Metabolic fate of sipoglitazar, a novel oral PPAR agonist with activities for PPAR-γ, -α and -δ, in rats and monkeys and comparison with humans in vitro.

Sipoglitazar is a novel anti-diabetic agent with triple agonistic activities on the human peroxisome proliferator-activated receptors, hPPAR-γ, -α, and -δ. The bioavailability for sipoglitazar was 95.0% and 72.6% in rats and monkeys respectively and sipoglitazar is hardly subject to first pass metabolism in either species. Following oral administration of [¹4C]sipoglitazar to rats, sipoglitazar and its metabolites were distributed to the rat tissues with relatively high concentrations in the liver and also to the target tissue, the adipose tissue. The major component was sipoglitazar in the plasma of rats and monkeys. In rats, sipoglitazar was mainly excreted into the feces via biliary excretion as sipoglitazar-G, while the major component was M-I-G in the urine and M-I in the feces of monkeys. In hepatocytes, the metabolism was not extensively advanced in rats and the main metabolites were M-I and sipoglitazar-G in humans, similar to the metabolic profile in monkeys. There was no metabolite specific for humans in vitro. In conclusion, the formation of M-I, M-I-G and sipoglitazar-G is considered to be crucial and sipoglitazar is presumed to be cleared primarily by oxidation and glucuronidation in humans, when examined in vivo and in vitro.

Marked impact of P-glycoprotein on the absorption of TAK-427 in rats.

The role of P-glycoprotein (P-gp, ABCB1) on the absorption process was investigated by drug-drug interaction studies of TAK-427 with P-gp inhibitors (erythromycin, ketoconazole or quinidine) in rats and by transport studies using rat multidrug resistance (MDR1) stably expressing cells and rat small intestine mounted in a Ussing-type chamber. TAK-427 showed high efflux activity with low permeability in rat MDR1a and MDR1b stably expressing cells and was revealed to be a typical substrate for P-gps. Although TAK-427 was mainly absorbed from the small intestine in rats, a large part of the dosed compound remained in the gastrointestinal tract. Orally co-administered P-gp inhibitors (50 mg/kg) increased the AUC of TAK-427 after a 5 mg/kg oral dose 5.4- to 18.3-fold, whereas orally administered P-gp inhibitors had a minor effect on the increase in the AUC of TAK-427 (1.3- to 2.2-fold) after a 0.5 mg/kg intravenous dose. Thus, the bioavailability of TAK-427 after oral administration in rats (7.3%) markedly increased when co-administered with P-gp inhibitors (28.6-57.6%). Moreover, the transport of TAK-427 was predominantly secretory throughout the rat small intestine and was inhibited by P-gp inhibitors. In conclusion, P-gp can markedly reduce the absorption of a typical P-gp substrate by its efflux activity throughout the absorption site.

Pharmacokinetic interaction between TAK-044, a new endothelin antagonist, and ciclosporin in rats.

The pharmacokinetic interaction between TAK-044 (cyclo[D-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-L-alanyl-L- alpha-aspartyl-D-2-(2-thienyl) glycyl-L-leucyl-D-tryptophyl] disodium, CAS 157380-72-8) and ciclosporin (CAS 59865-13-3) was investigated after concomitant intravenous (i.v.) administration in rats. After i.v. administration of 14C-labeled TAK-044 ([14C]TAK-044 alone at a dose of 3 mg/kg, the radioactivity concentration in the plasma was 1.65 micrograms/ml at 5 min and decreased biphasically with half-lives of 0.09 h and 0.39 h. AUC0-1 h was 0.38 microgram.h/ml. The pharmacokinetics of [14C]TAK-044 were affected dose-dependently by coadministration with ciclosporin. The AUC value for [14C]TAK-044 was increased 5- and 14-fold by the coadministration with cyclosporin at doses of 3 and 10 mg/kg, respectively. On the other hand, TAK-044 (3 and 10 mg/kg) did not change the pharmacokinetic parameters for ciclosporin (3 mg/kg). Biliary excretion is the major elimination route for both TAK-044 and cyclosporin. Ciclosporin delayed biliary excretion of [14C]TAK-044 in a dose-dependent manner, which might be due to inhibition of process(es) of hepato-biliary excretion of TAK-044. In conclusion, the AUC values for TAK-044 in rats are increased dose-dependently by coadministration with ciclosporin. Therefore, it may be necessary to adjust the dosage of the TAK-044 in combination with ciclosporin in the course of the first clinical trials.

Disposition of TAK-044, a new endothelin antagonist, in rats and dogs.

The disposition of TAK-044 (cyclo[D-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-L-alanyl-L- alpha-aspartyl-D-2-(2-thienyl) glycyl-L-leucyl-D-tryptophyl] disodium, CAS 157380-72-8), a new endothelin antagonist, was studied in rats and dogs by using 14C-labeled drug ([14C]TAK-044). After a single intravenous administration of [14C]TAK-044 at 3 mg/kg to rats and dogs, the concentrations of TAK-044 in plasma declined biphasically; t1/2 alpha and t1/2 beta were 0.03 and 1.10 h in rats, and 0.06 and 0.57 h in dogs, respectively. Plasma clearance and the volume of distribution at steady-state for TAK-044 were 1.66 l/h/kg and 2.09 l/kg in rats, 2.37 l/h/kg and 0.50 l/kg in dogs, respectively. In rats, TAK-044 was distributed widely into tissues, but the 14C concentrations in tissues except for the liver, kidney, and intestine were lower than that in plasma. The in vitro protein binding amounted to 91 to 92% in rat plasma and 88 to 90% in dog plasma. TAK-044 was hardly distributed into the erythrocytes of either species. TAK-044 was hardly metabolized, the radioactivity in plasma and excreta being mostly unchanged compound. Elimination of the radioactivity from the body was almost completed within 48 h in either species. The dosed radioactivity was excreted mostly in the feces via the hepatobiliary route. The rate of excretion of TAK-044 in the bile was dose-dependently prolonged.