Selection of a water-containing composition for 5-amino-4-(3-aminophenyl)-N-(tert-butyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxamide (TP03), a luteinizing hormone receptor agonist: steroidogenic activity and bioavailability in male rats

One of the areas of research in the search for effective stimulators of ovarian and testicular steroidogenesis is the development of low-molecular-weight allosteric agonists of the luteinizing hormone (LH) receptor, which offer several advantages over gonadotropins used in medicine. We previously developed 5-amino-4-(3-aminophenyl)-N-(tert-butyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxamide (TP03), a steroidogenesis and ovulation stimulator. However, TP03, being a highly hydrophobic compound, is insoluble in water and is used as a solution in DMSO, which limits its practical applications. The aim of the study was to find the optimal water-containing composition for TP03, study the ability of TP03 in this composition to stimulate testosterone production and evaluate its bioavailability for the testes. Among the studied compositions, #2 – Solutol-HS15/PEG400/water 3:2:5, and #3 - DMSO/PEG400/Tween80/phosphate buffer 1:6:1:12 were suitable for TP03. In Composition #2, TP03, when administered orally (1.5, 3 and 5 mg/kg) and intraperitoneally (15 mg/kg) to male rats, stimulated testosterone production, and the hormone level in both cases increased after 30 minutes, which was not observed when TP03 was administered in DMSO. In Composition #3, TP03 (i.p., 15 mg/kg) resulted in a gradual increase in testosterone levels, reaching a maximum after 3 hours. This effect was superior to that observed with the DMSO solution. In Compositions #2 and #3, TP03 content in the blood and testes 3 hours after oral and intraperitoneal administration exceeded those observed with the DMSO solution, indicating higher bioavailability of TP03. Thus, optimal solubilization conditions for TP03 have been selected, which is important for the development of TP03-based drugs.

The work was supported by the state assignment of the Institute of Evolutionary Physics and Biochemistry of the Russian Academy of Sciences (No. 075-00264-26-00).