Pharmacokinetics, drug metabolism, and tissue distribution of CPX-351 in animals.

CPX-351, a liposomal encapsulation of cytarabine and daunorubicin at a synergistic 5:1 molar ratio, is indicated for adults with newly diagnosed, therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. In preclinical species, this article demonstrated (1) similar release of cytarabine and daunorubicin by CPX-351 in plasma; (2) similar patterns of metabolism of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal cytarabine/daunorubicin combination; (3) prolonged tissue exposure to CPX-351; (4) dramatically different tissue distribution of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination (tissue:plasma ratios generally <1 versus >1, respectively); and (5) dramatically lower unbound plasma and tissue concentrations of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination. Together, these results provide insight into the safety profile of CPX-351, as well as mechanisms that drive the improved efficacy observed for CPX-351 versus the conventional 7 + 3 cytarabine/daunorubicin regimen in clinical studies.

Pharmacokinetics, Metabolism and Disposition of [14C]XQ-1H After Intravenous Administration to Male Rats.

OBJECTIVE: This study describes the in vivo pharmacokinetics and metabolism of [14C]labeled XQ-1H in male rats. METHODS: XQ-1H is a methanesulfonate of XQ, 10-O-(N,N-dimethylaminoethyl)-ginkgolide B, a derivative of ginkgolide B (GB) with enhanced water solubility. Since it is very difficult to synthesize radiolabeled GB, the results obtained in this study may provide helpful insight to further ADME investigation of GB and its analogue compounds. After an i.v. administration of [14C]XQ-1H to male rats, XQ (the freebase form of XQ-1H) was extensively hydrolyzed, moderately metabolized, and mainly excreted in feces (71.5% of the dose) via the biliary route. RESULTS: The main enzyme mediated metabolic pathways were mono- and di-demthylation. Using the radiolabel form of XQ-1H, the temporal binding of XQ to red blood cells was observed. CONCLUSION: Binding of XQ to RBCs may lower the blood's viscosity and thus provide symptomatic improvement of ischemic stroke patients.

Disposition, metabolism and mass balance of [(14)C]apremilast following oral administration.

Apremilast is a novel, orally available small molecule that specifically inhibits PDE4 and thus modulates multiple pro- and anti-inflammatory mediators, and is currently under clinical development for the treatment of psoriasis and psoriatic arthritis. The pharmacokinetics and disposition of [(14)C]apremilast was investigated following a single oral dose (20 mg, 100 µCi) to healthy male subjects. Approximately 58% of the radioactive dose was excreted in urine, while faeces contained 39%. Mean C(max), AUC(0-∞) and t(max) values for apremilast in plasma were 333 ng/mL, 1970 ng*h/mL and 1.5 h. Apremilast was extensively metabolized via multiple pathways, with unchanged drug representing 45% of the circulating radioactivity and <7% of the excreted radioactivity. The predominant metabolite was O-desmethyl apremilast glucuronide, representing 39% of plasma radioactivity and 34% of excreted radioactivity. The only other radioactive components that represented >4% of the excreted radioactivity were O-demethylated apremilast and its hydrolysis product. Additional minor circulating and excreted compounds were formed via O-demethylation, O-deethylation, N-deacetylation, hydroxylation, glucuronidation and/or hydrolysis. The major metabolites were at least 50-fold less pharmacologically active than apremilast. Metabolic clearance of apremilast was the major route of elimination, while non-enzymatic hydrolysis and excretion of unchanged drug were involved to a lesser extent.

Recommendations on: internal standard criteria, stability, incurred sample reanalysis and recent 483s by the Global CRO Council for Bioanalysis.

"The Global CRO Council (GCC) for Bioanalysis was formed in an effort to bring together many CRO leaders to openly discuss bioanalysis and the regulatory challenges unique to the outsourcing industry"

Absorption of colesevelam hydrochloride in healthy volunteers.

OBJECTIVE: To assess whether colesevelam hydrochloride is absorbed in healthy volunteers. METHODS: A single-center, open-label, radiolabeled study was performed with 16 healthy volunteers. Subjects were administered non-radiolabeled colesevelam hydrochloride 1.9 g twice daily for 4 weeks, followed by a single dose of [14C]-colesevelam 2.4 g (480 pCi). These subjects continued to receive non-radioactive colesevelam 1.9 g twice daily for 4 days after administration of the radiolabeled dose. Blood, urine, and feces were collected immediately prior to administration of [14C]-colesevelam and at specified intervals after administration. The whole-blood equivalent concentration of colesevelam was calculated using data collected throughout the 96 hours following radiolabeled drug administration. The proportion of [14C]-colesevelam excreted through urine or feces was calculated based on the amount of radioactivity recovered up to 216 hours after the radiolabeled dose. RESULTS: The mean cumulative total recovery of [14C]-colesevelam in urine and feces was 0.05% and 74%, respectively. Excluding 2 subjects for whom cumulative recovery was <25%, the mean cumulative fecal recovery was 82%. The mean maximum whole-blood equivalent concentration of colesevelam was 0.165+/-0.10 microg equiv/g 72 hours after administration of [14C]-colesevelam, which was estimated to be 0.04% of the administered dose. All blood samples contained <4 times the number of background counts (dpm). CONCLUSIONS: The cumulative recovery data in urine and feces are consistent with the conclusion that colesevelam is not absorbed and is excreted entirely through the gastrointestinal system.