Yau WP et al. (2007) Is a standard fixed dose of mycophenolate mofetil ideal for all patients? Nephrol Dial Transplant [doi:10.1093/ndt/gfm468]

The efficacy and toxicity of mycophenolate mofetil (MMF) are concentration-dependent, yet a standard fixed dose of 2 g/day is currently recommended for maintenance immunosuppression in adult renal transplant recipients also receiving ciclosporin and corticosteroids. Studies of Asian patients have indicated that MMF doses below 2 g/day can be effective, possibly because of the typically lower total body weight of Asian populations relative to those from Europe or North America.

Yau et al. examined the steady-state pharmacokinetics of mycophenolic acid (MPA), the active metabolite of MMF, in 53 Asian adult renal transplant recipients. Median total body weight was 66.8 kg (range 33.1–108.1 kg). Patients had received MMF (0.5–2.0 g/day; 86.8% were receiving a dose <2.0 g/day), ciclosporin and prednisolone for at least 3 months before recruitment. Exposure to MPA correlated significantly with body-weight-adjusted MMF dose (r2 = 0.49, P <0.0005; after omission of outliers). Regression analysis revealed that therapeutic levels of MPA exposure (area under the plasma-concentration–time curve at steady state of 30–60 mg·h/l) could be achieved by a twice daily dose of MMF at 5–17 mg/kg. Most patients had MPA exposure within the therapeutic range, despite receiving MMF doses of <2 g/day.

The authors suggest that an MMF dose of 12 mg/kg twice daily could be used to target the middle of the therapeutic range in Asian renal transplant recipients, and potentially in other ethnic groups. Considerable interindividual variability in pharmacokinetics was observed, however, even after adjustment for body weight, indicating that dose adjustment of MMF on the basis of therapeutic drug monitoring of MPA would be required.