The following adverse reactions are discussed in other sections of the labeling:
- Severe acute exacerbations of Hepatitis [ see Boxed Warning, Warnings and Precautions]
- Nephrotoxicity [ see Boxed Warning, Warnings and Precautions ]
Clinical Trials Experience
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.
Clinical and laboratory evidence of exacerbations of hepatitis have occurred after discontinuation of treatment with HEPSERA.
Adverse reactions to HEPSERA identified from placebo-controlled and open label studies include the following: asthenia, headache, abdominal pain, diarrhea, nausea, dyspepsia, flatulence, increased creatinine, and hypophosphatemia.
The incidence of these adverse reactions in studies 437 and 438, where 522 patients with chronic hepatitis B and compensated liver disease received double-blind treatment with HEPSERA (n=294) or placebo (n=228) for 48 weeks is presented in Table 2. Patients who received open-label HEPSERA for up to 240 weeks in Study 438 reported adverse reactions similar in nature and severity to those reported in the first 48 weeks.
Table 2 Adverse Reactions (Grades 1–4) Reported in ≥3% of All HEPSERA-Treated Patients in Pooled Studies 437–438 Studies (0–48 Weeks)In these studies, the overall incidence of adverse reactions with HEPSERA was similar to that reported with placebo. The incidence of adverse reactions is derived from treatment-related events as identified by the study investigators.
No patients treated with HEPSERA developed a confirmed serum creatinine increase ≥0.5 mg/dL or confirmed phosphorus decrease ≤2 mg/dL from baseline by week 48. By week 96, 2% of HEPSERA-treated patients, by Kaplan-Meier estimate, had increases in serum creatinine ≥0.5 mg/dL from baseline (no placebo-controlled results were available for comparison beyond week 48). For patients who chose to continue HEPSERA for up to 240 weeks in Study 438, 4 of 125 patients (3%) had a confirmed increase of 0.5 mg/dL from baseline. The creatinine elevation resolved in 1 patient who permanently discontinued treatment and remained stable in 3 patients who continued treatment. For 65 patients who chose to continue HEPSERA for up to 240 weeks in Study 437, 6 had a confirmed increase in serum creatinine of ≥0.5 mg/dL from baseline with 2 patients discontinuing from the study due to the elevated serum creatinine concentration. See Adverse Reactions for changes in serum creatinine in patients with underlying renal insufficiency at baseline.
Special Risk Patients
Pre- and Post-Liver Transplantation Patients
Additional adverse reactions observed from an open-label study (study 435) in pre- and post- liver transplantation patients with chronic hepatitis B and lamivudine-resistant hepatitis B administered HEPSERA once daily for up to 203 weeks include: abnormal renal function, renal failure, vomiting, rash, and pruritus.
Changes in renal function occurred in pre-and post-liver transplantation patients with risk factors for renal dysfunction, including concomitant use of cyclosporine and tacrolimus, renal insufficiency at baseline, hypertension, diabetes, and on-study transplantation. Therefore, the contributory role of HEPSERA to these changes in renal function is difficult to assess.
Increases in serum creatinine ≥0.3 mg/dL from baseline were observed in 37% and 53% of pre-liver transplantation patients by weeks 48 and 96, respectively, by Kaplan-Meier estimates. Increases in serum creatinine ≥0.3 mg/dL from baseline were observed in 32% and 51% of post-liver transplantation patients by weeks 48 and 96, respectively, by Kaplan-Meier estimates. Serum phosphorus values <2 mg/dL were observed in 3/226 (1.3%) of pre-liver transplantation patients and in 6/241 (2.5%) of post-liver transplantation patients by last study visit. Four percent (19 of 467) of patients discontinued treatment with HEPSERA due to renal adverse events.
Assessment of adverse reactions is based on a placebo-controlled study (study 518) in which 173 pediatric patients aged 2 to <18 years with chronic hepatitis B and compensated liver disease received double-blind treatment with HEPSERA (n=115), or placebo (n=58) for 48 weeks [see Clinical Studies and Use In Specific Populations].
The safety profile of HEPSERA in patients ≥12 to <18 years of age (n=56) was similar to that observed in adults. No pediatric patients treated with HEPSERA developed a confirmed serum creatinine increase ≥ 0.5 mg/dL or confirmed phosphorus decrease to <2 mg/dL from baseline by Week 48.
In addition to adverse reaction reports from clinical trials, the following possible adverse reactions have also been identified during post-approval use of adefovir dipivoxil. Because these events have been reported voluntarily from a population of unknown size, estimates of frequency cannot be made.
Metabolism and Nutrition Disorders: hypophosphatemia
Musculoskeletal System and Connective Tissue Disorders: myopathy, osteomalacia (both associated with proximal renal tubulopathy)
Renal and Urinary Disorders: renal failure, proximal renal tubulopathy, Fanconi syndrome