Multi-component microneedle drug delivery system of sanfu herbal patch for allergic asthma in rats

A dissolvable microneedle system (SFP-MNs) loaded with seven principal Sanfu Herbal Patch components was developed to assess transdermal delivery feasibility and therapeutic efficacy in a rat model of allergic asthma. SFP-MNs were fabricated using a two-step centrifugation-assisted template molding method and characterized in terms of morphology, mechanical strength, skin penetration capability, and in vitro drug release behavior. An ovalbumin (OVA)-induced allergic asthma model was established in Sprague-Dawley (SD) rats to investigate the in vivo performance of the microneedles. Pulmonary interstitial fluid was continuously sampled by microdialysis following transdermal administration, and drug concentrations were quantified using UPLC-MS/MS. Pharmacodynamic responses were evaluated by measuring histamine (HIS), immunoglobulin E (IgE), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) levels using ELISA, together with histopathological examination by hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) staining. A pharmacokinetic-pharmacodynamic (PK-PD) model was subsequently established to characterize the relationship between drug exposure and therapeutic response. The prepared SFP-MNs exhibited excellent mechanical properties, efficient skin penetration, and sustained drug release. In vivo, SFP-MNs achieved effective transdermal delivery of the encapsulated components and produced superior therapeutic outcomes compared with an equivalent-dose conventional Sanfu Herbal Patch gel. Specifically, high-dose SFP-MNs markedly alleviated airway inflammation, reduced inflammatory biomarker levels, and attenuated pulmonary histopathological injury in allergic asthmatic rats. These findings demonstrate that SFP-MNs represent a promising transdermal drug delivery platform with the potential to replace conventional Sanfu Herbal Patch for the treatment of allergic asthma while providing sustained drug release and improved therapeutic efficacy.