13-cis retinoyl-beta-glucuronide in lacrimal gland fluid of rabbits treated with 13-cis retinoic acid.

When rabbits and humans are treated with orally administered 13-cis retinoic acid, the retinoic acid and a more polar retinoid metabolite appear in tears and lacrimal gland fluid. This study tested the hypothesis that this metabolite was a retinoyl-beta-glucuronide. Lacrimal gland fluid from rabbits treated with a pharmacologic dose of 13-cis retinoic acid was analyzed. Based on chromatographic retention time, absorbance maximum, and degradation to 13-cis retinoic acid by the enzyme beta-glucuronidase, it was shown that this retinoid metabolite is 13-cis retinoyl-beta-glucuronide. The 13-cis retinoyl-beta-glucuronide was also extracted from the lacrimal gland itself. It is concluded that 13-cis retinoyl-beta-glucuronide is a major metabolite of 13-cis retinoic acid in the rabbit and that this retinoid is secreted by the lacrimal gland.