Co-Delivery of Teriflunomide and Methotrexate from Hydroxyapatite Nanoparticles for the Treatment of Rheumatoid Arthritis: In Vitro Characterization, Pharmacodynamic and Biochemical Investigations.

Purpose: The present investigation was aimed at developing Teriflunomide (TEF) and Methotrexate (MTX) loaded hydroxyapatite nanoparticles and increasing tolerability towards combination therapy against rheumatoid arthritis by reducing hepatotoxicity.

Methods: Drug-loaded HAp-NPs were synthesized by wet-chemical precipitation method and optimized by Box-Behnken experimental design. The developed NPs were subjected to in vitro and in vivo characterization. In-vivo pharmacodynamics and biochemical studies were performed on adjuvant- induced arthritis model treated with different formulations; MTX-TEF-SOL, TEF-HAp-NP, MTX-HAp-NP, TEF-MTX-HAp-NP, FOLITRAX-10 and AUBAGIO.

Results: The size of the optimized formulations, TEF-HAp-NP and MTX-HAp-NP, was found to be 224.3 ± 83.80 nm and 268.3 ± 73.86 nm with drug loading 53.11 ± 0.84% and 67.04 ± 1.12% respectively. In vitro release of TEF from TEF-HAp-NP (70.41 ± 1.22%) and MTX from MTX-HAp-NP (82.43 ± 1.31%) up to 24 h revealed sustained release pattern. Results of the arthritic assessment study showed a significant (P < 0.05) reduction in ankle diameter (61.30 ± 7.42) and arthritis score (2.35 ± 0.24) with a marked restoration of ankle joint micro-architecture in TEF-MTX-HAp-NP treated group. During Hepatotoxicity studies, liver histopathology revealed that the formulation MTX-TEF-HAp-NP was least hepatotoxic with less hepatocyte swelling and fibrous connective tissue proliferation while Folitrax-10 was found to be most hepatotoxic. Biochemical studies revealed that Folitrax-10 significantly (P < 0.05) increased the GOT (313.64 ± 16) and GPT level (334.46 ± 13) while insignificant (P > 0.05) change in GOT (263.68 ± 17) and GPT (229.38 ± 10) level was recorded with TEF-MTX-HAp-NP.

Conclusions: We report that the subcutaneous delivery of TEF-MTX-HAp-NP was most effective as it successfully reduced the dosage by half for maximizing therapeutic efficacy and minimizing side effects. Graphical Abstract ᅟ.