Editor, – I refer to the comment on tacrolimus published recently in your 'New drugs' section (Aust Prescr 1998;21:81-2).
The study referred to was published in 1994 as the preliminary experience of 8 respected European centres.
Follow-up data from the same trial has been subsequently published.1 This latter report describes a similar safety profile of tacrolimus compared with cyclosporin, but with a less problematic convalescence. It is stressed that careful attention to dosing and blood level assessment is necessary. Concentrations of both tacrolimus and cyclosporin require routine post-transplant monitoring, both are metabolised by cytochrome P450 and both have similar drug interactions. Toxicity of both agents is largely dose related. In the earlier study, blood levels of tacrolimus were not available at the time of dose adjustments and the doses initially recommended were inappropriately high. Continuous infusion of tacrolimus was used initially and this practice has now been abandoned by most programs because of the recognised greater toxicity of the parenterally administered drug.
The comparison between cyclosporin and tacrolimus has less relevance in 1998 as the former has been largely replaced with the microemulsified version of cyclosporin. This new formulation and tacrolimus are both well absorbed from the gut immediately after transplantation.
Stephen V. Lynch
Associate Professor of Surgery
Deputy Director
Queensland Liver Transplant Service
Royal Children's Hospital
Herston, Qld
Editor's note:
The Pharmaceutical Benefits Pricing Authority's Therapeutic Relativity Sheets (August 1998) state 'Tacrolimus was accepted as being more effective than cyclosporin and less costly'.
