Kiyohiko Sugano

High Throughput Prediction of Oral Absorption: Improvement of the Composition of the Lipid Solution Used in Parallel Artificial Membrane Permeation Assay

The purpose of the present study was to improve the composition of the lipid solution used in parallel artificial membrane permeation assay for the precise prediction of oral absorption. We modified the composition of lipid solution, which was used to make a lipid membrane on the filter support. First, we changed the chain length of organic solvent (PC/alkyldienes [C7-C10]). A negative charge was then added to the membrane to mimic the intestinal membrane (PC/stearic acid/1,7-octadiene and PC/PE/PS/PI/cholesterol/1,7-octadiene). Finally, we examined the predictability of the PC/PE/PS/PI/CHO/1,7-octadiene membrane using structurally diverse compounds. Permeability coefficients of tested compounds were increased as the chain length of alkyldiene became shorter. The addition of a negative charge to the membrane increased the permeability of the basic compounds. However, the negatively charged membrane with stearic acid showed different permeability profiles from PC/PE/PSIPI/CHO. The predictability of the PC/PE/PS/PI/CHO/1,7-octadiene membrane was adequate (r = 0.858, n = 31) for use during the early stages of the drug discovery/development process.

Optimized conditions of bio-mimetic artificial membrane permeation assay.

Effects of pH and co-solvents on the bio-mimetic artificial membrane permeation assay were investigated to determine the optimal conditions for the prediction of oral absorption. The permeability (P(am)) of 33 structurally diverse drugs to the PC/PE/PS/PI/CHO/1,7-octadiene membrane system (bio-mimetic lipid (BML) membrane) was measured at pH 5.5, 6.5, and 7.4. The pH dependence of P(am) was in accordance with the pH partition theory. The better prediction of oral absorption (fraction of a dose absorbed) was shown under the pH 5.5 condition (r=0.866, n=25) and/or pH 6.5 (r=0.865, n=28), rather than pH 7.4 (r=0.767, n=24). Then, the appropriate conditions for determining the permeability of poorly soluble compounds were examined. Dimethysulfoxide (DMSO), ethanol (EtOH) and polyoxyethyleneglycol 400 (PEG 400) were added up to 30% to the transport medium as solubilizers. DMSO, EtOH and PEG 400 decreased P(am) of hydrocortisone and propranolol. For example, DMSO (30%) decreased P(am) of hydrocortisone by 60% and by 70% in the case of propranolol. DMSO and PEG 400 also decreased P(am) of ketoprofen. In contrast, EtOH produced an opposite effect on permeability, i.e. an increased P(am) of ketoprofen. Therefore, the high concentration of these co-solvents could lead to the under- or overestimation of drug permeability.

Prediction of passive intestinal absorption using bio-mimetic artificial membrane permeation assay and the paracellular pathway model

The purpose of this study was to construct and examine the prediction model for total passive permeation through the intestinal membrane. The paracellular pathway prediction model based on Renkin function (PP-RF) was combined with a bio-mimetic artificial membrane permeation assay (BAMPA), which is an in vitro method to predict transcellular pathway permeation, to construct the prediction model (BAMPA-PP-RF model). The parameters of the BAMPA-PP-RF model, e.g. apparent pore radius and potential drop of the paracellular pathway, were calculated from BAMPA permeability, the dissociation constant, the molecular radius and the fraction of a dose absorbed in humans consisting of 80 structurally diverse compounds. The apparent pore radius and the apparent potential drop obtained in this study were 5.61-5.65 A and 75-86 mV, respectively, and these were in accordance with the previously reported values. The mean square root error of the BAMPA-PP-RF model was 13-14%. The BAMPA-PP-RF model was shown to be able to predict the total passive permeability more adequately than BAMPA alone.

Prediction of human intestinal permeability using artificial membrane permeability

The purpose of the present study was to examine a correlation between the human intestinal permeability (P(eff)) and the bio-mimetic artificial membrane permeability corrected by the paracellular pathway model based on the Renkin function (P(PAMPA-PP-RF)) and to construct a prediction scheme. The effect of the unstirred water layer was incorporated to the prediction scheme. Eighteen P(eff) values of passively absorbed drugs were employed for the analysis. The correlation coefficient (CC) between the predicted and observed logP(eff) was 0.91. P(eff) of furosemide, hydrochlorothiazide and creatinine were underestimated by P(PAMPA-PP-RF). When these compounds were excluded, CC was 0.97. Without the correction for the paracellular pathway, P(eff) of small, cationic and hydrophilic compounds were underestimated. Therefore, P(PAMPA-PP-RF) was found to be an adequate in vitro surrogate for P(eff).

Correction of Permeability with Pore Radius of Tight Junctions in Caco-2 Monolayers Improves the Prediction of the Dose Fraction of Hydrophilic Drugs Absorbed by Humans

AbstractPurpose. To improve predictions of fraction dose absorbed (Fa) for hydrophilic drugs, a correction of paracellular permeability using the pore radius of tight junctions (TJs) in Caco-2 monolayers was performed. Methods. The apparent permeability coefficient (Papp) of drugs was measured using the Caco-2 assay and the parallel artificial membrane permeation assay (PAMPA), and values were corrected with the pore radius of TJs. Results. An equation for calculating the pore radius of TJs from the Papp of lucifer yellow was obtained. The optimal pore radius of TJs in Caco-2 monolayers for predicting human Fa was calculated to be 7 Å. The correlation between the actual and predicted Fa was improved by using the Papp corrected with the pore radius of TJs. Permeability in the PAMPA, which was corrected using the pore radius and membrane potential, was well correlated with that in the Caco-2 assay. Most of the hydrophilic drugs tested in this study were absorbed mainly through the paracellular pathway. Conclusions. The results suggest the necessity of optimizing paracellular permeation for the prediction of Fa, and also the importance of the paracellular pathway to the absorption of hydrophilic drugs. This method might contribute to the setting of appropriate dosages and the development of hydrophilic drugs.

Biopharmaceutics classification by high throughput solubility assay and PAMPA.

The purpose of the present study was to examine the relevancy of the high throughput solubility assay and permeability assay to the biopharmaceutics classification system (BCS). Solubility and permeability were measured by high throughput solubility assay (HTSA) and parallel artificial membrane permeation assay (PAMPA), respectively. High throughput solubility assay was performed using simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid without bile acid (SIF, pH 6.8). We categorize 18 drugs based on the BCS using HTSA and PAMPA. Fourteen out of 18 drugs were correctly classified (78% success rate). The result of the present study showed that HTSA could predict BCS class with a high success rate, and PAMPA could also be useful to predict the permeation of drugs.

Quantitative structure-intestinal permeability relationship of benzamidine analogue thrombin inhibitor.

The intestinal permeability of benzamidine analogue thrombin inhibitor is correlated with molecular volume, lipophilicity (calculated log P and IAM column capacity factor), hydrogen bond acidity/basicity and dipolarity.