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.

Adverse Reactions from Clinical Trials Experience in HIV-1 Infected Adults

  
More than 12,000 subjects have been treated with tenofovir disoproxil fumarate alone or in combination with other antiretroviral medicinal products for periods of 28 days to 215 weeks in clinical trials and expanded access programs. A total of 1,544 subjects have received tenofovir disoproxil fumarate 300 mg once daily in clinical trials; over 11,000 subjects have received tenofovir disoproxil fumarate in expanded access programs.   
The most common adverse reactions (incidence greater than or equal to 10%, Grades 2–4) identified from any of the 3 large controlled clinical trials include rash, diarrhea, headache, pain, depression, asthenia, and nausea. 

Clinical Trials in Treatment-Naïve HIV-1 Infected Adult Subjects

In Trial 903, 600 antiretroviral-naïve subjects received tenofovir disoproxil fumarate (N=299) or stavudine (d4T) (N=301) administered in combination with lamivudine (3TC) and efavirenz (EFV) for 144 weeks. The most common adverse reactions were mild to moderate gastrointestinal events and dizziness. Mild adverse reactions (Grade 1) were common with a similar incidence in both arms and included dizziness, diarrhea, and nausea. Table 4 provides the treatment-emergent adverse reactions (Grades 2–4) occurring in greater than or equal to 5% of subjects treated in any treatment group.

Laboratory Abnormalities:Table 5 provides a list of laboratory abnormalities (Grades 3–4) observed in Trial 903. With the exception of fasting cholesterol and fasting triglyceride elevations that were more common in the d4T group (40% and 9%) compared with the tenofovir disoproxil fumarate group (19% and 1%), respectively, laboratory abnormalities observed in this trial occurred with similar frequency in the tenofovir disoproxil fumarate and d4T treatment arms. 

Changes in Bone Mineral Density:In HIV-1 infected adult subjects in Trial 903, there was a significantly greater mean percentage decrease from baseline in BMD at the lumbar spine in subjects receiving tenofovir disoproxil fumarate + 3TC + EFV (−2.2% ± 3.9) compared with subjects receiving d4T + 3TC + EFV (−1.0% ± 4.6) through 144 weeks. Changes in BMD at the hip were similar between the two treatment groups (−2.8% ± 3.5 in the tenofovir disoproxil fumarate group vs. −2.4% ± 4.5 in the d4T group). In both groups, the majority of the reduction in BMD occurred in the first 24–48 weeks of the trial and this reduction was sustained through Week 144. Twenty-eight percent of tenofovir disoproxil fumarate-treated subjects vs. 21% of d4T-treated subjects lost at least 5% of BMD at the spine or 7% of BMD at the hip. Clinically relevant fractures (excluding fingers and toes) were reported in 4 subjects in the tenofovir disoproxil fumarate group and 6 subjects in the d4T group. In addition, there were significant increases in biochemical markers of bone metabolism (serum bone-specific alkaline phosphatase, serum osteocalcin, serum C telopeptide, and urinary N telopeptide) and higher serum parathyroid hormone levels and 1,25 Vitamin D levels in the tenofovir disoproxil fumarate group relative to the d4T group; however, except for bone-specific alkaline phosphatase, these changes resulted in values that remained within the normal range [see Warnings and Precautions (5.5)] . 

In Trial 934, 511 antiretroviral-naïve subjects received efavirenz (EFV) administered in combination with either emtricitabine (FTC) + tenofovir disoproxil fumarate (N=257) or zidovudine (AZT)/lamivudine (3TC) (N=254) for 144 weeks. The most common adverse reactions (incidence greater than or equal to 10%, all grades) included diarrhea, nausea, fatigue, headache, dizziness, depression, insomnia, abnormal dreams, and rash. Table 6 provides the treatment-emergent adverse reactions (Grades 2–4) occurring in greater than or equal to 5% of subjects treated in any treatment group.

Laboratory Abnormalities:Laboratory abnormalities observed in this trial were generally consistent with those seen in previous trials (Table 7). 

Clinical Trials in Treatment-Experienced HIV-1 Infected Adult Subjects

In Trial 907, the adverse reactions seen in HIV-1 infected treatment-experienced subjects were generally consistent with those seen in treatment-naïve subjects, including mild to moderate gastrointestinal events, such as nausea, diarrhea, vomiting, and flatulence. Less than 1% of subjects discontinued participation in the clinical trials due to gastrointestinal adverse reactions. Table 8 provides the treatment-emergent adverse reactions (Grades 2–4) occurring in greater than or equal to 3% of subjects treated in any treatment group.

Laboratory Abnormalities:Table 9 provides a list of Grade 3–4 laboratory abnormalities observed in Trial 907. Laboratory abnormalities occurred with similar frequency in the tenofovir disoproxil fumarate and placebo groups. 

Adverse Reactions from Clinical Trials Experience in HIV-1 Infected Pediatric Subjects 2 Years and Older

Assessment of adverse reactions is based on two randomized trials (Trials 352 and 321) in 184 HIV-1 infected pediatric subjects (2 years to less than 18 years of age) who received treatment with tenofovir disoproxil fumarate (N=93) or placebo/active comparator (N=91) in combination with other antiretroviral agents for 48 weeks [see Clinical Studies (14.3)] . The adverse reactions observed in subjects who received treatment with tenofovir disoproxil fumarate were consistent with those observed in clinical trials in adults. 

In Trial 352, 89 pediatric subjects (2 years to less than 12 years of age) received tenofovir disoproxil fumarate for a median exposure of 104 weeks. Of these, 4 subjects discontinued from the trial due to adverse reactions consistent with proximal renal tubulopathy. Three of these 4 subjects presented with hypophosphatemia and also had decreases in total body or spine BMD Z-score [see Warnings and Precautions (5.5)] . 

Changes in Bone Mineral Density:In Trial 321 (12 years to less than 18 years of age), the mean rate of BMD gain at Week 48 was less in the tenofovir disoproxil fumarate group compared to the placebo group. Six tenofovir disoproxil fumarate-treated subjects and one placebo-treated subject had significant (greater than 4%) lumbar spine BMD loss at Week 48. Changes from baseline BMD Z-scores were −0.341 for lumbar spine and −0.458 for total body in the 28 subjects who were treated with tenofovir disoproxil fumarate for 96 weeks. In Trial 352 (2 years to less than 12 years of age), the mean rate of BMD gain in lumbar spine at Week 48 was similar between the tenofovir disoproxil fumarate and the d4T or AZT treatment groups. Total body BMD gain was less in the tenofovir disoproxil fumarate group compared to the d4T or AZT treatment group. One tenofovir disoproxil fumarate-treated subject and none of the d4T- or AZT-treated subjects experienced significant (greater than 4%) lumbar spine BMD loss at Week 48. Changes from baseline in BMD Z-scores were −0.012 for lumbar spine and −0.338 for total body in the 64 subjects who were treated with tenofovir disoproxil fumarate for 96 weeks. In both trials, skeletal growth (height) appeared to be unaffected for the duration of the clinical trials [see Warnings and Precautions (5.5)] . 

Adverse Reactions from Clinical Trials Experience in HBV-Infected Adults

Clinical Trials in Adult Subjects with Chronic Hepatitis B and Compensated Liver Disease

In controlled clinical trials in 641 subjects with chronic hepatitis B (0102 and 0103), more subjects treated with tenofovir disoproxil fumarate during the 48-week double-blind period experienced nausea: 9% with tenofovir disoproxil fumarate versus 2% with HEPSERA ®. Other treatment-emergent adverse reactions reported in more than 5% of subjects treated with tenofovir disoproxil fumarate included: abdominal pain, diarrhea, headache, dizziness, fatigue, nasopharyngitis, back pain, and skin rash. 

In Trials 0102 and 0103, during the open-label phase of treatment with tenofovir disoproxil fumarate (weeks 48–384), 2% of subjects (13/585) experienced a confirmed increase in serum creatinine of 0.5 mg/dL from baseline. No significant change in the tolerability profile was observed with continued treatment for up to 384 weeks.

Laboratory Abnormalities:Table 10 provides a list of Grade 3–4 laboratory abnormalities through Week 48. Grades 3–4 laboratory abnormalities were similar in subjects continuing tenofovir disoproxil fumarate treatment for up to 384 weeks in these trials. 

The overall incidence of on-treatment ALT flares (defined as serum ALT greater than 2 × baseline and greater than 10 × ULN, with or without associated symptoms) was similar between tenofovir disoproxil fumarate (2.6%) and HEPSERA (2%). ALT flares generally occurred within the first 4 to 8 weeks of treatment and were accompanied by decreases in HBV DNA levels. No subject had evidence of decompensation. ALT flares typically resolved within 4 to 8 weeks without changes in study medication.

The adverse reactions observed in subjects with chronic hepatitis B and lamivudine resistance who received treatment with tenofovir disoproxil fumarate were consistent with those observed in other HBV clinical trials in adults.

Clinical Trials in Adult Subjects with Chronic Hepatitis B and Decompensated Liver Disease

In Trial 0108, a small randomized, double-blind, active-controlled trial, subjects with chronic HBV and decompensated liver disease received treatment with tenofovir disoproxil fumarate or other antiviral drugs for up to 48 weeks [see Clinical Studies (14.4)] . Among the 45 subjects receiving tenofovir disoproxil fumarate, the most frequently reported treatment-emergent adverse reactions of any severity were abdominal pain (22%), nausea (20%), insomnia (18%), pruritus (16%), vomiting (13%), dizziness (13%), and pyrexia (11%). Two of 45 (4%) subjects died through Week 48 of the trial due to progression of liver disease. Three of 45 (7%) subjects discontinued treatment due to an adverse event. Four of 45 (9%) subjects experienced a confirmed increase in serum creatinine of 0.5 mg/dL (1 subject also had a confirmed serum phosphorus less than 2 mg/dL through Week 48). Three of these subjects (each of whom had a Child-Pugh score greater than or equal to 10 and MELD score greater than or equal to 14 at entry) developed renal failure. Because both tenofovir disoproxil fumarate and decompensated liver disease may have an impact on renal function, the contribution of tenofovir disoproxil fumarate to renal impairment in this population is difficult to ascertain. 

One of 45 subjects experienced an on-treatment hepatic flare during the 48-week trial.

Adverse Reactions from Clinical Trials Experience in HBV-Infected Pediatric Subjects 2 Years and Older

Assessment of adverse reactions in pediatric subjects infected with chronic HBV is based on two randomized trials: Trial GS-US-174-0115 in 106 subjects (12 years to less than 18 years of age) receiving treatment with tenofovir disoproxil fumarate (N=52) or placebo (N=54) for 72 weeks and Trial GS-US-174-0144 in 89 subjects (2 years to less than 12 years of age) receiving treatment with tenofovir disoproxil fumarate (N=60) or placebo (N=29) for 48 weeks [see Clinical Studies (14.5)] . The adverse reactions observed in pediatric subjects who received treatment with tenofovir disoproxil fumarate were consistent with those observed in clinical trials of tenofovir disoproxil fumarate in adults. 

In Trial 115 (12 years to less than 18 years of age) and Trial 144 (2 years to less than 12 years of age), both the tenofovir disoproxil fumarate and placebo treatment arms experienced an overall increase in mean lumbar spine and total body BMD over 72 and 48 weeks, respectively, as expected for a pediatric population (Table 11). In Trial 115, the mean percentage BMD gains from baseline to Week 72 in lumbar spine and total body BMD in tenofovir disoproxil fumarate-treated subjects were less than the mean percentage BMD gains observed in placebo-treated subjects (Table 11).Three subjects (6%) in the tenofovir disoproxil fumarate group and two subjects (4%) in the placebo group had significant (greater than or equal to 4%) lumbar spine BMD loss at Week 72. In Trial 144 (2 years to less than 12 years of age), mean percentage BMD gains from baseline to Week 48 in lumbar spine and total body BMD in tenofovir disoproxil fumarate-treated subjects were less than the mean percentage BMD gains observed in placebo-treated subjects. At Week 48, the cumulative percentage of subjects with greater than or equal to 4% decreases in spine or whole body BMD was numerically higher for subjects in the TDF group compared with the placebo group (Table 11). As observed in pediatric studies of HIV-infected subjects, normal skeletal growth (height) was not affected for the duration of the clinical trial [see Warnings and Precautions (5.5)] . 

The effects of tenofovir disoproxil fumarate-associated changes in BMD and biochemical markers on long-term bone health and future fracture risk in pediatric patients 2 years and older are unknown. The long-term effect of lower spine and total body BMD on skeletal growth in pediatric patients 2 years and older, and in particular, the effects of long-duration exposure in younger children is unknown [see Warnings and Precautions ( 5.5)].