Semaglutide is a GLP-1 analogue with 94% sequence homology to human GLP-1. Semaglutide acts as a GLP-1 receptor agonist that selectively binds to and activates the GLP-1 receptor, the target for native GLP-1.
GLP-1 is a physiological regulator of appetite and caloric intake, and the GLP-1 receptor is present in several areas of the brain involved in appetite regulation. Animal studies show that semaglutide distributed to and activated neurons in brain regions involved in regulation of food intake.
Semaglutide lowers body weight through decreased calorie intake. The effects are likely mediated by affecting appetite.
As with other GLP-1 receptor agonists, semaglutide stimulates insulin secretion and reduces glucagon secretion in a glucose-dependent manner. These effects can lead to a reduction of blood glucose.
Cardiac electrophysiology (QTc)
The effect of semaglutide on cardiac repolarization was tested in a thorough QTc trial. Semaglutide did not prolong QTc intervals at doses up to 1.5 mg at steady state.
Absolute bioavailability of semaglutide is 89%. Maximum concentration of semaglutide is reached 1 to 3 days post dose.
Similar exposure was achieved with subcutaneous administration of semaglutide in the abdomen, thigh, or upper arm.
The average semaglutide steady state concentration following subcutaneous administration of WEGOVY was approximately 75 nmol/L in patients with either obesity (BMI greater than or equal to 30 kg/m2) or overweight (BMI greater than or equal to 27 kg/m2). The steady state exposure of WEGOVY increased proportionally with doses up to 2.4 mg once-weekly.
The mean volume of distribution of semaglutide following subcutaneous administration in patients with obesity or overweight is approximately 12.5 L. Semaglutide is extensively bound to plasma albumin (greater than 99%) which results in decreased renal clearance and protection from degradation.
The apparent clearance of semaglutide in patients with obesity or overweight is approximately 0.05 L/h.
With an elimination half-life of approximately 1 week, semaglutide will be present in the circulation
for about 5 to 7 weeks after the last dose of 2.4 mg.
The primary route of elimination for semaglutide is metabolism following proteolytic cleavage of the peptide backbone and sequential beta-oxidation of the fatty acid sidechain.
The primary excretion routes of semaglutide-related material are via the urine and feces. Approximately 3% of the dose is excreted in the urine as intact semaglutide.
The effects of intrinsic factors on the pharmacokinetics of semaglutide are shown in Figure 2.
- Figure 2. Impact of intrinsic factors on semaglutide exposure
Data are steady-state dose-normalized average semaglutide exposures relative to a reference subject profile (non-Hispanic or Latino, white female aged 18 to less than 65 years, with a body weight of 110 kg and normal renal function, who injected in the abdomen). Body weight categories (74 and 143 kg) represent the 5% and 95% percentiles in the dataset.
Renal impairment did not impact the exposure of semaglutide in a clinically relevant manner. The pharmacokinetics of semaglutide were evaluated following a single dose of 0.5 mg semaglutide in a study of patients with different degrees of renal impairment (mild, moderate, severe, or ESRD) compared with subjects with normal renal function. The pharmacokinetics were also assessed in subjects with overweight (BMI 27-29.9 kg/m2) or obesity (BMI greater than or equal to 30 kg/m2) and mild to moderate renal impairment, based on data from clinical trials.
Hepatic impairment did not impact the exposure of semaglutide. The pharmacokinetics of semaglutide were evaluated following a single dose of 0.5 mg semaglutide in a study of patients with different degrees of hepatic impairment (mild, moderate, severe) compared with subjects with normal hepatic function.
In vitro studies have shown very low potential for semaglutide to inhibit or induce CYP enzymes, or to inhibit drug transporters.
The delay of gastric emptying with semaglutide may influence the absorption of concomitantly administered oral medications [see Drug Interactions (7.2)]. The potential effect of semaglutide on the absorption of co-administered oral medications was studied in trials at semaglutide 1 mg steady-state exposure. No clinically relevant drug-drug interactions with semaglutide (Figure 3) were observed based on the evaluated medications. In a separate study, no apparent effect on the rate of gastric emptying was observed with semaglutide 2.4 mg.
- Figure 3. Impact of semaglutide 1 mg on the pharmacokinetics of co-administered medications
Relative exposure in terms of AUC and Cmax for each medication when given with semaglutide compared to without semaglutide. Metformin and oral contraceptive drug (ethinylestradiol/levonorgestrel) were assessed at steady state. Warfarin (S-warfarin/R-warfarin), digoxin and atorvastatin were assessed after a single dose.
Abbreviations: AUC: area under the curve, Cmax : maximum concentration, CI: confidence interval.
In a 2-year carcinogenicity study in CD-1 mice, subcutaneous doses of 0.3, 1 and 3 mg/kg/day (2-, 8-, and 22-fold the maximum recommended human dose [MRHD] of 2.4 mg/week, based on AUC) were administered to the males, and 0.1, 0.3 and 1 mg/kg/day (0.6-, 2-, and 5-fold MRHD) were administered to the females. A statistically significant increase in thyroid C-cell adenomas and a numerical increase in C-cell carcinomas were observed in males and females at all dose levels (greater than or equal to 0.6 times human exposure).
In a 2-year carcinogenicity study in Sprague Dawley rats, subcutaneous doses of 0.0025, 0.01, 0.025 and 0.1 mg/kg/day were administered (below quantification, 0.2-, 0.4-, and 2-fold the exposure at the MRHD). A statistically significant increase in thyroid C-cell adenomas was observed in males and females at all dose levels, and a statistically significant increase in thyroid C-cell carcinomas was observed in males at greater than or equal to 0.01 mg/kg/day, at clinically relevant exposures.
Human relevance of thyroid C-cell tumors in rats is unknown and could not be determined by clinical studies or nonclinical studies [see Boxed Warning and Warnings and Precautions (5.1)]. Semaglutide was not mutagenic or clastogenic in a standard battery of genotoxicity tests (bacterial mutagenicity [Ames] human lymphocyte chromosome aberration, rat bone marrow micronucleus).
In a combined fertility and embryo-fetal development study in rats, subcutaneous doses of 0.01, 0.03 and 0.09 mg/kg/day (0.04-, 0.1-, and 0.4-fold the MRHD) were administered to male and female rats. Males were dosed for 4 weeks prior to mating, and females were dosed for 2 weeks prior to mating and throughout organogenesis until Gestation Day 17. No effects were observed on male fertility. In females, an increase in estrus cycle length was observed at all dose levels, together with a small reduction in numbers of corpora lutea at greater than or equal to 0.03 mg/kg/day. These effects were likely an adaptive response secondary to the pharmacological effect of semaglutide on food consumption and body weight.
Overview of Clinical Studies
The safety and efficacy of WEGOVY for chronic weight management (weight loss and maintenance) in conjunction with a reduced calorie diet and increased physical activity were studied in three 68-week, randomized, double-blind, placebo-controlled trials and one 68-week, randomized, double-blind, placebo withdrawal trial. In Studies 1, 2, and 3, WEGOVY or matching placebo was escalated to 2.4 mg subcutaneous weekly during a 16-week period followed by 52 weeks on maintenance dose. In Study 4, WEGOVY was escalated during a 20-week run-in period, and patients who reached WEGOVY 2.4 mg after the run-in period were randomized to either continued treatment with WEGOVY or placebo for 48 weeks.
In Studies 1, 2 and 4, all patients received instruction for a reduced calorie meal diet (approximately 500 kcal/day deficit) and increased physical activity counseling (recommended to a minimum of 150 min/week) that began with the first dose of study medication or placebo and continued throughout the trial. In Study 3, patients received an initial 8-week low-calorie diet (total energy intake 1000 to 1200 kcal/day) followed by 60 weeks of a reduced calorie diet (1200-1800 kcal/day) and increased physical activity (100 mins/week with gradual increase to 200 mins/week).
Study 1 was a 68-week trial that enrolled 1961 patients with obesity (BMI greater than or equal to 30 kg/m2) or with overweight (BMI 27-29.9 kg/m2) and at least one weight-related comorbid condition, such as treated or untreated dyslipidemia or hypertension; patients with type 2 diabetes mellitus were excluded. Patients were randomized in a 2:1 ratio to either WEGOVY or placebo. At baseline, mean age was 46 years (range 18-86), 74.1% were women, 75.1% were White, 13.3% were Asian and 5.7% were Black or African American. A total of 12.0% were Hispanic or Latino. Mean baseline body weight was 105.3 kg and mean BMI was 37.9 kg/m2.
Study 2 was a 68-week trial that enrolled 807 patients with type 2 diabetes and BMI greater than or equal to 27 kg/m2. Patients included in the trial had HbA1c 7-10% and were treated with either: diet and exercise alone or 1 to 3 oral anti‑diabetic drugs (metformin, sulfonylurea, glitazone or sodium-glucose co-transporter 2 inhibitor). Patients were randomized in a 1:1 ratio to receive either WEGOVY or placebo. At baseline, the mean age was 55 years (range 19-84), 50.9% were women, 62.1% were White, 26.2% were Asian and 8.3% were Black or African American. A total of 12.8% were Hispanic or Latino. Mean baseline body weight was 99.8 kg and mean BMI was 35.7 kg/m2.
Study 3 was a 68-week trial that enrolled 611 patients with obesity (BMI greater than or equal to 30 kg/m2) or with overweight (BMI 27-29.9 kg/m2) and at least one weight-related comorbid condition such as treated or untreated dyslipidemia or hypertension; patients with type 2 diabetes mellitus were excluded. The patients were randomized in a 2:1 ratio to receive either WEGOVY or placebo. At baseline, the mean age was 46 years, 81.0% were women, 76.1% were White, 19.0% were Black or African American and 1.8% were Asian. A total of 19.8% were Hispanic or Latino. Mean baseline body weight was 105.8 kg and mean BMI was 38.0 kg/m2.
Study 4 was a 68-week trial that enrolled 902 patients with obesity (BMI greater than or equal to 30 kg/m2) or with overweight (BMI 27-29.9 kg/m2) and at least one weight-related comorbid condition such as treated or untreated dyslipidemia or hypertension; patients with type 2 diabetes mellitus were excluded. Mean body weight at baseline for the 902 patients was 106.8 kg and mean BMI was 38.3 kg/m². All patients received WEGOVY during the run-in period of 20 weeks that included 16 weeks of dose escalation. Trial product was permanently discontinued before randomization in 99 of 902 patients (11%); the most common reason was adverse reactions (n=48, 5.3%); 803 patients reached WEGOVY 2.4 mg and were then randomized in a 2:1 ratio to either continue on WEGOVY or receive placebo. Among the 803 randomized patients, the mean age was 46 years, 79% were women, 83.7% were White, 13% were Black or African American, and 2.4% Asian. A total of 7.8% were Hispanic or Latino. Mean body weight at randomization (week 20) was 96.1 kg and mean BMI at randomization (week 20) was 34.4 kg/m2.
The proportions of patients who discontinued study drug in Studies 1, 2, and 3 was 16.0% for the WEGOVY-treated group and 19.1% for the placebo-treated group, and 6.8% of patients treated with WEGOVY and 3.2% of patients treated with placebo discontinued treatment due to an adverse reaction [see Adverse Reactions (6.1)]. In Study 4, the proportions of patients who discontinued study drug were 5.8% and 11.6% for WEGOVY and placebo, respectively.
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