Clinical observations suggested that dose requirements for some immunosuppressive drugs might be different towards the lower side in some eastern populations.
50 out 162 patients were converted from cyclosporine-based immunosuppression to tacrolimus. Reasons for conversion were acute rejection in 23 patients, hirsutism and gingival hypertrophy in 12 patients, chronic allograft nephropathy in 4 patients, Hypertension in 3 patients and other reasons in 8 patients. Target levels were 10-15ng/ml for patients with acute rejection and 5-8ng/ml for patients after the first year of transplantation.
44 patients had 180 blood levels of tacrolimus. The method and reagents used was IMX- Abbot. Blood specimen was collected on an EDTA tube. The mean daily dose of Tacrolimus used was 4.89±2.56 mg to achieve a mean blood level of 11.31±5.22ng/ml. The mean weight was 64.5kg. This gives us an average dose of 0.075 mg/Kg to achieve the above-mentioned level. This is lower than the official 0.15 mg/kg recommended dose to achieve 5-8ng/ml levels. The reasons for this observation was not studied but could be due to dietary factors influencing the absorption and or some enzymatic subtypes of the Cytochrome P450 systems.
This study suggests that ethnic factors should be taken into consideration when using some immunosuppressive drugs.