Byetta: Indications, Dosage, Precautions, Adverse Effects
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Byetta - Product Information

Manufacture: AstraZeneca
Country: Australia
Condition: Diabetes Mellitus, Type 2 Diabetes (Diabetes, Type 2)
Class: Antidiabetic agents, Incretin mimetics
Form: Liquid solution, Subcutaneous (SC)
Ingredients: exenatide, acetic acid - glacial, meta-Cresol, mannitol, sodium acetate, water for injection

exenatide

Name of the Medicine

BYETTA (exenatide) injection, solution.

The active ingredient in BYETTA is exenatide. Exenatide is a 39-amino acid peptide amide. It has the empirical formula C184H282N50O60S and molecular weight of 4186.6 Daltons. The amino acid sequence for exenatide is shown below.

H-His-Gly-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala-Val- Arg-Leu-Phe-Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser- NH2.

The CAS number for exenatide is 141732-76-5.

Description

BYETTA is a clear colourless solution.

BYETTA is supplied as a sterile, preserved solution for subcutaneous injection in a glass cartridge that has been assembled in an injector pen. Each millilitre contains 250 µg of synthetic exenatide. The excipients in BYETTA are meta-Cresol, mannitol, acetic acid-glacial, sodium acetate, and water for injections.

Pharmacology

Mechanism of action

Exenatide is a glucagon-like peptide-1 (GLP -1) receptor agonist that exhibits several antihyperglycaemic actions of glucagon-like peptide-1 (GLP-1). The amino acid sequence of exenatide partially overlaps that of human GLP-1. Exenatide has been shown to bind to and activate the known human GLP -1 receptor in vitro. This leads to an increase in both the glucose-dependent insulin synthesis and secretion from pancreatic beta-cells, by mechanisms involving cyclic AMP and/or other intracellular signalling pathways. As blood glucose concentrations decrease, insulin secretion subsides thereby reducing the potential risk of hypoglycaemia (see PRECAUTIONS).

Exenatide suppresses glucagon secretion which is known to be inappropriately elevated in type 2 diabetes. Lower glucagon concentrations lead to decreased hepatic glucose output. However, exenatide does not impair the normal glucagon response and other hormone responses to hypoglycaemia.

Exenatide slows gastric emptying thereby reducing the rate at which meal-derived glucose appears in the circulation.

Pharmacodynamic effects

Exenatide improves glycaemic control through the immediate and sustained effects of lowering both postprandial and fasting glucose concentrations in patients with type 2 diabetes. These pharmacodynamic actions occur through various mechanisms including stimulation of insulin secretion during hyperglycaemia, suppression of glucagon, and slowing of gastric emptying. In the insulin-comparator controlled studies, exenatide was associated with a significant reduction in postprandial blood glucose excursions compared with insulin glargine (p<0.0001) and biphasic insulin aspart (p<0.0001) (see Figure 1).

Figure 1. Summary of 7-point self-monitored blood glucose profiles at baseline and study endpoint in the insulin-comparator controlled studies


26-week study (ITT patients (n=549)) and 52-week study (ITT patients (n=501), last observation carried forward)

Beta-cell function: exenatide stimulates insulin release – clinical trial data show that this happens acutely with benefits in glycosylated haemoglobin evident within six weeks. No clinical data are available to suggest an improvement over time in beta-cell function. Most clinical benefit in glycaemic control is seen within 12 weeks of commencement. An increase in pancreatic islet cell mass has not been consistently demonstrated in animal models.

Pharmacokinetics

Absorption

Following subcutaneous administration to patients with type 2 diabetes, exenatide reaches median peak plasma concentrations in 2.1 h. Mean peak exenatide concentration (Cmax) was 211 pg/mL and overall mean area under the curve (AUC0-inf) was 1036 pg*h/mL following subcutaneous administration of a 10 мg dose of exenatide. Exenatide exposure (AUC) increased proportionally over the therapeutic dose range of 5 мg to 10 мg. The Cmax values increased less than proportionally over the therapeutic dose range of 5 мg to 10 мg. Similar exposure is achieved with subcutaneous administration of exenatide in the abdomen, thigh, or arm. Following subcutaneous administration of a single 10 мg dose of exenatide in the abdomen, thigh and arm, mean Cmax was 251 pg/mL, 220 pg/mL and 245 pg/mL, respectively; mean AUC was 1200 pg*h/mL, 1130 pg*h/mL and 1080 pg*h/mL, respectively.

Distribution

The mean apparent volume of distribution of exenatide following subcutaneous administration of a single dose of exenatide is 28.3 L

Metabolism and Elimination

Nonclinical studies have shown that exenatide is predominantly eliminated by glomerular filtration with subsequent proteolytic degradation. The mean apparent clearance of exenatide in humans is 9.1 L/h and the mean terminal half-life is 2.4 h. These pharmacokinetic characteristics of exenatide are independent of the dose. In most individuals, exenatide concentrations are measurable for approximately 10 h post-dose.

Special populations

Patients with renal impairment

In patients with mild to moderate renal impairment (creatinine clearance 30 to 80 mL/min), exenatide clearance was only mildly reduced compared to clearance in individuals with normal renal function. Clearance was significantly reduced to 0.9 L/h in patients with end-stage renal disease receiving dialysis compared with 9.1 L/h in healthy subjects (see PRECAUTIONS, CONTRAINDICATIONS and DOSAGE AND ADMINISTRATION).

Patients with hepatic insufficiency

No pharmacokinetic study has been performed in patients with a diagnosis of acute or chronic hepatic insufficiency. Exenatide is cleared primarily by the kidney; therefore hepatic dysfunction is not expected to affect blood concentrations of exenatide.

Gender, race, obesity

Gender, race or obesity has no significant influence on exenatide pharmacokinetics.

Elderly

Data in elderly are limited, but suggest no marked changes in exenatide exposure with increased age up to about 75 years old.

In patients with type 2 diabetes, administration of exenatide (10 µg) resulted in a mean increase of exenatide AUC by 36% in 15 elderly subjects aged 75 to 85 years compared to 15 subjects aged 45 to 65 years likely related to reduced renal function in the older age group (see DOSAGE AND ADMINISTRATION).

Clinical Trials

Use in combination with metformin and/or a sulfonylurea

Efficacy of exenatide in treatment of type 2 diabetes has been established in 5 pivotal placebo - or active comparator-controlled clinical trials, involving 2,496 patients, 1,498 of whom received exenatide. The primary objectives of these clinical trials were to evaluate glycaemic control, primarily as assessed by HbA1c. The secondary objectives included examining the effects of exenatide on fasting and postprandial plasma glucose concentrations, body weight, and fasting concentrations of circulating insulin, proinsulin, and lipids.

Exenatide treatment results in improvement in glycaemic control as measured by HbA1c over the dosing period with most benefit obtained by about the twelfth week of treatment (see Figure 2 and Table 1). In the three placebo controlled clinical trials, the mean (±SD) change from baseline in fasting plasma glucose was -0.4 ± 2.8 mmol/L and -0.6 ± 2.7 mmol/L with exenatide 5 and 10 мg BID, respectively, compared to an increase of 0.7 ± 2.9 mmol/L in the placebo arm at week 30. In addition, sustained reductions in postprandial glucose concentrations were observed during meal challenge tests at weeks 4 and 30.

In insulin comparator trials, exenatide reduced postprandial glucose excursions more than insulin glargine or biphasic insulin aspart, while insulin glargine reduced fasting glucose concentrations (p<0.0001) more than exenatide.

Patients treated with exenatide may exhibit progressive weight reduction. No specific studies on appetite or weight loss have been conducted. The precise mechanism of weight loss is unknown. The administration of exenatide is also associated with nausea and vomiting (see ADVERSE EFFECTS).

In three separate clinical trials when exenatide was used in combination with metformin, sulfonylurea, or a combination of both, significant improvements in glucose control were observed compared to placebo (see Table 1).

Table 1. Summary of efficacy results in placebo-controlled studies (ITT subjects)

NChange From Baseline to Week 30 (LS Mean ± SE)[1] HbA1c (%)
2993-112 (metformin)
Placebo1130.00 ± 0.106
Exenatide 5 мg [2]110-0.46 ± 0.112**
Exenatide 10 мg [3]113-0.86 ± 0.110**
2993-113 (sulfonylurea)
Placebo1230.06 ± 0.115
Exenatide 5 мg [2]125-0.51 ± 0.111**
Exenatide 10 мg [3]129-0.91 ± 0.110**
2993-115 (metformin + sulfonylurea)
Placebo2470.12 ± 0.079
Exenatide 5 мg [2]245-0.66 ± 0.079**
Exenatide 10 мg [3]241-0.88 ± 0.080**

Abbreviations: N=number of subjects; OAD=oral antidiabetic agent(s); SE=standard error of the mean; SU=sulfonylurea.

Note: The last observation carried forward method was applied to impute missing values at Week 4 through Week 30.

[1] Based on a general linear model with treatment, baseline HbA1c strata, and site as fixed effects for 2993-112 and 2993-113; based on a general linear model with treatment, baseline HbA1c strata, SU management group, and site as fixed effects for 2993-115.

[2] Exenatide 5 µg is exenatide 5 µg BID (4 weeks) followed by exenatide 5 µg BID (26 weeks);

[3] Exenatide 10 µg is exenatide 5 µg BID (4 weeks) followed by exenatide 10 µg BID (26 weeks).

*p<0.05, **p<0.01 for difference from placebo (p-values for the HbA1c endpoint are adjusted based on Fisher’s Protected Testing procedure).

When exenatide was used in combination with metformin and sulfonylurea similar improvements in glucose control were observed in two clinical trials, one comparing with insulin glargine and the other comparing with biphasic insulin aspart (see Table 2).

Table 2. Summary of efficacy results for exenatide active-comparator controlled studies (ITT subjects)

StudyNChange From Baseline to Endpoint Least Squares Mean ± Standard Error HbA1c (%)[1]
H80-MC-GWAA (metformin + sulfonylurea) – 26 weeks of treatment
Insulin glargine^260-1.05 ± 0.06*
Exenatide 10 µg [2]275-1.00 ± 0.06*
LS Mean Difference(95% CI (E-I))0.05(-0.09 to 0.20)
H80-MC-GWAD (metformin + sulfonylurea) – 52 weeks of treatment
Biphasic insulin aspart^^246-0.88 ± 0.07*
Exenatide 10 µg [2]248-0.98 ± 0.07*
LS Mean Difference(95% CI (E-I))-0.10(-0.28 to 0.08)

Abbreviations: N=number of subjects; SE=standard error of the mean; LS=least squares

Note: The last observation carried forward method was applied to impute missing values for HbA1c and fasting glucose.

[1] Based on a general linear model with treatment, country, and baseline value of the dependent variable as fixed effects.

[2] Exenatide 10 мg is exenatide 5 мg BID (4 weeks) followed by exenatide 10 мg BID for the remaining duration of the study.

CI (E-I)=the 2-sided, 95% Confidence Interval for the least squares (LS) mean difference between treatments (exenatide-insulin).

*p<0.0001 for difference within treatment, **p<0.0001 difference between treatment

^ GWAA: At week 26, the mean dose of insulin glargine was 25.0 Units/day.

^^ GWAD: At week 52, the mean dose of premixed biphasic insulin aspart was 24.4 Units/day.

The glucose lowering effect of exenatide can be seen immediately following the first injection. The average reduction in HbA1c (approximately 1%) is generally observable by 12 weeks after initiation of treatment. Figure 2 shows the mean HbA1c over time in patients with type 2 diabetes using exenatide or placebo together with metformin, sulfonylurea, or a combination of both. A sustained reduction of HbA1c has been shown through at least 52 weeks of therapy in a controlled study and 82 weeks in uncontrolled studies. In the 30 week placebo-controlled studies, 33.6% of patients using exenatide 10 µg BID together with metformin, sulfonylurea or a combination of both achieved HbA1c ≤7.0%. The ≤7.0% HbA1c goal was achieved by 46.4% of exenatide -treated versus 48% of insulin glargine-treated subjects in the 26 week study and by 31.7% of exenatide -treated and 24.1% of biphasic insulin aspart-treated subjects in the 52 weeks study (see Table 3).

Figure 2 Mean (SD) HbA1c by visit in placebo-comparator controlled studies of patients also taking metformin, sulfonylurea or a combination of both


The LOCF method was applied to impute missing HbA1c values at Week 4 through Week 30.

Patients randomised to exenatide 5 µg BID (4 weeks) followed by exenatide 5 µg BID (26 weeks) or exenatide 5 µg BID (4 weeks) followed by exenatide 10 µg BID (26 weeks).

Abbreviations: BID=twice daily before meals in the morning and evening; SD=standard deviation, ITT=intention to treat

Table 3. Number and proportion of subjects achieving HbA1c of ≤7.0%(ITT subjects)

Studies 2993-112, 2993-113, 2993-115 combined (30 weeks)Study H80-MC-GWAA(26 weeks)Study H80-MC-GWAD(52 weeks)
Exenatide*PlaceboExenatide*Insulin Glargine Exenatide*Biphasic insulin aspart
152 (33.6%)36 (7.9%)117(46.4%)110 (48.0%)72 (31.7%)57 (24.1%)

*Exenatide 10 µg, given as 5 µg BID for 4 weeks followed by 10 µg daily for remainder of study Includes subjects whose baseline HbA1c values were > 7%

Body weight: exenatide significantly reduced patient body weight in Phase 3 studies (placebo and insulin comparator controlled). Patients who continued in an uncontrolled open label extension to the placebo controlled studies continued to lose weight through 82 weeks of treatment. The long term outcomes (morbidity, mortality, or the clinical benefits) associated with these effects have not been studied.

Weight loss of 2.3 kg (2.6%, p<0.0001) was achieved in a 26-week insulin glargine comparator study and a loss of 2.5 kg (2.7%) in a 52-week biphasic insulin aspart comparator study whereas treatment with insulin was associated with weight gain (refer to Figure 3).

Figure 3. Least squares mean change in body weight in patients taking exenatide compared with insulin glargine or insulin aspart (ITT subjects)


The total estimated treatment difference (exenatide minus comparator) was -4.1 kg in the 26-week study and -5.4 kg in the 52-week study.

The results of three 30 weeks randomised triple-blind, placebo controlled trials showed significantly greater reductions from baseline in bodyweight with exenatide 5 or 10 мg BID daily than with placebo in patients receiving exenatide and metformin alone (-1.3 kg and -2.6 kg versus -0.2 kg) or exenatide and metformin plus a sulfonylurea (-1.6 kg and -1.6 kg vs -0.9 kg). In patients receiving exenatide and sulfonylurea only, only patients on exenatide 10 мg BID achieved a significantly greater reduction in body weight than placebo (-1.6 kg versus -0.8 kg) (also refer to Figure 4).

Figure 4. Change in body weight over time for the placebo-controlled studies - combined (ITT subjects, N=1446)


In patients receiving exenatide and metformin alone, weight reduction was statistically significant for patients with a baseline BMI <30 kg/m2 and ≥30kg/m2 for exenatide 10 µg BID but not for the exenatide 5 мg BID compared with placebo. For patients receiving exenatide and sulfonylurea alone, the change in body weight was statistically significant in patients with a baseline BMI <30 kg/m2 for exenatide 10 µg BID compared with placebo but not for exenatide 5 µg BID or patients with a BMI ≥30 kg/m2. For the exenatide with metformin and sulfonylurea patients, a statistically significant reduction in body weight was observed for each exenatide treatment (5 µg, BID and 10 µg, BID) compared with placebo with baseline BMI ≥30 kg/m2 but not for subjects with baseline BMI <30 kg/m2.

The observed weight loss was not necessarily secondary to nausea and other gastrointestinal side effects, as weight loss was also observed in those subjects who did not experience these adverse events.

Effect on lipids : exenatide has shown no adverse effects on lipid parameters. A trend for a decrease in triglycerides has been observed. An improvement in high density lipoprotein and an improvement in triglyceride levels have been correlated with greater weight loss at 82 weeks in exenatide treated patients. The long term outcomes (morbidity, mortality, or the clinical benefits) associated with these effects have not been studied.

Use in combination with a basal insulin

In a 30 week study, either exenatide (5 µg BID for 4 weeks, followed by 10 µg BID) or a placebo was added to insulin glargine (with or without metformin, pioglitazone or both). During the study both treatment arms titrated insulin glargine using an algorithm reflecting current clinical practice to a target fasting plasma glucose of approximately 5.6 mmol/L. The mean age of subjects was 59 years and the mean duration of diabetes was 12.3 years.

At the end of the study, exenatide (n=137) demonstrated a statistically significant reduction in HbA1c, the primary objective of the study. In relation to the secondary objective, body weight also was significantly reduced compared to placebo in patients receiving titrated insulin glargine. Based on additional secondary objectives, the proportion of patients achieving HbA1c <7% and ≤6.5% was greater in patients treated with exenatide compared to placebo. Reductions in insulin units/day, fasting serum glucose and postprandial glucose excursions after the morning and evening meal were greater with exenatide compared to placebo(see Table 4).

Table 4. Summary of efficacy results for exenatide in combination with basal insulin compared to placebo (ITT subjects)

Variable Least Squares Mean or Percentage of subjects Between Treatment Difference
Exenatide Placebo (95% CI)
Primary Objective
Haemoglobin (A1c%)
Baseline 8.38.5-0.20
Week 306.77.4-0.71 (-0.95 to -0.47)
Change -1.7-1.0 p<0.001
Secondary Objectives
Proportion reaching glycaemic target
Haemoglobin A1c <7.0% 56%29%-
Haemoglobin A1c ≤6.5% 42%13%-
Body weight (kg)
Baseline96.493.81.6
Week 3093.696.3-
Change-1.78+0.96-2.74 (-3.74 to -1.74)
Change in insulin dose at Week 30
U/day1320-6.5 (-12.24 to -0.79)
U/kg0.150.20-0.05 (-0.10 to 0.00)
Fasting serum glucose (mmol/L) Baseline
Baseline7.47.4-0.01
Week 306.16.5-
Change-1.28-0.87>-0.41 (-0.99 to 0.18)
Change in glucose excursion (mmol/L)
Morning 2-hour-2.0-0.2-1.8 (-2.5 to -1.2)
Midday 2-hour-0.5-0.3-0.3 (-0.8 to 0.3)
Evening 2-hour-1.60.1-1.7 (-2.3 to -1.1)

Abbreviations: CI=confidence interval.

When exenatide was added to existing basal insulin therapy (insulin glargine), the dose of basal insulin was decreased by 20% in patients with an HbA1c ≤8.0%, per protocol design in order to minimise the risk of hypoglycaemia. Both treatment arms were titrated to achieve target fasting plasma glucose levels. There were no clinically significant differences in the incidence of hypoglycaemic episodes in the exenatide group compared to the placebo group (25% and 30% respectively). There were no episodes of major hypoglycaemia in the exenatide arm.

Indications

Exenatide is indicated as adjunctive therapy to improve glycaemic control in patients with type 2 diabetes mellitus who are taking metformin, a sulfonylurea, or a combination of metformin and a sulfonylurea, or a combination of metformin and a basal insulin, but are not achieving adequate glycaemic control.

Contraindications

Exenatide is contraindicated in patients with known hypersensitivity to this product or any of its components, including meta-Cresol.

Exenatide should not be used in patients with end-stage renal disease or severe renal impairment (creatinine clearance <30 mL/min). Compared with healthy subjects, renal clearance of exenatide was significantly reduced in patients with end-stage renal disease receiving dialysis, resulting in poor gastrointestinal tolerability.

Precautions

Hypoglycaemia

When exenatide was used in combination with a sulfonylurea, the incidence of hypoglycaemia was increased over that of placebo in combination with a sulfonylurea. In the clinical studies patients on a sulfonylurea combination, with mild renal impairment had an increased incidence of hypoglycaemia compared to patients with normal renal function. To reduce the risk of hypoglycaemia associated with the use of a sulfonylurea, reduction in the dose of sulfonylurea may be considered (see DOSAGE AND ADMINISTRATION and ADVERSE EFFECTS).

Due to the glucose-dependent insulinotropic mechanism of action of exenatide, when used in combination with metformin alone, no increase in the incidence of hypoglycaemia was observed over that of placebo in combination with metformin (see DOSAGE AND ADMINISTRATION and ADVERSE EFFECTS).

Exenatide did not alter the counter-regulatory hormone response to insulin-induced hypoglycaemia in a randomised, double-blind, controlled study in healthy subjects.

General

Exenatide has not been studied in patients with severe gastrointestinal disease, including gastroparesis. Its use is commonly associated with gastrointestinal adverse effects, including nausea, vomiting, and diarrhoea. Therefore, the use of exenatide is not recommended in patients with severe gastrointestinal disease including gastroparesis and dumping syndrome.

The concurrent use of exenatide with D-phenylalanine derivatives, meglitinides, alpha-glucosidase inhibitors, orlistat, opioids, and anticholinergics has not been studied. Exenatide in combination with a thiazolidinedione is not recommended as there is limited experience.

Exenatide is not a substitute for insulin in insulin-requiring patients. Exenatide should not be used in patients with type 1 diabetes or for the treatment of diabetic ketoacidosis. The substitution of exenatide for insulin in insulin-requiring patients has not been extensively studied. In a 16 week exploratory study, which evaluated the safety of substituting exenatide for insulin in 33 patients with type 2 diabetes using insulin in combination with oral antidiabetic agents, almost 40% of subjects were unable to maintain glycaemic control (experienced an increase of HbA1c ≥0.5%) while on exenatide.

Since market introduction there have been some spontaneously reported cases of increased INR (International Normalized Ratio) with concomitant use of warfarin and exenatide, sometimes associated with bleeding (see INTERACTIONS WITH OTHER MEDICINES and ADVERSE EFFECTS, Spontaneous Data).

Exenatide should be used with caution and dose escalation from 5 µg to 10 µg should proceed conservatively in patients >70 years. The clinical experience in patients >75 years is very limited.

Altered Renal Function

There have been rare, spontaneously reported events of acute renal failure, worsened chronic renal failure, renal impairment, or increased serum creatinine among patients using exenatide. These events mostly occurred in patients also receiving one or more pharmacologic agents known to potentially affect renal function or hydration status and/or experiencing events of nausea, vomiting, diarrhoea, and/or dehydration. Concomitant agents included angiotensin converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs, and diuretics. For many events, reversibility has been observed with appropriate treatment (see ADVERSE EFFECTS, Spontaneous Data).

Pancreatitis

Recognised risk factors for pancreatitis include a past history of pancreatitis, gallstones, alcoholism and severe hypertriglyceridaemia. Clinical judgement should be exercised when selecting anti-diabetic treatments, including exenatide, for these patients. The change in risk of recurrent pancreatitis in patients with a past history of pancreatitis who receive exenatide is not known. There have been rare, spontaneously reported events of acute pancreatitis, including fatal cases of haemorrhagic or necrotising pancreatitis in patients who have received exenatide.

Cases of haemorrhagic or necrotising pancreatitis have been reported across the adult age range (18 years and over, including the elderly). There are no early signs or symptoms that distinguish cases that will become acute haemorrhagic or necrotising pancreatitis from the less severe form of pancreatitis. This potential should be considered in patients treated with exenatide who manifest symptoms and signs suggestive of pancreatitis. Patients should be informed of the characteristic symptom of acute pancreatitis: persistent, severe abdominal pain. Patients and their caregivers should be advised to report immediately to their doctor such abdominal pain particularly if associated with vomiting or diarrhoea. Generally, resolution of pancreatitis has been observed with supportive treatment. If pancreatitis is suspected, exenatide and other potentially suspect medications should be discontinued and not recommenced unless pancreatitis has been excluded.

Weight Loss

Rapid weight loss at a rate of >1.5 kg per week has been reported in patients treated with exenatide. Weight loss of this rate may have harmful consequences.

Effects on fertility

Animal studies did not indicate direct harmful effects with respect to fertility. Male and female fertility was unaffected in mice treated with exenatide at SC doses up to 760 мg/kg/day, 500 times the clinical exposure at 20 мg/day based on AUC.

Use in Pregnancy – Category C

Exenatide is not recommended for use during pregnancy. No specific studies have been conducted in pregnant women.

Data on a limited number of exposed pregnancies indicate no adverse effects of exenatide on pregnancy or on the health of the foetus/new born child. To date, no other relevant epidemiological data are available.

Potential embryofetal effects were assessed with SC doses of exenatide during organogenesis in mice at 6, 68 and 760 мg/kg/day and in rabbits at 0.2, 2, 22, 156 and 260 мg/kg/day, giving respective exposures approximately 3, 30 and 500 times (mouse) and 0.2, 5, 200, 1400 and 3500 times (rabbit) the clinical exposure at 20 мg/day. A low incidence of abortions and decreased fetal growth occurred in mice and rabbits at ≥68 and 22 мg/day, respectively, which also caused a decrease in food consumption and body weight gain in dams. Alterations of skeletal ossification were observed in rabbits at ≥2 мg/kg/day as a result of decreased food intake. Wavy ribs were seen in mice at 760 мg/kg/day. Fetal umbilical hernias were increased in rabbits at ≥22 мg/kg/day. There was minimal placental transfer of exenatide in animal studies in vivo or in human placental tissues in vitro. The fetal findings were probably secondary to effects on the dam.

High doses of exenatide administered to mice during gestation and lactation caused stillbirths, an increase in neonatal deaths and a decrease in neonatal growth at exposures 500 times the clinical exposure at 20 мg/day. The no observable effect level for peri-neonatal effects was 68 мg/kg/day, giving exposures 30 times the clinical exposure (see Carcinogenicity, Genotoxicity, Effects on Fertility).

Use in lactation

It is unknown whether exenatide is excreted in human milk. In lactating mice given high doses of exenatide, low concentrations of exenatide were detected in milk (2.5% of plasma level). Neonatal deaths were increased in lactating mice at high doses (see Use in Pregnancy). Exenatide should be administered to nursing women only if the potential benefit to the mother justifies the potential risk to the infant.

Genotoxicity

Exenatide was not genotoxic in bacterial reverse mutation assays, in vitro chromosomal aberration tests in Chinese hamster ovary cells or a mouse micronucleus assay.

Carcinogenicity

In female rats given exenatide for 2 years, an increased incidence of benign thyroid C-cell adenomas was observed at the highest dose (250 µg/kg/day), a dose that produced an exenatide plasma exposure 110 times the human clinical exposure at 20 мg/day. There was no tumorigenic response in male rats or either sex of mice at exposures 80 (mouse) and 110 (rat) times the human exposure.

Paediatrics

The safety and effectiveness of exenatide has not been established in children under 18 years of age.

Use in elderly

No dosage adjustments are necessary for use of exenatide in elderly patients. Subjects aged up to 75 years were enrolled in the 5 placebo- and active comparator-controlled pivotal clinical studies. A total of 333 subjects aged 65 years or older received exenatide in these studies. There were no apparent age-related differences in the change in HbA1c values from baseline to endpoint for subjects treated with exenatide during these studies.

Use in Renal Impairment

In patients with mild to moderate renal impairment (creatinine clearance >30 to 80 mL/min), exenatide clearance was only mildly reduced compared to clearance in individuals with normal renal function. Patients with moderate renal impairment (creatinine clearance >30 to 50 mL/min) have been noted to have an increase in the AUC of exenatide. As the risk of adverse events is dose-dependant, caution is recommended in this population (see CONTRAINDICATIONS).

Effects on ability to drive and use machines

When Exenatide is used in combination with a sulfonylurea, patients should be advised to take precautions to avoid hypoglycaemia while driving and using machines.

Interactions with other Medicines

Exenatide stimulates insulin release. This should be considered when insulin secretagogues are used (for use with sulfonylurea, see CLINICAL TRIALS).

Exenatide slows gastric emptying, as part of its mechanism of action. This has the potential for interaction with orally administered medicines. Exenatide should be used with caution in patients receiving oral medications that require rapid gastrointestinal absorption or medication associated with local gastrointestinal irritation such as bisphosphonates or tetracyclines. Gastroresistant formulations containing substances sensitive to degradation in the stomach, such as proton pump inhibitors, should be taken at least 1 hour before or more than 4 hours after exenatide injection. For oral medications that are particularly dependent on threshold concentrations for efficacy, such as contraceptives and antibiotics, patients should be advised to take those medicines at least 1 hour before exenatide injection. If such medicines are to be administered with food, patients should be advised to take them with a meal or snack when exenatide is not administered.

Paracetamol

Paracetamol was used as a model medicinal product to evaluate the effect of exenatide on gastric emptying. When 1000 mg paracetamol was given with 10 µg exenatide (0 h) and 1 h, 2 h and 4 h after exenatide injection, paracetamol AUCs were decreased by 21%, 23%, 24% and 14% respectively; Cmax was decreased by 37%, 56%, 54% and 41% respectively; Tmax was increased from 0.6 h in the control period to 0.9 h, 4.2 h, 3.3 h and 1.6 h respectively. Paracetamol AUC, Cmax and Tmax were not significantly changed when paracetamol was given 1 hour before exenatide injection. No adjustment to paracetamol dosing is required based on these study results.

HMG CoA reductase inhibitors

The AUC and Cmax of lovastatin, a HMG CoA reductase inhibitor, were decreased approximately 40% and 28%, respectively, and Tmax was delayed by about 4 h when Exenatide (10 µg BID) was administered concomitantly with a single dose of lovastatin (40 mg) compared with lovastatin administered alone. In the 30-week placebo controlled clinical trials, concomitant use of Exenatide and HMG CoA reductase inhibitors was not associated with consistent changes in lipid profiles. Although no predetermined dose adjustment is required, one should be aware of possible changes in LDL-C or total cholesterol. Lipid profiles should be monitored regularly.

Warfarin, Digoxin, Lisinopril

In a controlled clinical pharmacology study in healthy volunteers, a delay in warfarin Tmax of about 2 h was observed when warfarin was administered 30 min after exenatide. No clinically relevant effects on Cmax or AUC were observed (see PRECAUTIONS and ADVERSE EFFECTS, Spontaneous Data).

No clinically relevant interactions were observed with digoxin and lisinopril.

Ethinyl estradiol and levonorgestrel

Administration of a combination oral contraceptive (30 µg ethinyl estradiol plus 150 µg levonorgestrel) one hour before exenatide did not alter the AUC, Cmax or Cmin of either ethinyl estradiol or levonorgestrel. Administration of the oral contraceptive 30 minutes after exenatide did not affect AUC but resulted in a reduction in the Cmax of ethinyl estradiol by 45%, and Cmax of levonorgestrel by 27-41%, and a delay in Tmax by 2-4 h due to delayed gastric emptying. The reduction in Cmax is of limited clinical relevance and no adjustment of dosing of oral contraceptives is required.

Adverse Effects

Use with metformin and/or a sulfonylurea

The safety of exenatide has been evaluated in over 2500 exenatide -treated subjects in the completed clinical pharmacology, efficacy and safety studies, comprising 1729 subject years. Overall, 87% of exenatide-treated subjects experienced at least one treatment emergent adverse event, compared with 72% of insulin- and 64% of placebo-treated subjects. Among exenatide-treated subjects, nausea was the most common event (52%), followed by hypoglycaemia (27%) and vomiting (19%).

The incidence of withdrawal due to adverse events was 8% for exenatide-treated patients and 2% for placebo-treated or insulin-treated patients in the long -term controlled trials (26 weeks or longer). The most common adverse events leading to withdrawal for exenatide-treated patients were nausea (3% of patients) and vomiting (1%). For placebo-treated or insulin-treated patients, <1% withdrew due to nausea and 0% due to vomiting.

Exenatide-treated patients in the open-label extension studies at 82 weeks experienced similar types of adverse events to those observed in the long term controlled trials of 26 weeks or more.

Table 5 lists the adverse reactions reported from Phase 3 placebo, insulin glargine and 30% soluble insulin aspart/70% insulin aspart protamine crystal (biphasic insulin aspart) - comparator controlled studies in which the patients received metformin, a sulfonylurea or a combination of both in addition to exenatide or comparator.

The table presents adverse reactions that occurred with an incidence ≥5% and more frequently among exenatide-treated patients than insulin- or placebo-treated patients. The table also includes adverse reactions that occurred with an incidence ≥1% and with a statistically significantly higher and/or ≥2X incidence among exenatide-treated patients than insulin- or placebo-treated patients.

The reactions are listed below as MedDRA preferred term by system organ class and absolute frequency.

Table 5. Adverse reactions reported in phase 3 placebo or active- comparator controlled studies.

Body System/Adverse Reaction TermsFrequency of Occurrence
EventsExenatide N=1498Insulin N=515Placebo N=483
Metabolism and nutrition disorders
Hypoglycaemia (with metformin and a sulfonylurea) 1,239.6%55.9%12.6%
Hypoglycaemia (with a sulfonylurea)325.2%data not available 3.3%
Decreased appetite3.1%0.2%0.2%
Nervous system disorders
Headache17.9%7.0%6.2%
Dizziness6.9%1.6%6.2%
Gastrointestinal disorders
Nausea44.3%4.7%18.0%
Vomiting14.0%3.5%3.7%
Diarrhoea12.0%2.5%6.8%
Dyspepsia4.7%0.4%2.1%
Abdominal pain43.4%1.0%2.5%
Gastroesophageal reflux disease2.5%0.2%0.8%
Abdominal distension1.5%0.2%0.8%
Skin and subcutaneous tissue disorders
Hyperhidrosis12.5%1.0%1.2%
General disorders and administrative site conditions
Feeling jittery6.0%0.2%4.1%
Asthenia12.8%1.4%1.7%

1 In insulin comparator controlled studies in which metformin and a sulfonylurea were concomitant medications, the incidence for these terms was similar for insulin and Exenatide treated patients.

2 Includes data from placebo-controlled and insulin-controlled studies, for which the definition of hypoglycaemia differed. N=1021 for subjects using metformin and sulfonylurea.

3 N=254 for subjects using a sulfonylurea.

4 Includes reported events of abdominal pain and upper abdominal pain

In the three 30-week controlled trials of exenatide add-on to metformin and/or sulfonylurea, adverse events with an incidence ≥5% (excluding hypoglycemia; see Table 6) that occurred more frequently in exenatide-treated patients compared with placebo-treated patients are summarized in Table 6.

Table 6. Frequent treatment-emergent adverse events (≥5% incidence and greater incidence with exenatide treatment) excluding hypoglycemia*

Placebo BID N=483 %All Exenatide BID N=963 %
Nausea1844
Vomiting413
Diarrhea613
Feeling Jittery49
Dizziness69
Headache69
Dyspepsia36

* In three 30-week placebo-controlled clinical trials.

Hypoglycaemia

Use with a sulfonylurea, metformin or both

In 30-week placebo-controlled studies in patients treated with exenatide in combination with a sulfonylurea, or exenatide in combination with a sulfonylurea and metformin, the incidence of hypoglycaemia was increased over that of placebo in combination with a sulfonylurea, or placebo in combination with a sulfonylurea and metformin (see PRECAUTIONS) and appeared to be dependent on the doses of both exenatide and the sulfonylurea. Most episodes of hypoglycaemia were mild to moderate in intensity, and all resolved with oral administration of carbohydrate (see Table 7). In contrast, when exenatide was used in combination with metformin, no increase in the incidence of hypoglycaemia was observed over that of placebo in combination with metformin.

Table 7. Incidence (%) of hypoglycaemia by concomitant antidiabetic therapy in 30-week placebo controlled studies

PlaceboExenatidePlaceboExenatidePlaceboExenatide
BID5 мg BID 10 мg BID BID5 мg BID 10 mg BID BID5 мg BID 10 мg BID
With metforminWith sulfonylureaWith met/sfu
N113110113123125129247245241
Hypoglycaemia5.3%4.5%5.3%3.3%14.4%35.7%12.6%19.2%27.8%

Exenatide and placebo were administered before the morning and evening meals.

Abbreviations: BID, twice daily; met/sfu, metformin and a sulfonylurea.

In the long-term active comparator (26 weeks or greater) studies in which all patients also received both metformin and a sulfonylurea the incidence of hypoglycaemia was similar for exenatide and insulin treatment (either insulin glargine or biphasic insulin aspart). Exenatide patients reported fewer episodes of nocturnal hypoglycaemia than insulin patients in both insulin glargine-comparator study (p<0.001) and the biphasic insulin aspart-comparator study (p=0.0384).

To reduce the risk of hypoglycaemia associated with the use of a sulfonylurea, reduction in the dose of sulfonylurea may be considered (see DOSAGE AND ADMINISTRATION).

Use with insulin

When exenatide was added to existing titrated basal insulin therapy (insulin glargine), the incidence and types of adverse events observed were similar to those seen in the controlled clinical trials with exenatide in combination with metformin and/or sulfonylurea (see Table 8).

Table 8. Treatment-emergent adverse events (≥5% incidence in exenatide treated patients)

System Organ Class Preferred TermFrequency of Occurrence
EventsExen + Ins Glar N=137Placebo + Ins Glar N=122
Gastrointestinal disorders
Nausea56(41%)10 (8%)
Vomiting25(18%)5 (4%)
Diarrhoea25(18%)10 (8%)
Dyspepsia9 (7%)2 (2%)
Constipation14 (10%)2 (2%)
General disorders and administrative site conditions
Asthenia7 (5%)1 (1%)
Infections and infestations
Nasopharyngitis8 (6%)6 (5%)
Upper respiratory tract infection11 (8%)9 (7%)
Musculoskeletal and connective tissue disorders
Back pain9 (7%)2 (2%)
Nervous system disorders
Headache19 (14%)5 (4%)
Respiratory, thoracic, and mediastinal disorders
Cough7 (5%)7 (6%)

Abbreviations: Exen=exenatide; ILPS=insulin lispro protamine suspension; Ins Glar=insulin glargine.

Nausea

The most frequently reported adverse reaction, mild to moderate nausea, occurred in a dose-dependent fashion. With continued therapy, the frequency and severity decreased in most patients who initially experienced nausea.

Immunogenicity

Consistent with the potentially immunogenic properties of protein and peptide pharmaceuticals, patients may develop anti-exenatide antibodies following treatment with exenatide. In most patients who develop antibodies, antibody titres diminish over time and remain low through 82 weeks.

In the three long-term placebo controlled trials 38% of patients had low titre anti-exenatide antibodies at 30 weeks. For this group, the level of glycaemic control (HbA1c) was generally comparable to that observed in those without antibody titres. An additional 6% of patients had higher titre antibodies at 30 weeks. In about half of this 6% (3% of the total patients given exenatide in the controlled studies), the glycaemic response to exenatide appeared diminished; the remainder had a glycaemic response consistent with that of patients without antibodies. Patients who developed anti-exenatide antibodies tend to have more injection site reactions (for example: redness of skin and itching), but otherwise had similar rates and types of adverse events as those with no anti-exenatide antibodies. In the insulin -comparator controlled trials comparable efficacy and adverse events were observed in exenatide treated patients with and without antibody titres. Examination of antibody-positive specimens from one lon -term uncontrolled study revealed no significant cross-reactivity with related endogenous peptides (glucagon or GLP-1).

Injection site reactions

Injection site reactions have been reported in approximately 5.7% of subjects receiving exenatide in long term (26 weeks or longer) controlled clinical trials. These reactions have usually been mild and usually did not result in discontinuation of exenatide.

Spontaneous Data

General:

Common (≥1% and <10%): injection-site reactions.

Gastrointestinal disorders:

Uncommon (≥0.1% and <1%): abdominal distension, abdominal pain, eructation, constipation, flatulence. Rare (≥0.01% and <0.1%): acute pancreatitis. Very rare (<0.01%): Cases of ileus, ischaemic colitis and gut ischaemia have been reported.

Nervous System disorders:

Uncommon (≥0.1% and <1%): dysgeusia. Rare (≥0.01% and <0.1%): somnolence.

Investigations:

Rare (≥0.01% and <0.1%) INR increased with concomitant warfarin use, some reports associated with bleeding (see PRECAUTIONS and INTERACTIONS WITH OTHER MEDICINES).

Immune system disorder:

Very rare (<0.01%): anaphylactic reaction.

Skin and subcutaneous disorders

Rare (≥0.01% and <0.1%): angioedema, generalized pruritus and/or urticaria, macular or papular rash, alopecia.

Metabolism and nutritional disorders:

Rare (≥0.01% and <0.1%): dehydration, generally associated with nausea, vomiting, and/or diarrhoea, weight decreased (see PRECAUTIONS, Weight Loss).

Renal and urinary disorders:

Rare (>0.01% and <0.1%): acute renal failure, chronic renal failure, renal impairment, increased serum creatinine (see PRECAUTIONS).

Dosage and Administration

Exenatide therapy should be initiated at 5 мg exenatide per dose administered twice daily (BID) for at least one month in order to improve tolerability. The dose of BYETTA can then be increased to 10 мg BID to further improve glycaemic control. Doses higher than 10 µg BID are not recommended.

Exenatide can be administered at any time within the 60-minute period before the morning and evening meals (or before the two main meals of the day, approximately 6 hours or more apart). Exenatide should not be administered after a meal. If an injection is missed, the treatment should be continued with the next scheduled dose.

Each dose of BYETTA should be administered as a subcutaneous injection in the thigh, abdomen, or upper arm. Exenatide is not recommended to be administered by intravenous or intramuscular injection. Exenatide and basal insulin must be administered as two separate injections.

Exenatide is recommended for use in patients with type 2 diabetes mellitus who are already receiving metformin, a sulfonylurea, or both, or a basal insulin with metformin. When BYETTA is added to metformin therapy, the current dose of metformin can be continued as no increased risk of hypoglycaemia is anticipated, compared to metformin alone. When BYETTA is added to sulfonylurea therapy, a reduction in the dose of sulfonylurea may be considered to reduce the risk of hypoglycaemia (see PRECAUTIONS). When exenatide is used in combination with insulin, the dose of insulin should be evaluated. In patients at increased risk of hypoglycemia consider reducing the dose of insulin (see CLINICAL TRIALS).

The concurrent use of exenatide with prandial insulin has not been studied and cannot be recommended. Exenatide treatment should be ceased prior to commencing a basal bolus regimen.

Specific patient groups Gender, age, race or obesity

No dosage adjustment is necessary for gender, for age, for race or for obese patients (BMI >30 kg/m2) (see Pharmacokinetics).

Patients with renal impairment

No dosage adjustment is necessary in patients with mild renal impairment (creatinine clearance 50 to 80 mL/min) (see Pharmacokinetics).

In patients with moderate renal impairment (creatinine clearance: 30 to 50 mL/min), dose escalation from 5 мg to 10 мg should proceed conservatively (see PRECAUTIONS and Pharmacokinetics).

Exenatide should not be used in patients with end-stage renal disease or severe renal impairment (creatinine clearance <30 mL/min) (see CONTRAINDICATIONS and Pharmacokinetics).

Patients with hepatic impairment

Exenatide can be given to patients with hepatic impairment (see Pharmacokinetics).

Children and adolescents

Exenatide has not been studied in children and adolescents below 18 years.

Instructions for use and handling

Each BYETTA pen is for use by one person only. Instructions on how to use the pen are provided in the User Manual. The instructions for using the pen must be followed carefully.

Exenatide should not be used if particles appear or if the solution is cloudy and coloured.

Exenatide that has been frozen must not be used.

The patient should be advised to discard the needle after each injection. Used needles should be disposed of in appropriate needle bin and returned to pharmacists or given to diabetes nurse educators for disposal. The pen is stored without the needle attached. The cartridge must not be refilled.

Incompatibilities

Exenatide must not be mixed with other medicines.

Overdosage

In a clinical study of exenatide, three patients with type 2 diabetes each experienced a single overdose of 100 мg SC (10 times the maximum recommended dose). One of the three patients experienced severe hypoglycemia requiring parenteral glucose administration. The three patients recovered without complication.

In a spontaneously reported case of overdose, a patient was administered the total contents of an exenatide pen (approximately 300 µg) that had been transferred to a syringe. The patient subsequently experienced severe nausea and vomiting, which resolved within 24 hours. The patient did not experience hypoglycaemia or a decline in blood glucose.

Signs and symptoms of overdose may include severe nausea, severe vomiting, rapidly declining blood glucose concentrations, and hypoglycemia possibly requiring prolonged treatment. In the event of overdose, appropriate supportive treatment (possibly given parenterally) should be initiated according to the patient’s clinical signs and symptoms.

Presentation and Storage Conditions

BYETTA is supplied for subcutaneous injection as a sterile, preserved isotonic solution in a glass cartridge that has been assembled into a disposable pen-injector (pen). Two presentations of pre-filled pens are available, to deliver doses of either 5 µg or 10 µg. Each pre-filled pen will deliver 60 doses, providing 30 days of BID (twice daily) administration.

A BYETTA 5 µg pre-filled pen contains 60 doses of sterile, preserved solution (approximately 1.2 mL). Each dose contains 5 µg exenatide in 20 microlitres (0.25 mg synthetic exenatide per mL).

A BYETTA 10 µg pre-filled pen contains 60 doses of sterile, preserved solution (approximately 2.4 mL). Each dose contains 10 µg exenatide in 40 microlitres (0.25 mg synthetic exenatide per mL).

Pack size of 1 BYETTA pen.

Storage

Store at 2°C to 8°C. Refrigerate. Do not freeze. Protect from light.

Once in use the BYETTA pen should be kept below 25°C and away from direct heat and light.

The BYETTA pen should not be stored with the needle attached.

Shelf life for pen in use is 30 days. The pen should be discarded 30 days after use, even if some medicine remains in the pen.

Name and Address of the Sponsor

AstraZeneca Pty Ltd

ABN 54 009 682 311

Alma Road

NORTH RYDE NSW 2113

Poison Schedule of the Medicine

S4 (Prescription only medicine)

Date of First Inclusion in the Australian Register of Therapeutic Goods

13 June 2007

Date of Most Recent Amendment

2 March 2015

BYETTA® is a registered trademark of the AstraZeneca group of companies.

© AstraZeneca 2015