Abstract

Aims: We investigated the effect of several Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), on the preoptic nerve oxygen tension (ONPo₂), as indomethacin previously has demonstrated a strong decreasing effect on ONPo₂. We tested whether these NSAIDs, like indomethacin, also reduce the increasing effect of dorzolamide on ONPo₂.

Methods: ONPo₂ was measured 0.5 mm above the optic disc in 23 domestic pigs (26–36 kg) with a polarographic oxygen-sensitive electrode. One of the following NSAIDs was administered intravenously as increasing doses or as one large dose: indomethacin, ibuprofen, diclofenac, ketoprofen, parecyclo-oxygenase-2 inhibitor and lornoxicam. Indomethacin was both tested alone and after preceding administration of the other NSAIDs. Dorzolamide was also tested after preceding administration of NSAIDs different from indomethacin.

Results: Indomethacin decreased ONPo₂ significantly in a dose-dependent manner. None of the other NSAIDs produced any effect on the ONPo₂ (p>>0.05; n = 17). No difference was found between the effect of indomethacin injected alone, and after preceding administration of the other NSAIDs. Intravenous dorzolamide (500 mg) increased ONPo₂ by 32 (7)% (n = 7; p<0.001) after preceding administration of several NSAIDs different from indomethacin.

Conclusions: Indomethacin decreased ONPo₂, while the other NSAIDs showed no effect on ONPo₂, and they did not affect the effect of indomethacin. The hypoxic effect of indomethacin must be due to another mechanism than cyclo-oxygenase inhibition. The effect of dorzolamide on ONPo₂ is not related to prostaglandin production.