Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Hypoglycemia
Table 1 summarizes the incidence and rate of hypoglycemia with exenatide in six placebo-controlled clinical trials.
Table 1: Incidence (%) and Rate of Hypoglycemia when Exenatide was used as Monotherapy or with Concomitant Antidiabetic Therapy in Six Placebo-Controlled Clinical Trials*
Immunogenicity
Antibodies were assessed in 90% of subjects in the 30-week, 24-week, and 16-week studies of exenatide. In the 30-week controlled trials of exenatide add-on to metformin and/or sulfonylurea, antibodies were assessed at 2- to 6-week intervals. The mean antibody titer peaked at Week 6 and was reduced by 55% by Week 30. Three hundred and sixty patients (38%) had low titer antibodies (< 625) to exenatide at 30 weeks. The level of glycemic control (HbA1c) in these patients was generally comparable to that observed in the 534 patients (56%) without antibody titers. An additional 59 patients (6%) had higher titer antibodies (≥ 625) at 30 weeks. Of these patients, 32 (3% overall) had an attenuated glycemic response to exenatide; the remaining 27 (3% overall) had a glycemic response comparable to that of patients without antibodies.
In the 16-week trial of exenatide add-on to thiazolidinediones, with or without metformin, 36 patients (31%) had low titer antibodies to exenatide at 16 weeks. The level of glycemic control in these patients was generally comparable to that observed in the 69 patients (60%) without antibody titer. An additional 10 patients (9%) had higher titer antibodies at 16 weeks. Of these patients, 4 (4% overall) had an attenuated glycemic response to exenatide; the remaining 6 (5% overall) had a glycemic response comparable to that of patients without antibodies.
In the 24-week trial of exenatide used as monotherapy, 40 patients (28%) had low titer antibodies to exenatide at 24 weeks. The level of glycemic control in these patients was generally comparable to that observed in the 101 patients (70%) without antibody titers. An additional 3 patients (2%) had higher titer antibodies at 24 weeks. Of these patients, 1 (1% overall) had an attenuated glycemic response to exenatide; the remaining 2 (1% overall) had a glycemic response comparable to that of patients without antibodies.
Antibodies to exenatide were not assessed in the 30-week placebo-controlled trial of exenatide used in combination with insulin glargine.
In the 30-week comparator-controlled trial of exenatide used in combination with insulin glargine and metformin, 60 patients (20%) had low titer antibodies to exenatide at 30 weeks. The level of glycemic control in these patients was generally comparable to that observed in the 234 patients (77%) without antibody titers. An additional 10 patients (3%) had higher titer antibodies at 30 weeks. Of these patients, 2 (1% overall) had an attenuated glycemic response to exenatide; the remaining 8 (3% overall) had a glycemic response comparable to that of patients without antibodies.
Two hundred and ten patients with antibodies to exenatide in the exenatide clinical trials were tested for the presence of cross-reactive antibodies to GLP-1 and/or glucagon. No treatment-emergent cross-reactive antibodies were observed across the range of titers.
For the 24-week placebo-controlled study of exenatide used as a monotherapy, Table 2 summarizes adverse reactions (excluding hypoglycemia) occurring with an incidence ≥ 2% and occurring more frequently in exenatide-treated patients compared with placebo-treated patients.
Table 2: Treatment-Emergent Adverse Reactions ≥ 2% Incidence with Exenatide used as Monotherapy (excluding Hypoglycemia)*
Adverse reactions reported in ≥ 1.0% to < 2.0% of patients receiving exenatide and reported more frequently than with placebo included decreased appetite, diarrhea and dizziness. The most frequently reported adverse reaction associated with exenatide, nausea, occurred in a dose-dependent fashion.
Two of the 155 patients treated with exenatide withdrew due to adverse reactions of headache and nausea. No placebo-treated patients withdrew due to adverse reactions.
Cholelithiasis and cholecystitis
In a clinical study with exenatide, 1.9% of exenatide-treated patients and 1.4% of placebo-treated patients reported an acute event of gallbladder disease, such as cholelithiasis or cholecystitis.
In the three 30-week controlled trials of exenatide add-on to metformin and/or sulfonylurea, adverse reactions (excluding hypoglycemia) with an incidence ≥ 2% and occurring more frequently in exenatide-treated patients compared with placebo-treated patients are summarized in Table 3.
Table 3: Treatment-Emergent Adverse Reactions ≥ 2% Incidence and Greater Incidence with Exenatide Treatment used with Metformin and/or a Sulfonylurea (excluding Hypoglycemia)*
Adverse reactions reported in ≥ 1.0% to < 2.0% of patients receiving exenatide and reported more frequently than with placebo included decreased appetite. Nausea was the most frequently reported adverse reaction and occurred in a dose-dependent fashion. With continued therapy, the frequency and severity decreased over time in most of the patients who initially experienced nausea. Patients in the long-term uncontrolled open-label extension studies at 52 weeks reported no new types of adverse reactions than those observed in the 30-week controlled trials.
The most common adverse reactions leading to withdrawal for exenatide-treated patients were nausea (3% of patients) and vomiting (1%). For placebo-treated patients, < 1% withdrew due to nausea and none due to vomiting.
Add-On to Thiazolidinedione with or without Metformin
For the 16-week placebo-controlled study of exenatide add-on to a thiazolidinedione, with or without metformin, Table 4 summarizes the adverse reactions (excluding hypoglycemia) with an incidence of ≥ 2% and occurring more frequently in exenatide-treated patients compared with placebo-treated patients.
Table 4: Treatment-Emergent Adverse Reactions ≥ 2% Incidence with Exenatide used with a Thiazolidinedione (TZD), with or without Metformin (MET) (excluding Hypoglycemia)*
Adverse reactions reported in ≥ 1.0% to < 2.0% of patients receiving exenatide and reported more frequently than with placebo included decreased appetite. Chills (n=4) and injection-site reactions (n=2) occurred only in exenatide-treated patients. The two patients who reported an injection-site reaction had high titers of antibodies to exenatide. Two serious adverse events (chest pain and chronic hypersensitivity pneumonitis) were reported in the exenatide arm. No serious adverse events were reported in the placebo arm.
The most common adverse reactions leading to withdrawal for exenatide-treated patients were nausea (9%) and vomiting (5%). For placebo-treated patients, < 1% withdrew due to nausea.
Add-On to Insulin Glargine with or without Metformin and/or Thiazolidinedione (Placebo-Controlled)
For the 30-week placebo-controlled study of exenatide as add-on to insulin glargine with or without oral antihyperglycemic medications, Table 5 summarizes adverse reactions (excluding hypoglycemia) occurring with an incidence ≥ 2% and occurring more frequently in exenatide-treated patients compared with placebo-treated patients.
Table 5: Treatment-Emergent Adverse Reactions ≥ 2% Incidence with Exenatide used with Insulin Glargine with or without Oral Antihyperglycemic Medications (excluding Hypoglycemia)*
The most frequently reported adverse reactions leading to withdrawal for exenatide-treated patients were nausea (5.1%) and vomiting (2.9%). No placebo-treated patients withdrew due to nausea or vomiting.