title: Drug interaction studies between paclitaxel (Taxol) and OC144-093--a new modulator of MDR in cancer chemotherapy.
abstract: The MDR modulator, OC144-093, is a potential candidate for use in cancer therapy and exhibits potent biological activity in vitro and in vivo when combined with anticancer agents such as paclitaxel. Its inhibitory interaction with P-glycoprotein (Pgp), the mdr1 gene product and a mechanistic participant in multidrug resistance, underlies its activity as a modulator of MDR. Having previously shown that OC144-093 is not a substrate for CYP3A we first examined the effects of OC144-093 on paclitaxel metabolism in vitro. Using human liver microsomes, we have demonstrated that OC144-093 inhibited the CYP3A mediated metabolism of paclitaxel at high concentrations only (Ki = 39.8 +/- 5.1 microM, n=3). Pharmacokinetic results also show that an oral dose of OC144-093, co-administered with paclitaxel caused negligible disturbance of the pharmacokinetic profile for paclitaxel when injected intravenously. In contrast, AUC values were elevated approximately 1.5-fold in all groups treated orally with paclitaxel and OC144-093. Cmax was enhanced approximately 2-fold in the co-dosed group. These characteristics are consistent with Pgp blockade in the gut enhancing oral bioavailability. Elimination properties of paclitaxel were affected only upon multiple dosing of OC 144-093. These results warrant the further clinical assessment of OC144-093 as an MDR reversing agent.
authors.affiliation: Dept. of Advanced Therapeutics, BC Cancer Agency, Vancouver, Canada.
authors.forename: Emma S
authors.initials: ES
authors.lastname: Guns
authors.forename: Tetyana
authors.initials: T
authors.lastname: Denyssevych
authors.forename: Ross
authors.initials: R
authors.lastname: Dixon
authors.forename: Marcel B
authors.initials: MB
authors.lastname: Bally
authors.forename: Lawrence
authors.initials: L
authors.lastname: Mayer
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000493:pharmacokinetics; D004347:Drug Interactions / Q000502:physiology; D018432:Drug Resistance, Multiple / Q000502:physiology*; D004358:Drug Therapy; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000493:pharmacokinetics*; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism; D017239:Paclitaxel / Q000493:pharmacokinetics*
chemical_list: D007093:Imidazoles; C410029:OC 144-093; D017239:Paclitaxel