diphenylhexatriene and Lipidoses

An in vitro method to predict phospholipidosis-inducing potential of cationic amphiphilic drugs (CADs) was developed using biochemical and physicochemical assays. The following parameters were applied to principal component analysis, as well as physicochemical parameters: pK(a) and clogP; dissociation constant of CADs from phospholipid, inhibition of enzymatic phospholipid degradation, and metabolic stability of CADs. In the score plot, phospholipidosis-inducing drugs (amiodarone, propranolol, imipramine, chloroquine) were plotted locally forming the subspace for positive CADs; while non-inducing drugs (chlorpromazine, chloramphenicol, disopyramide, lidocaine) were placed scattering out of the subspace, allowing a clear discrimination between both classes of CADs. CADs that often produce false results by conventional physicochemical or cell-based assay methods were accurately determined by our method. Basic and lipophilic disopyramide could be accurately predicted as a nonphospholipidogenic drug. Moreover, chlorpromazine, which is often falsely predicted as a phospholipidosis-inducing drug by in vitro methods, could be accurately determined. Because this method uses the pharmacokinetic parameters pK(a), clogP, and metabolic stability, which are usually obtained in the early stages of drug development, the method newly requires only the two parameters, binding to phospholipid, and inhibition of lipid degradation enzyme. Therefore, this method provides a cost-effective approach to predict phospholipidosis-inducing potential of a drug.

Topics: Cations; Diphenylhexatriene; Drug-Related Side Effects and Adverse Reactions; Fluorescent Dyes; Humans; Lipidoses; Microsomes; Multivariate Analysis; Phospholipase A2 Inhibitors; Principal Component Analysis; Protein Binding

Binding characteristics of nine amphiphilic drugs, which induce pulmonary phospholipidosis, to L-alpha-dipalmitoyl phosphatidylcholine (DPPC) vesicles were studied using fluorescence probes, 1,6-diphenyl-1,3,5-hexatriene and 1-anilino-8-naphthalene sulfonate (ANS) for hydrophobic and hydrophilic interactions, respectively. Drug binding to DPPC was quantitated using Scatchard analysis. The tested drugs bound to DPPC with different capacities. The order of binding capacity to hydrophobic site of DPPC using 1,6-diphenyl-1,3,5-hexatriene as fluorescence probe was promethazine greater than amiodarone greater than chlorpromazine greater than chloramphenicol greater than imipramine greater than trimipramine greater than propranolol much greater than chloroquine and chlorphentermine. Two binding affinities were evident for amiodarone, chlorpromazine, imipramine, trimipramine and promethazine. The order of binding strength at high affinity site was amiodarone greater than trimipramine greater than chlorpromazine greater than promethazine greater than imipramine. The order of drug binding capacity using ANS as fluorescence probe was chlorphentermine greater than trimipramine greater than propranolol much greater than amiodarone, chloroquine and chloramphenicol. Each of these drugs displayed a single binding affinity. Imipramine and chlorpromazine at 1 mM and higher concentrations showed intense fluorescence with ANS (5-20 microM) in the absence of DPPC indicating an interaction of these drugs with ANS. Chloroquine did not bind to either sites on DPPC. The binding of these drugs and their interactions with hydrophobic or hydrophilic sites of DPPC were correlated with their capacity to induce pulmonary phospholipidosis. These results indicate that not all the drugs which bind to DPPC in vitro induce phospholipidosis in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amiodarone; Anilino Naphthalenesulfonates; Binding Sites; Chloramphenicol; Chloroquine; Chlorpromazine; Diphenylhexatriene; Imipramine; Lipidoses; Lung Diseases; Membrane Lipids; Phospholipids; Promethazine; Propranolol; Surface-Active Agents; Trimipramine