The multiple-dose pharmacokinetics, safety, and tolerability of oral bosentan, a selective endothelin receptor antagonist, were investigated in healthy male volunteers. In study A, an ascending-dose, double-blind, placebo-controlled trial, doses of 100, 200, 500, and 1000 mg bosentan or placebo were given once daily for 8 days as tablets (100 and 500 mg dose strength). In study B, a double-blind, placebo-controlled trial, 500 mg tablets of bosentan or placebo tablets were given once daily for 8 days with two additional single intravenous dose administrations of 250 mg bosentan 48 hours before the first and 24 hours after the last oral dose. The drug was very well tolerated. No effects on pulse rate, ECGs, or clinical laboratory tests were observed. Marginal effects on blood pressure were seen in subjects only when standing. The oral bioavailability of bosentan was 43% to 48%, with a small interindividual variability of 20%. Doses above 500 mg did not lead to significant further increases in plasma levels of bosentan. From the first to the last day of the oral treatment phase, plasma concentrations of bosentan decreased by 30% to 40% due to a 2-fold increase in plasma clearance. Absorption and plasma protein binding did not change. The 24-hour urinary excretion of 6 beta-hydroxycortisol was increased in parallel by approximately 1.7-fold, indicating induction of cytochrome P450 3A isozymes. The two metabolites of bosentan reached plasma concentrations well below those of bosentan and will most likely not contribute to the pharmacological activity.

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BackgroundThe CC-chemokine receptor 4 (CCR4) is thought potentially to play a critical role in asthma pathogenesis due to its ability to recruit type 2 T-helper lymphocytes to the inflamed airways. Therefore, CCR4 provides an excellent target for anti-inflammatory therapy.MethodsThe safety, tolerability, pharmacokinetics and pharmacodynamics of the CCR4 antagonist GSK2239633, N-(3-((3-(5-chlorothiophene-2-sulfonamido)-4-methoxy-1H-indazol-1-yl)methyl)benzyl)-2-hydroxy-2-methylpropanamide, were examined in healthy males. Two studies were performed: 1) an open-label, study in which six subjects received a single intravenous infusion of [14C]-GSK2239633 100 μg (10 kBq) (NCT01086462), and 2) a randomised, double-blind, placebo-controlled, cross-over, ascending dose study in which 24 subjects received single oral doses of GSK2239633 150–1500 mg (NCT01371812).ResultsFollowing intravenous dosing, plasma GSK2239633 displayed rapid, bi-phasic distribution and slow terminal elimination (t½: 13.5 hours), suggesting that GSK2239633 was a low to moderate clearance drug. Following oral dosing, blood levels of GSK2239633 reached Cmax rapidly (median tmax: 1.0–1.5 hours). Estimated GSK2239633 bioavailability was low with a maximum value determined of only 16%. Food increased GSK2239633 systemic exposure (as assessed by AUC and Cmax). Increases in AUC and Cmax were less than dose proportional. Adverse events were reported by three subjects (50%) following intravenous administration, and by 19 subjects (79%) following oral administration; most (46/47; 98%) events were mild/moderate in intensity. GSK2239633 1500 mg inhibited thymus- and activation-regulated chemokine-induced (TARC) actin polymerisation reaching a mean CCR4 occupancy of 74%.ConclusionIn conclusion, GSK2239633 was well-tolerated and capable of inhibiting TARC from activating the CCR4 receptor.

Mirabegron pharmacokinetics were linear after i.v. dosing (7.5 - 50 mg), but increased more than proportionally after oral dosing (25 - 150 mg) as a result of increased F. Sex differences in exposure could be explained by body weight and for oral dosing, also by F. Mirabegron was in general well tolerated up to the highest doses studied, 50 mg i.v. and 150 mg oral.

Sugammadex is a modified γ‐cyclodextrin which rapidly reverses rocuronium‐and vecuronium‐induced neuromuscular blockade. Previous studies suggest that sugammadex is mostly excreted unchanged via the kidneys. This single‐center, open‐label, non‐randomized study used 14C‐labeled sugammadex to further investigate the excretion, metabolic and pharmacokinetic (PK) profiles of sugammadex in six healthy male volunteers. 14C‐labeled sugammadex 4 mg/kg (0.025 MBq/kg of 14C‐radioactivity) was administered as a single intravenous bolus. Blood, urine, feces and exhaled air samples were collected at pre‐defined intervals for assessment of sugammadex by liquid chromatography‐mass spectrometry (LC‐MS) and for radioactivity measurements. Adverse events were also assessed. Excretion of sugammadex was rapid with ∼70% of the dose excreted within 6 h and ∼90% within 24 h. Less than 0.02% of radioactivity was excreted in feces or exhaled air. Ninety‐five percent of the radioactivity detected in urine could be attributed to sugammadex, as determined by LC‐MS, suggesting very limited metabolism of sugammadex. LC‐MS analysis of plasma samples found that sugammadex accounted for 100% of total 14C‐radioactivity in the plasma. In general, PK parameters determined from radioactivity and sugammadex plasma concentrations were very similar. Any adverse events were of mild‐to‐moderate intensity, and judged unrelated to sugammadex. These findings demonstrate that sugammadex is cleared rapidly, almost exclusively via the kidney, with minimal or no metabolism. Copyright © 2011 John Wiley & Sons, Ltd.