Inhibition of prostacyclin and thromboxane biosynthesis in healthy volunteers by single and multiple doses of acetaminophen and indomethacin.

This double-blind, randomized crossover study assessed the effect of acetaminophen (1000 mg every 8 hours) versus indomethacin (50 mg every 8 hours) versus placebo on cyclooxygenase enzymes (COX-1 and COX-2). Urinary excretion of 2,3-dinor-6-keto-PGF1α, (prostacyclin metabolite, PGI-M; COX-2 inhibition) and 11-dehydro thromboxane B2 (thromboxane metabolite, Tx-M; COX-1 inhibition) were measured after 1 dose and 5 days of dosing. Peak inhibition of urinary metabolite excretion across 8 hours following dosing was the primary end point. Mean PGI-M excretion was 33.7%, 55.9%, and 64.6% on day 1 and 49.4%, 65.1%, and 80.3% on day 5 (placebo, acetaminophen, and indomethacin, respectively). Acetaminophen and indomethacin inhibited PGI-M excretion following single and multiple doses (P = .004 vs placebo). PGI-M excretion inhibition after 1 dose was similar for indomethacin and acetaminophen, but significantly greater with indomethacin after multiple doses (P = .006). Mean Tx-M excretion was 16.2%, 45.2%, and 86.6% on day 1 and 46.2%, 58.4%, and 92.6% on day 5 (placebo, acetaminophen, and indomethacin, respectively). Tx-M excretion inhibition following 1 dose was reduced by acetaminophen (P ≤ .003). Indomethacin reduced Tx-M excretion significantly more than acetaminophen and placebo after single and multiple doses (P ≤ .001). Acetaminophen and indomethacin inhibited COX-1 and COX-2 following a single dose, but acetaminophen was a less potent COX-1 inhibitor than indomethacin.

The effects of laropiprant, a selective prostaglandin D2 receptor 1 antagonist, on the antiplatelet activity of clopidogrel or aspirin.

Laropiprant (LRPT) is being developed in combination with Merck's extended-release niacin (ERN) formulation for the treatment of dyslipidemia. LRPT, an antagonist of the prostaglandin PGD2 receptor DP1, reduces flushing symptoms associated with ERN. LRPT also has affinity for the thromboxane A2 receptor TP (approximately 190-fold less potent at TP compared with DP1). Aspirin and clopidogrel are two frequently used anti-clotting agents with different mechanisms of action. Since LRPT may potentially be co-administered with either one of these agents, these studies were conducted to assess the effects of steady-state LRPT on the antiplatelet activity of steady-state clopidogrel or aspirin. Bleeding time at 24 h post-dose (trough) was pre-specified as the primary pharmacodynamic endpoint in both studies. Two separate, double-blind, randomized, placebo-controlled, crossover studies evaluated the effects of multiple-dose LRPT on the pharmacodynamics of multiple-dose clopidogrel or aspirin. Healthy subjects were randomized to once-daily oral doses of LRPT 40 mg or placebo to LRTP co-administered with clopidogrel 75 mg or aspirin 81 mg for 7 days with at least a 21-day washout between treatments. In both studies, bleeding time and platelet aggregation were assessed 4 and 24 hours post-dose on Day 7. Comparability was declared if the 90% confidence interval for the estimated geometric mean ratio ([LRPT+clopidogrel]/clopidogrel alone or [LRPT+aspirin]/aspirin alone) for bleeding time at 24 hours post-dose on Day 7 was contained within (0.66, 1.50). Concomitant daily administration of LRPT 40 mg with clopidogrel 75 mg or aspirin 81 mg resulted in an approximate 4-5% increase in bleeding time at 24 hours after the last dose vs. bleeding time after treatment with clopidogrel or aspirin alone, demonstrating that the treatments had comparable effects on bleeding time. Percent inhibition of platelet aggregation was not significantly different between LRPT co-administered with clopidogrel or aspirin vs. clopidogrel or aspirin alone at 24 hours post-dose at steady state. At 4 hours after the last dose, co-administration of LRPT 40 mg resulted in 3% and 41% increase in bleeding time vs. bleeding time after treatment with aspirin or clopidogrel alone, respectively. Co-administration of LPRT with clopidogrel or aspirin was generally well tolerated in healthy subjects. Co-administration of multiple doses of LRPT 40 mg and clopidogrel 75 mg or aspirin 81 mg had no clinically important effects on bleeding time or platelet aggregation.

Effects of multiple doses of clarithromycin on the pharmacokinetics of laropiprant in healthy subjects.

Laropiprant is a selective antagonist of the prostaglandin D2 receptor subtype 1, and is primarily eliminated via glucuronidation with a minor contribution from oxidative metabolism via CYP3A. The effects of multiple oral doses of clarithromycin on the pharmacokinetics of laropiprant were investigated in an open-labeled, randomized, 2-period cross-over study. A single oral dose of 40 mg laropiprant was administered alone or coadministered with 500 mg clarithromycin b.i.d. on Day 5 of a 7-day clarithromycin regimen. Geometric mean ratios (90% confidence intervals) for AUC0-∞ and Cmax of laropiprant in the presence versus absence of clarithromycin were 1.39 (1.19, 1.62) and 1.46 (1.17, 1.80), respectively. No statistically significant differences were observed in Tmax (P= 0.543) or apparent terminal half-life (P= 0.502) of laropiprant, which implies that the effect of clarithromycin on laropiprant is largely a first-pass rather than a systemic effect. The results of this study suggest that laropiprant is not a sensitive CYP3A substrate, and strong CYP3A inhibitors like clarithromycin are not expected to have a clinically meaningful impact on the pharmacokinetics of laropiprant.

Effects of extended release niacin/laropiprant, laropiprant, extended release niacin and placebo on platelet aggregation and bleeding time in healthy subjects.

Laropiprant (LRPT) has been shown to reduce flushing symptoms induced by niacin and has been combined with niacin for treatment of dyslipidemia. LRPT, a potent PGD(2) receptor (DP1) antagonist that also has modest activity at the thromboxane receptor (TP), may have the potential to alter platelet function either by enhancing platelet reactivity through DP1 antagonism or by inhibiting platelet aggregation through TP antagonism. Studies of platelet aggregation ex vivo and bleeding time have shown that LRPT, at therapeutic doses, does not produce clinically meaningful alterations in platelet function. The present study was conducted to assess platelet reactivity to LRPT using methods that increase the sensitivity to detect changes in platelet responsiveness to collagen and ADP. The responsiveness of platelets was quantified by determining the EC(50) of collagen to induce platelet aggregation ex vivo. At 24 hours post-dose on Day 7, the responsiveness of platelets to collagen-induced aggregation was similar following daily treatment with extended-release niacin (ERN) 2 g/LRPT 40 mg or ERN 2 g. At 2 hours post-dose on Day 7, the EC(50) for collagen-induced platelet aggregation was approximately two-fold higher in the presence of LRPT, consistent with a small, transient inhibition of platelet responsiveness to collagen. There was no clinical difference between treatments for bleeding time, suggesting that this small effect on collagen EC(50) does not result in a clinically meaningful alteration of platelet function in vivo. The results of this highly sensitive method demonstrate that LRPT does not enhance platelet reactivity when given alone or with ERN.

Effects of laropiprant, a selective prostaglandin D(2) receptor 1 antagonist, on the pharmacokinetics of rosiglitazone.

Laropiprant (LRPT), a prostaglandin D(2) receptor-1 antagonist shown to reduce niacin-induced flushing symptoms, has been combined with niacin for treatment of dyslipidemia. This open-label, randomized, 2-period crossover study assessed the pharmacokinetics of single-dose rosiglitazone in the presence and absence of multiple-dose LRPT. Twelve healthy male and female subjects, 34-64 years of age, received two, once-daily oral treatments in random sequence separated by >/=3-day washout: (1) multiple-dose LRPT 40 mg/day for 7 days (Days 1 to 7) coadministered with single-dose rosiglitazone 4 mg on Day 6; (2) single-dose rosiglitazone 4 mg on Day 1. Comparability was declared because the 90% confidence interval (CI) for the AUC(0-infinity) geometric mean ratio (GMR; rosiglitazone + LRPT/rosiglitazone alone) [0.92 (0.86, 0.99)], was contained within prespecified bounds (0.70, 1.43). The C(max) GMR (90% CI) for rosiglitazone was 0.98 (0.95, 1.02). There was no evidence of clinically meaningful alterations in the pharmacokinetics of rosiglitazone, a probe CYP2C8 substrate, following coadministration of multiple-dose LRPT in healthy subjects. Therefore, findings suggest that LRPT does not inhibit CYP2C8-mediated metabolism.

Effect of laropiprant, a PGD2 receptor 1 antagonist, on estradiol and norgestimate pharmacokinetics after oral contraceptive administration in women.

Laropiprant is a prostaglandin D2 receptor 1 antagonist that is being developed in combination with niacin for the treatment of dyslipidemia. This randomized clinical study evaluated the effect of laropiprant on the pharmacokinetics of ethinyl estradiol (EE) and norelgestromin (NGMN), the principal circulating metabolite of norgestimate, in healthy women receiving 3 or more months of an oral contraceptive (Ortho Tri-Cyclen; Ortho-McNeil Pharmaceutical, Raritan, NJ), which contains EE and norgestimate. Twenty-one female subjects with normal menstrual cycles received the oral contraceptive on Days 1 to 21 during two consecutive contraceptive cycles. Subjects received double-blind 40 mg/day laropiprant or placebo on Days 1 to 21 of each contraceptive cycle. Plasma samples were collected predose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours postdose on Day 21 to measure area under the plasma concentration-time curve from 0 to 24 hours (AUC0-24hr) and maximum concentration observed in plasma (Cmax) of EE and NGMN. Comparability would be declared if the 90% confidence intervals for the geometric mean ratio of AUC0-24hr and Cmax in the absence and presence of laropiprant were within predefined bounds (0.80-1.25). The estimated geometric mean ratios (90% confidence intervals) of EE and NGMN, respectively, were 1.08 (1.04-1.13) and 0.97 (0.94-0.99) for AUC0-24hr and 1.16 (1.06-1.27) and 1.00 (0.94-1.06) for Cmax. The 90% confidence intervals for the geometric mean ratio of EE Cmax minimally exceeded the prespecified bounds; the other relevant pharmacokinetic parameters fell within the predefined bounds. Coadministration of 40 mg laropiprant with the oral contraceptive did not lead to clinically meaningful alterations in the pharmacokinetics of EE or NGMN.

Examination of the effect of increasing doses of etoricoxib on oral methotrexate pharmacokinetics in patients with rheumatoid arthritis.

The authors designed 2 randomized controlled studies to examine the effects of etoricoxib 60 to 120 mg daily on methotrexate pharmacokinetics in 50 rheumatoid arthritis (RA) patients on stable doses of methotrexate (7.5-20 mg). Patients received oral methotrexate at baseline and on days 7 and 14. In study 1, patients received etoricoxib 60 mg (days 1-7) and then 120 mg (days 8-14); in study 2, patients received etoricoxib 90 mg (days 1-7) and then 120 mg (days 8-14). For study 1, the AUC(0-infinity) geometric mean ratio (GMR) (90% confidence interval [CI]) for day 7 versus baseline was 1.01 (0.91, 1.12) for etoricoxib 60 mg; the area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)) GMR (90% CI) for day 14 was 1.28 (1.15, 1.42) for etoricoxib 120 mg. For study 2, the AUC(0-infinity) GMR (90% CI) for day 7 versus baseline was 1.07 (1.01, 1.13) for etoricoxib 90 mg; the AUC(0-infinity) GMR (90% CI) for day 14 was 1.05 (0.99, 1.11) for etoricoxib 120 mg. In summary, etoricoxib 60 and 90 mg had no effect on methotrexate plasma concentrations. Although no effect on methotrexate pharmacokinetics was observed with etoricoxib 120 mg in study 2, GMR AUC(0-infinity) fell outside the prespecified bounds in study 1. Standard monitoring of methotrexate-related toxicity should be continued when etoricoxib and methotrexate are administered concurrently, especially with doses >90 mg etoricoxib.

The effect of etoricoxib on the pharmacokinetics of oral contraceptives in healthy participants.

The pharmacokinetics of oral contraceptive (OC) components, ethinyl estradiol (EE) and norethindrone (NET), were evaluated after coadministration with etoricoxib in 3 double-blind, randomized, 2-period crossover studies of healthy women. There were 16, 39, and 24 participants enrolled in studies 1 (part I, part II), and 2, respectively. Each participant received triphasic OC (EE 35 microg/NET 0.5 mgx7 days, 0.75 mgx7 days, 1.0 mgx7 days) throughout each 28-day period. OC was coadministered with 21 days of etoricoxib daily followed by placebo for 7 days; the alternate period followed the reverse regimen (placebo to etoricoxib). Study 1 (part I) examined concurrent (morning) administration of OC/etoricoxib 120 mg, study 1 (part II) examined staggered (morning/night) administration of OC/etoricoxib 120 mg, and study 2 examined concurrent (morning) administration of OC/etoricoxib 60 mg. Coadministration of OC and etoricoxib 120 mg once daily was associated with a approximately 50% to 60% increase in EE concentrations, whereas etoricoxib 60 mg once daily was associated with a approximately 37% increase in EE concentrations. Coadministration of OC and etoricoxib was generally well tolerated. A clinically important change in NET AUC0-24 h was not observed. Adverse events included dyspepsia, diarrhea, headache, nausea, fatigue, loss of appetite, and taste disturbance.

Influence of laropiprant, a selective prostaglandin D2 receptor 1 antagonist, on the pharmacokinetics and pharmacodynamics of warfarin.

Laropiprant (LRPT), a prostaglandin D2 receptor 1 antagonist shown to reduce niacin-induced flushing symptoms, is being developed in combination with niacin for the treatment of dyslipidemia. This study assessed the pharmacokinetics/pharmacodynamics of single-dose warfarin in the presence/absence of multiple-dose LRPT. Thirteen subjects received 2 treatments in random order separated by > or =10-day washout: (1) multiple-dose LRPT 40 mg/d for 12 days (days -5 to 7) with coadministered single-dose warfarin 30 mg (day 6) and (2) single-dose warfarin 30 mg (day 1). R+- and S(-)-warfarin and international normalized ratio (INR) were assayed predose and up to 168 hours postdose. Comparability was declared if the 90% confidence intervals (CIs) for the geometric mean ratio (GMR; warfarin + LRPT/warfarin alone) of area under the plasma concentration curve from zero to infinity (AUC0-infinity) for R+- and S(-)-warfarin were contained within (0.80, 1.25). The estimated GMRs of AUC0-infinity (90% CIs) were 1.02 (0.96, 1.09) and 1.04 (0.98, 1.09) for R+- and S(-)-warfarin, respectively. The estimated GMRs of maximum plasma concentration (Cmax) (90% CIs) were 1.13 (1.02, 1.26) and 1.11 (0.99, 1.24) for R+- and S(-)-warfarin, respectively. The estimated GMRs of area under the prothrombin time INR curve from 0 to 168 hours on day 21 (INR AUC0-168 h) and average maximum observed prothrombin time INR (INRmax) were 1.02 (0.99, 1.05) and 1.04 (0.98, 1.10), respectively. There was no evidence of clinically meaningful alterations in the pharmacokinetics and pharmacodynamics (ie, INR) of R(+)- or S(-)-warfarin after coadministration of multiple-dose LRPT and single-dose warfarin.

Influence of taranabant, an orally active, highly selective, potent cannabinoid-1 receptor (CB1R) inverse agonist, on ethinyl estradiol and norelgestromin plasma pharmacokinetics.

Taranabant, an orally active, potent, and highly selective CB-1 receptor inverse agonist, is being developed for the treatment of obesity. This randomized, placebo-controlled, multiple-dose, crossover study evaluated the effect of taranabant on the pharmacokinetics of ethinyl estradiol and norelgestromin in healthy women receiving > or =3 months of therapy with oral contraceptives. Nineteen participants with normal menstrual cycles received oral contraceptives on days 1 to 21 during 2 consecutive contraceptive cycles. Participants received taranabant 6 mg/day or placebo on days 1 to 21 of each contraceptive cycle. Plasma samples were collected predose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours postdose on day 21 of each cycle for determination of AUC0-24 h and Cmax of ethinyl estradiol and norelgestromin. Lack of a clinically important effect was declared if the 90% confidence intervals for the geometric mean ratio of AUC0-24 h and Cmax in the absence and presence of taranabant were contained within the predefined bounds of (0.8, 1.25). The geometric mean ratios and 90% confidence intervals of ethinyl estradiol and norelgestromin, respectively, were 0.93 (0.87, 1.00) and 1.02 (0.96, 1.09) for AUC0-24 h and 0.95 (0.88, 1.01) and 0.95 (0.88, 1.01) for Cmax. In summary, coadministration of multiple-dose taranabant 6 mg with oral contraceptives did not lead to clinically meaningful alterations in the pharmacokinetic profiles of ethinyl estradiol or norelgestromin.

Influence of taranabant, a cannabinoid-1 receptor inverse agonist, on pharmacokinetics and pharmacodynamics of warfarin.

INTRODUCTION: The pharmacokinetic/pharmacodynamic effects of warfarin were assessed in the presence and absence of taranabant, an orally active, highly selective, potent, cannabinoid-1 receptor inverse agonist, which was being developed for the treatment of obesity. METHODS: Twelve subjects were assigned to two open-label treatments in fixed sequence separated by a 14-day washout. Treatment A was single-dose warfarin 30 mg on day 1. Treatment B was multiple-dose taranabant 6 mg each day for 21 days (days -14 to day 7) with coadministration of singledose warfarin 30 mg on day 1. Blood samples were collected predose and up to 168 hours postdose for assay of R(+)-and S(-)-warfarin and prothrombin time/international normalized ratio (PT/INR). RESULTS: The geometric mean ratios (GMR; warfarin+taranabant/warfarin 90% confidence interval [CI] primary endpoints) for area under the curve (AUC)(0-infinity) for R(+)-and S(-)-warfarin were 1.10 (90% CI: 1.03, 1.18) and 1.06 (90% CI: 1.00, 1.13), respectively. The GMRs (warfarin+taranabant/warfarin) for the maximum plasma concentration (C(max)) of S(-)-and R(+)-warfarin were 1.16 (90% CI: 1.05, 1.28) and 1.17 (90% CI: 1.07, 1.29), respectively. For R(+)-and S(-)-warfarin, the 90% CIs for AUC(0-infinity) GMRs fell within the prespecified bounds. Taranabant did not produce a clinically meaningful effect on PT/INR. CONCLUSION: No clinically significant alterations of the pharmacokinetics of R(+)-and S(-)-warfarin were seen following coadministration of multipledose taranabant 6 mg and single-dose warfarin 30 mg.

Evaluation of the pharmacokinetics of digoxin in healthy subjects receiving etoricoxib.

AIMS: Digoxin is a commonly prescribed cardiac glycoside with a narrow therapeutic index. The aim was to investigate whether the cyclooxygenase-2 selective nonsteroidal anti-inflammatory drug etoricoxib affects the steady-state pharmacokinetics of digoxin. METHODS: This was a double-blind, randomized, placebo-controlled, two-period cross-over study. In each period, 14 healthy volunteers ranging in age from 21 to 35 years received oral digoxin 0.25 mg daily and were randomized to either etoricoxib 120 mg or matching placebo tablets once daily for 10 days. Trough digoxin plasma concentrations were analysed by linear regression to examine digoxin accumulation over time. RESULTS: The geometric mean ratios (etoricoxib/placebo) for AUC(0-24h), C(max) and urinary excretion were 1.06 (90% confidence interval 0.97, 1.17), 1.33 (1.21, 1.46) and 1.10 (1.00, 1.20), respectively. The median (range) for digoxin T(max) (h) values with etoricoxib and placebo were 0.5 (0.5, 1.5) and 1.0 (0.5, 1.5), respectively. Steady-state digoxin plasma concentrations were achieved by day 7 in each treatment period. No serious adverse experiences were reported. CONCLUSIONS: Although etoricoxib 120 mg did produce an approximately 33% increase in digoxin C(max), this increase does not appear to be clinically meaningful, as cardiotoxicity with digoxin has been associated with elevations in steady-state rather than peak concentrations. From these results, it appears that etoricoxib does not cause any changes in digoxin steady-state pharmacokinetics that would necessitate a dose adjustment.

Comparative inhibitory activity of etoricoxib, celecoxib, and diclofenac on COX-2 versus COX-1 in healthy subjects.

We determined cyclo-oxygenase-1 and cyclo-oxygenase-2 inhibition in healthy middle-aged subjects (41-65 years) randomly assigned to four 7-day treatment sequences of etoricoxib 90 mg every day, celecoxib 200 mg twice a day, diclofenac 75 mg twice a day, or placebo in a double-blind, randomized, 4-period crossover study. Maximum inhibition of thromboxane B(2) (cyclo-oxygenase-1 activity) in clotting whole blood on day 7 (0-24 hours postdose) was the primary endpoint. Inhibition of lipopolysaccharide-induced prostaglandin E(2) in whole blood (cyclo-oxygenase-2 activity) was assessed on day 7 (0-24 hours postdose) as a secondary endpoint. Diclofenac had significantly greater maximum inhibition of thromboxane B(2) versus each comparator (P < .001); placebo 2.4% (95% confidence interval: -8.7% to 12.3%), diclofenac 92.2% (91.4% to 92.9%), etoricoxib 15.5% (6.6% to 23.5%), and celecoxib 20.2% (11.5% to 28.1%). Prostaglandin E(2) synthesis was inhibited with a rank order of potency of diclofenac > etoricoxib > celecoxib. In summary, at doses commonly used in rheumatoid arthritis, diclofenac significantly inhibits both cyclo-oxygenase-1 and cyclo-oxygenase-2, whereas etoricoxib and celecoxib significantly inhibit cyclo-oxygenase-2 and do not substantially inhibit cyclo-oxygenase-1.

Effects of etoricoxib and comparator nonsteroidal anti-inflammatory drugs on urinary sodium excretion, blood pressure, and other renal function indicators in elderly subjects consuming a controlled sodium diet.

This multicenter, double-blind, randomized, placebo-controlled, parallel-group study assessed renal function during dosing with etoricoxib 90 mg daily, celecoxib 200 mg twice daily, and naproxen 500 mg twice daily. Male and female subjects 60 to 81 years old (n = 85), in sodium balance on a controlled, normal sodium diet, were treated for 15 days. There were no clinically meaningful between-treatment differences in urinary sodium excretion, creatinine clearance, body weight, or serum electrolytes during the 2 weeks of treatment. Etoricoxib and celecoxib had no effect on the urinary thromboxane metabolite, 11-dehydrothromboxane B(2), while significantly decreasing the urinary prostacyclin metabolite, 2,3-dinor-6-keto PGF(1alpha). Decreases were greater for both metabolites following naproxen. Ambulatory systolic blood pressures were significantly higher than placebo for all treatments, with moderately greater increases for etoricoxib relative to other active treatments on day 14. Ambulatory diastolic blood pressures were significantly higher than placebo for etoricoxib and naproxen but not for celecoxib.

The effect of etoricoxib on the pharmacodynamics and pharmacokinetics of warfarin.

The effects of etoricoxib on pharmacodynamic and pharmacokinetic parameters of warfarin were determined in healthy men and women. Subjects titrated with warfarin to an international normalized ratio for prothrombin time of 1.4 to 1.7 during a 28-day prestudy period were randomly assigned in crossover fashion to be coadministered etoricoxib (120 mg) or matching placebo over two 21-day continuous periods. On day 21, a 24-hour pharmacokinetic profile of both S(-) and R(+) warfarin, as well as international normalized ratio values, were determined. Etoricoxib increased the international normalized ratio by 13% (90% confidence interval: 8%, 19%; P

MK-0703 (a cyclooxygenase-2 inhibitor) in acute pain associated with dental surgery: a randomized, double-blind, placebo- and active comparator-controlled dose-ranging study.

MK-0703 is a selective cyclooxygenase-2 inhibitor investigated for the treatment of acute pain and inflammation. The purpose of this single-dose, randomized, double-blind, double-dummy, placebo-controlled, parallel-group study was to compare MK-0703 12.5, 50, and 100 mg with ibuprofen 400 mg or placebo in patients who experienced moderate to severe pain after surgical removal of at least 2 third molars. Overall analgesic effect, duration of analgesic effect, time to onset of analgesic effect, peak analgesic effect, and tolerability were assessed over a 24-hour postdose period. The primary endpoint of this study was total pain relief over 8 hours postdose. The study included 121 patients (mean age, 23 yr); 16, 31, 28, 31, and 15 patients enrolled in the placebo, MK-0703 12.5 mg, MK-0703 50 mg, MK-0703 100 mg, and ibuprofen 400 mg groups, respectively. Both MK-0703 50 and 100 mg were significantly more effective than placebo for all endpoints (P < 0.01) and comparable with ibuprofen 400 mg. The onset of analgesic effect in the MK-0703 50 mg and 100 mg and ibuprofen 400 mg groups did not differ significantly from each other (P > 0.20). MK-0703 was generally well tolerated in single doses up to 100 mg. In summary, MK-0703 50 and 100 mg were efficacious in the treatment of postoperative dental pain and were indistinguishable from the active comparator, ibuprofen 400 mg.

Absorption, metabolism, and excretion of [14C]MK-0767 (2-methoxy-5-(2,4-dioxo-5-thiazolidinyl)-N-[[4-(trifluoromethyl)phenyl] methyl]benzamide) in humans.

MK-0767 (KRP-297; 2-methoxy-5-(2,4-dioxo-5-thiazolidinyl)-N-[[4-(trifluoromethyl)phenyl] methyl]benzamide) is a thiazolidinedione (TZD)-containing dual agonist of the peroxisome proliferator-activated receptors alpha and gamma that has been studied as a potential treatment for patients with type 2 diabetes. The metabolism and excretion of [14C]MK-0767 were evaluated in six human volunteers after a 5-mg (200 microCi) oral dose. Excretion of 14C radioactivity was found to be nearly equal into the urine (approximately 50%) and feces (approximately 40%). Elimination of [14C]MK-0767 was primarily by metabolism, with minimal excretion of parent compound into the urine (<0.5% of dose) and feces (approximately 14% of the dose). [14C]MK-0767 was the major circulating compound-related entity (>96% of radioactivity) through 48 h postdose. It was also found that approximately 91% of the total radioactivity area under the curve was due to intact MK-0767. Several minor metabolites were detected in plasma (<1% of radioactivity, each), formed by cleavage of the TZD ring and subsequent S-methylation and oxidation. All the metabolites excreted into urine were formed by TZD cleavage, whereas the major metabolite in feces was the O-demethylated derivative of MK-0767.

Pharmacokinetics of etoricoxib in patients with renal impairment.

The effect of renal insufficiency on the pharmacokinetics of etoricoxib, a selective inhibitor of cyclooxygenase-2, was examined in 23 patients with varying degrees of renal impairment (12 moderate [creatinine clearance between 30 and 50 mL/min/1.73 m2], 5 severe [creatinine clearance below 30 mL/min/1.73 m2], and 6 with end-stage renal disease requiring hemodialysis) following administration of single 120-mg oral doses of etoricoxib. Even the most severe renal impairment was found to have little effect on etoricoxib pharmacokinetics. The low recovery of etoricoxib in dialysate (less than 6% of the dose) supports that hemodialysis also has little effect on etoricoxib pharmacokinetics, and binding of etoricoxib to plasma proteins was generally unaffected by renal disease. Single doses of etoricoxib were generally well tolerated by patients with renal impairment. Based on pharmacokinetic considerations, dosing adjustments are not necessary for patients with any degree of renal impairment. However, because patients with advanced renal disease (creatinine clearance below 30 mL/min/1.73 m2) are likely to be very sensitive to any further compromise of renal function, and there is no long-term clinical experience in these patients, the use of etoricoxib is not recommended in patients with advanced renal disease.

An evaluation of the dose-dependent inhibition of CYP1A2 by rofecoxib using theophylline as a CYP1A2 probe.

This study was undertaken to determine whether rofecoxib can interfere with CYP1A2 activity in humans using theophylline as a probe substrate. Single oral doses of theophylline were administered to each of three panels of 12 healthy subjects receiving daily doses of rofecoxib for 7 days to examine the effect of rofecoxib administration on the absorption and disposition of theophylline. Each panel was administered doses of 12.5, 25, or 50 mg of rofecoxib or a matching placebo in a two-way, randomized, crossover fashion and administered a single oral 300-mg dose of theophylline on day 7 of rofecoxib or placebo administration. Plasma concentrations of theophylline were monitored for 48 hours postdose to assess differences in pharmacokinetics. All three commercially marketed doses of rofecoxib were found to slow the clearance of theophylline with no detectable effect on absorption. CL/F values for theophylline were estimated from AUC infinity and by point estimates from the concentrations of drug in plasma at 12 and 24 hours postdose. The point estimates of CL/F were found to be in agreement with those derived from AUC.