Pharmacokinetic and pharmacodynamic model for analysis of adalimumab administered for Crohn's disease.

Adalimumab (ADA) is used as a therapeutic agent for Crohn's disease (CD). Although the dosage regimen has been established through clinical trial experience, it has not been analysed theoretically. The present study analysed of sequential changes in the Crohn's disease activity index (CDAI) after repeated administrations of adalimumab using a pharmacokinetic and pharmacodynamic model. In addition, we analysed the validity of the dosage regimen, and the potential efficacy gained by increasing the dose and reducing the interval of administration. The sequential changes in CDAI values obtained with our model were in good agreement with observed CDAI values, which is considered to show the validity of our analysis. We consider that our results showed the importance of a loading dose of adalimumab to obtain remission in an early stage of active CD. In addition, we showed that patients who have an incomplete response to adalimumab can obtain similar efficacy from increasing the dose and reducing the dose interval. In conclusion, our results showed that the present model may be applied to predict the CDAI values of adalimumab for CD. They indicate the validity of the dosage regimen, as well as the efficacy of increasing the dose and reducing the dose interval.