Estimation of drug absorption rates using a deconvolution method with nonequal sampling times

Abstract

A method affording direct estimation of the drug absorption rate from blood level data using arbitrary time intervals has been derived based on the staircase input principle. In the derivation, the drug was assumed to follow linear kinetics where the plasma concentration of the drug after an impulse input is expressed by a multiexponential function. Drug absorption was assumed to occur at a constant rate during each subsequent sampling interval. The absorption rate profiles obtained by the method using several numerical examples were expressed as a set of rectangular pulses. Divergence in the profiles reflected blood sampling measurement errors rather than errors due to the deconvolution. Smoothing of the rate profiles by calculating the mean of the absorption rates between adjacent time intervals gave realistic results. Absorption rate profiles for theophylline obtained by the method using published data gave information on the initiation and termination of the absorption as well as the extent of absorption from the dosage form.

Stability of finite difference deconvolution I: theoretical analysis

“…To simplify the analysis, C l (t) has been treated as error-free in a number of previous numerical simulation studies of deconvolution in pharmacokinetics [10,11,13,16,22,23]. The corresponding assumption in the present case is that the matrices (7), (7%), (13) and (13%) are approximately error-free.…”

Improvement of the Solubility and Intestinal Absorption of Curcumin by <i>N</i>-Acyl Taurates and Elucidation of the Absorption-Enhancing Mechanisms

“…Furthermore, we calculated the bioavailability and absorption rate of CUR by a deconvolution method. 29) In the presence of CMT, LMT, MMT, and SMT, the bioavailability % of CUR at 240 min after administration were 17.7, 18.9, 17.7, and 9.2%, respectively. Therefore, the bioavailability % of CUR is similar among CMT, LMT, and MMT groups, which is 2-fold higher than that in SMT group.…”

The reproducibility of quinine bioavailability.

“…The absorption of quinine from the oral dosage form was estimated by numerical deconvolution (Iga et al, 1986) and the results were expressed as cumulative fraction absorbed with time. Because of the very rapid distribution phase plasma drug concentrations following infusion were described by a monoexponential function.…”