Topical therapies for rheumatoid arthritis by gel ointments containing indomethacin nanoparticles in adjuvant-induced arthritis rat.

Indomethacin (IMC), a nonsteroidal anti-inflammatory drug, has been used in the treatment of rheumatoid arthritis (RA), although its clinical use has been limited by its systemic side effects that include gastrointestinal lesions. Therefore, the development of IMC formulations that do not cause gastrointestinal lesions is highly anticipated. In this study, we designed new topical formulations containing IMC solid nanoparticles (IMCnano gel ointment), and investigated their pharmacokinetics. In addition, we demonstrate the preventive effects of this topical application of IMC nanoparticles on inflammation in adjuvant-induced arthritis rat (AA rat). The IMCnano gel ointment was prepared using Bead Smash 12 (a bead mill) and additives including 2-hydroxypropyl-β-cyclodextrin, methylcellulose and Carbopol 934; the mean particle size of the IMC nanoparticles was 173 ± 91 nm (means ± S.D.). The application of the IMCnano gel ointment attenuated the increase in paw edema of the hind feet of AA rats in comparison with AA rats treated with gel ointment containing IMC microparticles (IMCmicro gel ointment, particle diameter 17.1 ± 11.6 mm, means ± S.D). In addition, the accumulation of IMC from the IMCnano gel ointment in skin tissue was significantly large than for the IMCmicro gel ointment; however, the plasma IMC concentrations were similar for the IMCmicro and IMCnano gel ointments. Our findings suggest that the dermal application of nanoparticles may enable a medication to be applied without high-systemic drug levels, which could provide efficient and effective therapy that spares patients from unwanted side effects. A formulation of a topical drug delivery system using IMC nanoparticles may provide a delivery option for the clinical treatment of RA.