Bilayer dissolving microneedle array containing 5-fluorouracil and triamcinolone with biphasic release profile for hypertrophic scar therapy

Hypertrophic scar(HS)is an undesirable skin abnormality following deep burns or operations.Although intralesional multi-injection with the suspension of triamcinolone acetonide(TA)and 5-fluorouracil(5-Fu)has exhibited great promise to HS treatment in clinical,the difference of metabolic behavior between TA and 5-Fu remarkably compromised the treatment efficacy.Besides,the traditional injection with great pain is highly dependent on the skill of the experts,which results in poor compliance.Herein,a bilayer dissolving microneedle(BMN)containing TA and 5-Fu(TA-5-Fu-BMN)with biphasic release profile was designed for HS therapy.Equipped with several micro-scale needle tips,the BMN could be self-pressed into the HS with uniform drug distribution and less pain.Both in vitro permeation and in vivo HS retention tests revealed that TA and 5-Fu could coexist in the scar tissue for a sufficient time period due to the well-designed biphasic release property.Subsequently,the rabbit ear HS model was established to assess therapeutic efficacy.The histological analysis showed that TA-5-Fu-BMN could significantly reduce abnormal fibroblast proliferation and collagen fiber deposition.It was also found that the value of scar elevation index was ameliorated to a basal level,together with the downregulation of mRNA and protein expression of Collagen I(Col I)and transforming growth factor-β1(TGF-β1)after application of TA-5-Fu-BMN.In conclusion,the BMN with biphasic release profiles could serve as a potential strategy for HS treatment providing both convenient administrations as well as controlled drug release behavior.