mk-0557 and Weight-Loss

To evaluate whether MK-0557, a highly selective, orally administered neuropeptide Y Y5 receptor antagonist, could limit weight regain after very-low-calorie diet (VLCD)-induced weight loss.. We enrolled 502 patients 18 to 65 years of age with a BMI of 30 to 43 kg/m2. Patients were placed on a VLCD (800 kcal/d liquid diet) for 6 weeks. Patients who lost>or=6% of initial body weight (n=359) were randomized to 52 weeks of 1 mg/d MK-0557 or placebo and maintained on a hypocaloric diet (300 kcal below weight maintenance requirements).. In randomized patients, the VLCD was associated with an average weight loss of 9.1 kg. After 12 weeks of double-blind treatment, weight began to gradually increase for both placebo- and MK-0557-treated patients. The mean weight change (95% confidence interval) from baseline at the end of the VLCD to Week 52 was +3.1 (2.1, 4.0) and +1.5 (0.5, 2.4) kg for patients treated with placebo and MK-0557, respectively. The difference of 1.6 kg between the two groups was significant (p=0.014). Secondary endpoints, such as blood pressure, lipid profile, insulin, and leptin, as well as waist circumference and quality-of-life measurements, did not show significant differences between MK-0557 and placebo treatments.. Although the difference in weight regain between placebo- and MK-0557-treated patients was statistically significant, the magnitude of the effect was small and not clinically meaningful. Antagonism of the neuropeptide Y Y5 receptor is not an efficacious treatment strategy for reducing weight regain after VLCD.

Topics: Adolescent; Adult; Aged; Body Mass Index; Caloric Restriction; Cyclohexanes; Double-Blind Method; Female; Humans; Male; Middle Aged; Neurotransmitter Agents; Obesity; Placebos; Pyrazoles; Receptors, Neuropeptide Y; Spiro Compounds; Weight Loss

Central counter-regulatory mechanisms, including those related to the orexigenic hormone neuropeptide Y (NPY), may limit the weight loss observed with conventional pharmacological monotherapy. This study evaluated whether blockade of the NPY Y5 receptor (NPY5R) with the selective antagonist MK-0557 potentiates sibutramine and orlistat weight loss effects.. Obese patients (497, BMI 30 to 43 kg/m2) were randomized to 1 of 5 treatment arms [placebo, n = 101; sibutramine 10 mg/d, n = 100; MK-0557 1 mg/d plus sibutramine 10 mg/d, n = 98; orlistat 120 mg TID, n = 99; MK-0557 1 mg/d plus orlistat 120 mg TID, n = 99] in conjunction with a hypocaloric diet for 24 weeks. The all-patients-treated population, imputing missing data using last observation carried forward, was used to assess weight loss from baseline.. The study was completed by 71% of patients in placebo, 76% in sibutramine alone, 79% in MK-0557 + sibutramine, 69% in orlistat alone, and 76% in MK-0557 + orlistat groups. Least squares (LS) mean difference [95% confidence interval (CI)] in weight change from baseline between MK-0557 + sibutramine and sibutramine alone was -0.1 (-1.6, 1.4) kg (p = 0.892) and between MK-0557 + orlistat and orlistat alone was -0.9 (-2.4, 0.6) kg (p = 0.250). Sibutramine alone induced a LS mean weight loss of -5.9 (-6.9, -4.9) kg vs. -4.6 (-5.7, -3.6) kg for orlistat (p = 0.097). There were no serious drug-related adverse events and MK-0557 was well tolerated.. Blockade of the NPY5R with the potent antagonist MK-0557 did not significantly increase the weight loss efficacy of either orlistat or sibutramine monotherapy.

Topics: Adolescent; Adult; Aged; Anti-Obesity Agents; Cyclobutanes; Cyclohexanes; Double-Blind Method; Drug Synergism; Drug Therapy, Combination; Female; Humans; Lactones; Male; Middle Aged; Obesity; Orlistat; Pyrazoles; Receptors, Neuropeptide Y; Spiro Compounds; Weight Loss