A LIMITED SAMPLING METHOD FOR THE ESTIMATION OF FLUNARIZINE AREA UNDER THE CURVE (AUC) AND MAXIMUM PLASMA CONCENTRATION (CMAX)

A limited sampling model has been developed for flunarizine following a 30 mg oral dose in epileptic patients who were receiving phenytoin or carbamazepine or both, to estimate the area under the curve (AUC) and maximum plasma concentration (C_max). The model was developed using training data sets from 30, 20, 15, or 10 patients at one or two time points. The equations describing the models for AUC using two time points (3 and 24 h) and C_max for the training data set of 30 subjects were AUC_predicted=11·1 C_{3 h}+121·4 C_{24 h}–157 (r =0·80) C_{max(predicted)}=0·036 AUC+42·9 (r =0·74) The model was validated on 64 patients who received flunarizine orally. The model provided reasonably good estimates for both AUC and C_max. The mean predicted AUC of flunarizine was 1230±717 ng h mL⁻¹, whereas the observed AUC was 1203±900 ng h mL⁻¹. The bias of the prediction was 2% and precision was 28%. The mean predicted C_max of flunarizine was 86±32 ng mL⁻¹ as compared to an observed mean C_max of 90±42 ng mL⁻¹. The bias and precision of the prediction were 4% and 24%, respectively. The method described here may be used to estimate AUC and C_max for flunarizine without detailed pharmacokinetic studies. © 1997 by John Wiley & Sons, Ltd.