evaluations.

Main Results:

• Phenytoin did not demonstrate a marked benefit in the occurrence, severity, or duration of AMS symptoms.
• Three subjects reported moderate weakness and dizziness with phenytoin, which were not reported with placebo.
• No correlation was found between phenytoin serum levels and AMS symptom severity.

Conclusions:

• Phenytoin sodium was not found to be effective in managing acute mountain sickness under the tested conditions.
• The drug did not improve AMS symptoms and was associated with some adverse effects like weakness and dizziness.