FORMULATION AND EVALUATION OF TACROLIMUS LOADED TRANSFERSOMAL SUBLINGUAL FILMS FOR EFFICIENT MANAGEMENT OF ORGAN REJECTION: IN VITRO AND IN VIVO STUDY
Authors: R. SUMA , V. KARWA PREETI , DEVI V. KUSUM 
Published: November 2023

Objective: Patients travailing with end-stage organ failure can benefit from a life-saving treatment protocol called organ transplantation that also rallies eminence of life. Tacrolimus plays an important role in maintaining the healthy status of the organ transplanted, but its widespread clinical application is constrained due to low oral bioavailability which can be the limiting factor for the reduction in life span of transplanted healthy organ.
Methods: To overcome the drawbacks of tacrolimus and to maximize its therapeutic efficiency, tacrolimus was formulated as transfersomes using thin film hydration method using soyalecithin and Tween-80, optimized by Central composite designs and characterized for Particle size, deformability index (DI), entrapment efficiency(EE%) and Zeta potential. The selected transfersome formulation was incorporated into sublingual films using Hydroxy Propyl Methyl Cellulose (HPMC) as a film-forming polymer and Polyethylene Glycol (PEG-400) as Plasticizer. The physical characteristics (average weight, pH, uniformity of weight and thickness) of the prepared films were studied, in addition they were evaluated for the in vitro drug release, ex vivo permeation, Differential Scanning Calorimetry (DSC), Attenuated Reflectance Spectroscopy (ATR), Scanning Electronic Microscopy (SEM), stability and in vivo pharmacokinetics in rats to prove the effect of flexibility provided by vesicle formation through sublingual route for enhanced systemic availability of tacrolimus.
Results: Designed and optimized transfersomal vesicles showed the vesicle size of 139±2.1 nm with a Deformability Index of 8.53±1.9%, Entrapment Efficiency of 86.66±1.2% and zeta potential of-23.6 mV respectively. Optimized Tacrolimus-loaded transfersomal vesicles (TAC-TFs) showed controlled release with more than 80±3.4% for an extended period of time compared to pure drug Tacrolimus. The average weight of all prepared transfersomal sublingual film (TAC_TF_SL films), batches were found in the range of 55.8±1.45 to 94.2±1.42 mg with mean thickness in the range of 0.23+0.1 to 0.52±0.2 mm indicating uniform cast of respective batches. The surface pH was found to be in the range of 6.9 to 7.0 which was close to saliva pH.
Optimized transfersomal sublingual films as well as nanovesicular dispersions found to be followed Zero order diffusion coupled with polymer relaxation. Ex vivo studies revealed the improved permeation of 6.51±0.04µg drug through sublingual mucosa than pure drug of 1.2±0.01 µg, depicting the significant role of soyalecithin and edge activator in the formulations. Transfersomal sublingual films exhibited controlled release with higher plasma concentration of 9.16±2.34 µg/ml at Tmax of 1.29±1.51h in comparison with 7.99±1.23 µg/ml at Tmax of 0.75±1.78h (oral marketed dosage form Pengraf capsules) embarking the higher rate of controlled absorption after sublingual delivery of optimized sublingual films with significant increase in AUC of 129.87±2.40 μg/ml/h when compared to AUC of marketed dosage form of 69.19±1.46 μg/ml/h. In addition, the absolute bioavailability of the drug following sublingual administration was found to be 70.77±2.92% in comparison with that after oral administration 40.60±2.34%.
Conclusion: Designed Tacrolimus loaded transfersomal sublingual films can be a promising carrier for delivering tacrolimus through sublingual route by enhancing drug bioavailability efficiently, which can be a boon to organ-transplanted patients.