Meclizine seasickness medication and its effect on central nervous system oxygen toxicity in a murine model

Abstract

Introduction: Diving utilising closed circuit pure oxygen rebreather systems has become popular in professional settings. One of the hazards the oxygen diver faces is central nervous system oxygen toxicity (CNS-OT), causing potentially fatal convulsions. At the same time, divers frequently travel by boat, often suffering seasickness. The over-the-counter medication meclizine is an anticholinergic and antihistaminergic agent that has gained popularity in the treatment of seasickness. Reports have shown the inhibitory effect that acetylcholine has on glutamate, a main component in the mechanism leading to CNS-OT seizure. The goal of the present study was to test the effect of meclizine on the latency to CNS-OT seizures under hyperbaric oxygen conditions.

Methods: Twenty male mice were exposed twice to 608 kPa (6 atmospheres) absolute pressure while breathing oxygen after administration of control solution (carboxymethyl cellulose solvent) or drug solution (meclizine) in a randomised crossover design. Latency to tonic-clonic seizures was visually measured.

Results: Mean latency to seizure did not significantly differ between the control group (414 s, standard deviation [SD] 113 s) and meclizine group (434 s, SD 174 s).

Conclusions: Based on results from this animal model, meclizine may be an appropriate option for divers suffering from seasickness, who plan on diving using pure oxygen rebreather systems.

Keywords: Cholinergic antagonists; Closed circuit rebreathers; Diving; Histamine antagonists; Seizures.

Figure 1

Exposure profile of mice to hyperbaric oxygen conditions, and measurement of latency to onset of tonic-clonic seizures; during pressurisation, air is gradually switched to oxygen, and during decompression the oxygen is switched back to air. kPa − kilopascals; min – minutes; O₂ – oxygen

Figure 2

Latency for individual subjects for control and meclizine-treatment conditions. s – seconds

Figure 3

Latency versus mass of mice; oxygen toxicity latency did not vary with mass for either control (solid line) or meclizine-treatment (dashed line) groups. s – seconds; g – grams