Development Of Tacrolimus Ointment And Research On Quality Standards

Macrolide antibiotics have been widely used in clinic for many years. In1984, Fujisawa Pharmaceutical Co.,Ltd. separated macrolide immunosuppressant FK506whose relative molecular weight was822×103from the fermentation broth of streptomyces tsukubaensis, and named it as tacrolimus. It was first reported in1987that tacrolimus has significant immunosuppressive activity on T lymphocytes. In1989, tacrolimus, whose immunosuppressive action was50-100times stronger than cyclosporine, was first used in the transplantation of liver, kidney and pancreas, then in heart and lung. In1992, Mrowietz first reported that systematic application of macrolide immunosuppressant could be used in the treatment of skin diseases, which meant that oral tacrolimus could make skin lesions disappeared rapidly. Compared to cyclosporine, tacrolimus has a smaller molecular weight, better penetration of the skin, which makes the external application of tacrolimus effective to allergic contact eczema. In1994, Nakogawa first used0.03%、0.1%and0.3%tacrolimus to conduct a open-label study in treatment of atopic dermatitis with or without moss. The result showed that the effective rate was38.2%and48.5%respectively, and about one-third of patients had local irritation but no need of drug withdrawal. In December2000, tacrolimus was approved in the treatment of moderate to severe atopic dermatitis in the United States, which made it the first non-corticosteroid topical immune modulators to atopic dermatitis after corticosteroids over fifty years.Tacrolimus has many applications in the treatment of dermatology. It includes systematic treatment and topical treatment. However, as the systemic treatment of tacrolimus has side effects, the promotion of its topical preparations is getting popular. The local treatment of tacrolimus is suitable for eczema, atopic dermatitis, lichen planus, rosacea caused by corticosteroids, psoriasis, vitiligo, alopecia areata, pyoderma gangrenosum, chronic cutaneous graft-versus-host disease, ichthyosis, sarcoidosis and so on.The main target of tacrolimus is lymphocytes. It can inhibit the activity of T cell by inhibiting the gene expression of early stage lymphocytes. Penetrating the cell membrane, tacrolimus combines with intracellular receptor FKBP and form a FKBP-12compound which selectively act on calcium ion-dependent signal transduction pathway to inactivate the calcineurin, thus inhibit gene transcription of cytokines relied on nuclear factor of activated T cells(NF-AT). In addition, tacrolimus can also inhibit the generation of5-HT and leukotriene.In this article, we make up a external preparation of the model drug tacrolimus and conducted various pharmaceutical research. Firstly, we studied the formulation and preparation process research of tacrolimus ointment to select suitable lubricant, ointment base, thickener, hardener and solvent and filtered the amount of various excipients. The optimum prescription was determined by evaluating appearance, viscosity, penetration.Secondly, we conducted the quality standard research of tacrolimus ointment according to the relevant quality requirements. The main indexes were character, identification, packing volumes, uniformity, related substances, content and so on. We determined the content and related substances of tacrolimus ointment by HPLC and validated the methodology of determining content and related substances. Asscessing the above indicators comprehensively, we established a systematic testing standards to control the quality of the final products.Thirdly, we studied the stability study of tacrolimus ointment, including test of influence factors (temperature, humidity and illumination), stability tests of6months’ accelerating experiment and12months’ long-term studies. Accordingly, we decided the storage condition of tacrolimus ointment as room temperature25℃, temperature range is15～30℃. Tacrolimus ointment can remain stable in24months at room temperature.Finally, we studied the vitro transdermal absorption experiment of tacrolimus ointment and validated the methodology. Results showed that the cumulative transdermal amount of main drug had good linear relationship with the penetration time, and its in vitro transdermal effect is perfect.