Astellas Pharma US, Inc., a subsidiary of Astellas Pharma Inc. has submitted to the US FDA an NDA for the immunosuppressant FK506 modified release formulation (tacrolimus) with the target indication of the prevention of organ rejection in patients receiving organ transplants.

According to a company release, tacrolimus is an immunosuppressant invented by Astellas. It is marketed as an agent to suppress rejection after organ transplantations under the brand name of Prograf in over 70 countries in the world.

The FK506 modified release formulation is a modified release version of Prograf that can be administered once a day. Patients' compliance is thus expected to be improved compared to twice a day with the conventional formulation. The FK506 modified release formulation is therefore expected long term graft protective effect. In addition, this formulation is expected to be at least as safe as the conventional formulation since the peak blood concentration can be controlled at lower levels. It also makes it possible to optimise the dosage based on blood concentrations.

At present, application for regulatory approval is being prepared in Europe, while phase II trials are underway in Japan.