Co-delivery of drugs by adhesive transdermal patches equipped with dissolving microneedles for the treatment of rheumatoid arthritis

In this study, a dosage form consisting of dissolving (D) microneedles (M) and an adhesive (A) transdermal patch (P; DMAP) was designed and pre-clinically evaluated for the treatment of rheumatoid arthritis (RA). The tip of the dissolving microneedles (DMNs) was loaded with the macromolecular drug melittin (Mel@DMNs), this to treat joint inflammation and bone damage, while the adhesive transdermal patches contained the low molecular weight drug diclofenac sodium (DS; DS@AP) for pain relief. Mel@DMNs and DS@AP were ingeniously connected through an isolation layer for compounding Mel-DS@DMAP for the simultaneous delivery of the drugs. In vitro and in vivo experiments showed that DS@AP did not affect the mechanical properties and dissolution process of Mel@DMNs while the pores formed by the microneedles promoted the skin penetration of DS. Treatment of rats suffering from RA with Mel-DS@DMAP reduced paw swelling and damage of the synovium, joint and cartilage, suggesting that the 'patch-microneedle' dosage form might be promising for the treatment and management of RA.