Deborah Hilliard

Pharmacokinetics and pharmacodynamics of sitagliptin, an inhibitor of dipeptidyl peptidase IV, in healthy subjects: results from two randomized, double-blind, placebo-controlled studies with single oral doses.

Sitagliptin (MK‐0431 [(2R)‐4‐oxo‐4‐(3‐[trifluoromethyl]‐5,6‐dihydro[1,2,4]triazolo[4,3‐a]pyrazin‐7[8H]‐yl)‐1‐(2,4,5‐trifluorophenyl)butan‐2‐amine]) is an orally active, potent, and selective inhibitor of dipeptidyl peptidase IV (DPP‐IV) currently in phase III development for the treatment of type 2 diabetes.

Pharmacokinetics and Pharmacodynamic Effects of the Oral DPP-4 Inhibitor Sitagliptin in Middle-Aged Obese Subjects

Sitagliptin (MK‐0431) is an oral, potent, and selective dipeptidyl peptidase‐IV (DPP‐4) inhibitor developed for the treatment of type 2 diabetes. This multicenter, randomized, double‐blind, placebo‐controlled study examined the pharmacokinetic and pharmacodynamic effects of sitagliptin in obese subjects. Middle‐aged (45–63 years), nondiabetic, obese (body mass index: 30–40 kg/m2) men and women were randomized to sitagliptin 200 mg bid (n = 24) or placebo (n = 8) for 28 days. Steady‐state plasma concentrations of sitagliptin were achieved within 2 days of starting treatment, and >90% of the dose was excreted unchanged in urine. Sitagliptin treatment led to ∼90% inhibition of plasma DPP‐4 activity, increased active glucagon‐like peptide‐1 (GLP‐1) levels by 2.7‐fold (P < .001), and decreased post—oral glucose tolerance test glucose excursion by 35% (P < .050) compared to placebo. In nondiabetic obese subjects, treatment with sitagliptin 200 mg bid was generally well tolerated without associated hypoglycemia and led to maximal inhibition of plasma DPP‐4 activity, increased active GLP‐1, and reduced glycemic excursion.

Dipeptidyl Peptidase-4 Inhibitors Administered in Combination With Metformin Result in an Additive Increase in the Plasma Concentration of Active GLP-1

The aim of the study was to investigate the effects of a dipeptidyl peptidase‐4 (DPP‐4) inhibitor, of metformin, and of the combination of the two agents, on incretin hormone concentrations. Active and inactive (or total) incretin plasma concentrations, plasma DPP‐4 activity, and preproglucagon (GCG) gene expression were determined after administration of each agent alone or in combination to mice with diet‐induced obesity (DIO) and to healthy human subjects. In mice, metformin increased Gcg expression in the large intestine and elevated the plasma concentrations of inactive glucagon‐like peptide 1 (GLP‐1) (9–36) and glucagon. In healthy subjects, a DPP‐4 inhibitor elevated both active GLP‐1 and glucose dependent insulinotropic polypeptide (GIP), metformin increased total GLP‐1 (but not GIP), and the combination resulted in additive increases in active GLP‐1 plasma concentrations. Metformin did not inhibit plasma DPP‐4 activity either in vitro or in vivo. The study results show that metformin is not a DPP‐4 inhibitor but rather enhances precursor GCG expression in the large intestine, resulting in increased total GLP‐1 concentrations. DPP‐4 inhibitors and metformin have complementary mechanisms of action and additive effects with respect to increasing the concentrations of active GLP‐1 in plasma.

Multiple-dose pharmacodynamics and pharmacokinetics of anacetrapib, a potent cholesteryl ester transfer protein (CETP) inhibitor, in healthy subjects.

Cholesteryl ester transfer protein (CETP) is a plasma protein that catalyzes the heteroexchange of cholesteryl esters from high‐density lipoprotein (HDL) and triglycerides to apolipoprotein B–containing lipoproteins, especially very low–density lipoproteins (LDL‐C). 1, 2

Single‐dose pharmacokinetics and pharmacodynamics of anacetrapib, a potent cholesteryl ester transfer protein (CETP) inhibitor, in healthy subjects

AIMS Anacetrapib is an orally active and potent inhibitor of CETP in development for the treatment of dyslipidaemia. These studies endeavoured to establish the safety, tolerability, pharmacokinetics and pharmacodynamics of rising single doses of anacetrapib, administered in fasted or fed conditions, and to preliminarily assess the effect of food, age, gender and obesity on the single-dose pharmacokinetics and pharmacodynamics of anacetrapib. METHODS Safety, tolerability, anacetrapib concentrations and CETP activity were evaluated. RESULTS Anacetrapib was rapidly absorbed, with peak concentrations occurring at approximately 4 h post-dose and an apparent terminal half-life ranging from approximately 9 to 62 h in the fasted state and from approximately 42 to approximately 83 h in the fed state. Plasma AUC and C(max) appeared to increase in a less than approximately dose-dependent manner in the fasted state, with an apparent plateau in absorption at higher doses. Single doses of anacetrapib markedly and dose-dependently inhibited serum CETP activity with peak effects of approximately 90% inhibition at t(max) and approximately 58% inhibition at 24 h post-dose. An E(max) model best described the plasma anacetrapib concentration vs CETP activity relationship with an EC(50) of approximately 22 nm. Food increased exposure to anacetrapib; up to approximately two-three-fold with a low-fat meal and by up to approximately six-eight fold with a high-fat meal. Anacetrapib pharmacokinetics and pharmacodynamics were similar in elderly vs young adults, women vs men, and obese vs non-obese young adults. Anacetrapib was well tolerated and was not associated with any meaningful increase in blood pressure. CONCLUSIONS Whereas food increased exposure to anacetrapib significantly, age, gender and obese status did not meaningfully influence anacetrapib pharmacokinetics and pharmacodynamics.

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 B2 (cyclo‐oxygenase‐1 activity) in clotting whole blood on day 7 (0–24 hours postdose) was the primary endpoint. Inhibition of lipopolysaccharide‐induced prostaglandin E2 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 B2 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 E2 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 B2, while significantly decreasing the urinary prostacyclin metabolite, 2,3‐dinor‐6‐keto PGF1α. 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.

Demonstration of specific COX‐2 inhibition by MK‐966 in humans with supratherapeutic doses

Clinical Pharmacology & Therapeutics (1999) 65, 164–164; doi:

Effect of rofecoxib, etoricoxib, celecoxib, and naproxen on urinary excretion of prostanoids in elderly volunteers

COX‐2 inhibitors (COX2i) and nonselective NSAIDs affect systemic and renal prostaglandin synthesis and may have differential effects on vasoactive eicosanoids [prostacyclin, PGI2; thromboxane, TxB]. This study evaluated the effects of placebo (P), an NSAID [naproxen (N) 500 mg BID], and 3 COX2i [rofecoxib (R) 25 mg QD, etoricoxib (E) 90 mg QD, and celecoxib (C) 200 mg BID] on urinary prostanoids, 11‐dehydro TxB2 (TxB‐M; systemic TxB production measure), and 2,3 dinor 6‐keto PGF1α, (PGI‐M; systemic PGI2 production measure).

LBOVI-A-3

To pilot a pharmacodynamic (PD) model of short‐term androgen administration that may be used to predict long‐term effects of androgen administration in postmenopausal women. The study was specifically designed to identify biomarkers that evaluate early skin response to exogenous androgens. The clinical consequences of androgen administration include hirsutism and acne. Skin biopsies were performed to document morphological changes in the pilosebaceous unit (PSU) and gene expression changes (Taqman and microarray). Functional skin response was gauged by measuring sebum excretion rates (SER).