Temarotene (Ro 15-0778) is an orally active and potent small molecule compound that modulates human immune function in vitro.Temarotene may be used in the study of lichen planus.

The study examines how retinoids regulate ornithine decarboxylase (ODC) gene expression in human keratinocyte cultures grown in a serum-free environment with 0.15 mM Ca2+. Keratinocytes were treated with varying concentrations (0.1 nM to 10 μM) of all-trans-retinoic acid, 13-cis-retinoic acid, or arotinoid Ro15-0778. Following a 24-hour treatment, a dose-dependent decrease in ODC mRNA levels was observed, with both types of retinoic acids showing an estimated half-maximal inhibitory concentration (IC50) of about 10 nM, and Ro15-0778 being slightly less potent with an IC50 of approximately 0.1-0.5 μM. This suppression of ODC mRNA was noticeable after about 3 hours of treatment, reaching near maximum inhibition by 12 hours. Further analysis revealed that a 24-hour exposure to 0.5 μM all-trans-retinoic acid not only decreased ODC mRNA levels but also reduced ODC enzyme activity significantly.

This preliminary study aims to evaluate the plasma and skin concentrations of Ro 15-0778 and its phenolic metabolite Ro 14-6113 in hairless rats administered an oral dose of 10 mg/kg Temarotene daily for 10 days. By collecting blood (2-3 mL) and skin (200-300 mg) samples at intervals from 0.5 to 240 hours post the final dose, the study utilizes a sensitive HPLC method for the concurrent analysis of both compounds, achieving detection limits of 2 ng/mL in plasma and 10 ng/g in total skin (epidermis and dermis). Results indicate that, after 10 hours, plasma levels of Ro 14-6113 were found to be 5-13 times greater than those of Ro 15-0778, and 4-10 times higher in skin within the initial 48 hours. Notably, the skin concentrations of both compounds exceeded their respective plasma levels.