Truvada®, a combination of EMTRIVA® and VIREAD®, is indicated in combination with other antiretroviral agents (such as non-nucleoside reverse transcriptase inhibitors or protease inhibitors) for the treatment of HIV-1 infection in adults and pediatric patients 12 years of age and older.
The following points should be considered when initiating therapy with Truvada for the treatment of HIV-1 infection:
- It is not recommended that Truvada be used as a component of a triple nucleoside regimen.
- Truvada should not be coadministered with ATRIPLA®, EMTRIVA, VIREAD or lamivudine-containing products [See Warnings and Precautions (5.4)].
- In treatment experienced patients, the use of Truvada should be guided by laboratory testing and treatment history [See Clinical Pharmacology (12.4)].
Truvada Dosage and Administration
Recommended Dose
The dose of Truvada for adults and pediatric patients 12 years of age and older with body weight greater than or equal to 35 kg (greater than or equal to 77 lb) is one tablet (containing 200 mg of emtricitabine and 300 mg of tenofovir disoproxil fumarate) once daily taken orally with or without food.
Dose Adjustment for Renal Impairment
Significantly increased drug exposures occurred when EMTRIVA or VIREAD were administered to subjects with moderate to severe renal impairment [see EMTRIVA or VIREAD Package Insert]. Therefore, the dosing interval of Truvada should be adjusted in patients with baseline creatinine clearance 30–49 mL/min using the recommendations in Table 1. These dosing interval recommendations are based on modeling of single-dose pharmacokinetic data in non-HIV infected subjects. The safety and effectiveness of these dosing interval adjustment recommendations have not been clinically evaluated in patients with moderate renal impairment, therefore clinical response to treatment and renal function should be closely monitored in these patients [See Warnings and Precautions (5.3)].
No dose adjustment is necessary for patients with mild renal impairment (creatinine clearance 50–80 mL/min). Routine monitoring of calculated creatinine clearance and serum phosphorus should be performed in patients with mild renal impairment [See Warnings and Precautions (5.3)].
Table 1 Dosage Adjustment for Patients with Altered Creatinine Clearance
|
Creatinine Clearance (mL/min) |
|---|
|
≥50 |
30–49 |
<30
(Including Patients Requiring Hemodialysis) |
|---|
|
| Recommended Dosing Interval |
Every 24 hours |
Every 48 hours |
Truvada should not be administered. |
No data are available to make dose recommendations in pediatric patients 12 years of age and older with renal impairment.
Dosage Forms and Strengths
Truvada is available as tablets. Each tablet contains 200 mg of emtricitabine and 300 mg of tenofovir disoproxil fumarate (which is equivalent to 245 mg of tenofovir disoproxil). The tablets are blue, capsule-shaped, film-coated, debossed with "GILEAD" on one side and with "701" on the other side.
Contraindications
None.
Warnings and Precautions
Lactic Acidosis/Severe Hepatomegaly with Steatosis
Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs, including VIREAD, a component of Truvada, in combination with other antiretrovirals. A majority of these cases have been in women. Obesity and prolonged nucleoside exposure may be risk factors. Particular caution should be exercised when administering nucleoside analogs to any patient with known risk factors for liver disease; however, cases have also been reported in patients with no known risk factors. Treatment with Truvada should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations).
Patients Coinfected with HIV-1 and HBV
It is recommended that all patients with HIV-1 be tested for the presence of chronic hepatitis B virus (HBV) before initiating antiretroviral therapy. Truvada is not approved for the treatment of chronic HBV infection and the safety and efficacy of Truvada have not been established in patients coinfected with HBV and HIV-1. Severe acute exacerbations of hepatitis B have been reported in patients who are coinfected with HBV and HIV-1 and have discontinued Truvada. In some patients infected with HBV and treated with EMTRIVA, the exacerbations of hepatitis B were associated with liver decompensation and liver failure. Patients who are coinfected with HIV-1 and HBV should be closely monitored with both clinical and laboratory follow up for at least several months after stopping treatment with Truvada. If appropriate, initiation of anti-hepatitis B therapy may be warranted.
New Onset or Worsening Renal Impairment
Emtricitabine and tenofovir are principally eliminated by the kidney. Renal impairment, including cases of acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), has been reported with the use of VIREAD [See Adverse Reactions (6.2)].
It is recommended that creatinine clearance be calculated in all patients prior to initiating therapy and as clinically appropriate during therapy with Truvada. Routine monitoring of calculated creatinine clearance and serum phosphorus should be performed in patients at risk for renal impairment, including patients who have previously experienced renal events while receiving HEPSERA.
Dosing interval adjustment of Truvada and close monitoring of renal function are recommended in all patients with creatinine clearance 30–49 mL/min, [See Dosage and Administration (2.2)]. No safety or efficacy data are available in patients with renal impairment who received Truvada using these dosing guidelines, so the potential benefit of Truvada therapy should be assessed against the potential risk of renal toxicity. Truvada should not be administered to patients with creatinine clearance below 30 mL/min or patients requiring hemodialysis.
Truvada should be avoided with concurrent or recent use of a nephrotoxic agent.
Coadministration with Other Products
Truvada is a fixed-dose combination of emtricitabine and tenofovir disoproxil fumarate. Truvada should not be coadministered with ATRIPLA, EMTRIVA, or VIREAD. Due to similarities between emtricitabine and lamivudine, Truvada should not be coadministered with other drugs containing lamivudine, including Combivir (lamivudine/zidovudine), Epivir or Epivir-HBV (lamivudine), Epzicom (abacavir sulfate/lamivudine), or Trizivir (abacavir sulfate/lamivudine/zidovudine).
Truvada should not be administered with HEPSERA® (adefovir dipivoxil).
Decreases in Bone Mineral Density
Assessment of bone mineral density (BMD) should be considered for HIV-1 infected adults and pediatric patients 12 years of age and older who have a history of pathologic bone fracture or other risk factors for osteoporosis or bone loss. Although the effect of supplementation with calcium and vitamin D was not studied, such supplementation may be beneficial for all patients. If bone abnormalities are suspected then appropriate consultation should be obtained.
Tenofovir Disoproxil Fumarate: In a 144-week trial of treatment-naive adult subjects, decreases in BMD were seen at the lumbar spine and hip in both arms of the trial. At Week 144, there was a significantly greater mean percentage decrease from baseline in BMD at the lumbar spine in subjects receiving VIREAD + lamivudine + efavirenz compared with subjects receiving stavudine + lamivudine + efavirenz. Changes in BMD at the hip were similar between the two treatment groups. 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 144 weeks. Twenty-eight percent of VIREAD-treated subjects vs. 21% of the comparator 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 VIREAD group and 6 subjects in the comparator group. Tenofovir disoproxil fumarate was associated with significant increases in biochemical markers of bone metabolism (serum bone-specific alkaline phosphatase, serum osteocalcin, serum C-telopeptide, and urinary N-telopeptide), suggesting increased bone turnover. Serum parathyroid hormone levels and 1,25 Vitamin D levels were also higher in subjects receiving VIREAD.
In a clinical trial of HIV-1 infected pediatric subjects 12 years of age and older (Study 321), bone effects were similar to adult subjects. Under normal circumstances BMD increases rapidly in this age group. In this trial, the mean rate of bone gain was less in the VIREAD-treated group compared to the placebo group. Six VIREAD treated subjects and one placebo treated subject had significant (greater than 4%) lumbar spine BMD loss in 48 weeks. Among 28 subjects receiving 96 weeks of VIREAD, Z-scores declined by -0.341 for lumbar spine and -0.458 for total body. Skeletal growth (height) appeared to be unaffected. Markers of bone turnover in VIREAD-treated pediatric subjects 12 years of age and older suggest increased bone turnover, consistent with the effects observed in adults.
The effects of VIREAD-associated changes in BMD and biochemical markers on long-term bone health and future fracture risk are unknown. For additional information, please consult the VIREAD prescribing information.
Cases of osteomalacia (associated with proximal renal tubulopathy and which may contribute to fractures) have been reported in association with the use of VIREAD [See Adverse Reactions (6.2)].
Fat Redistribution
Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.
Immune Reconstitution Syndrome
Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including Truvada. During the initial phase of combination antiretroviral treatment, patients whose immune system responds may develop an inflammatory response to indolent or residual opportunistic infections [such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia (PCP), or tuberculosis], which may necessitate further evaluation and treatment.
Early Virologic Failure
Clinical trials in HIV-infected subjects have demonstrated that certain regimens that only contain three nucleoside reverse transcriptase inhibitors (NRTI) are generally less effective than triple drug regimens containing two NRTIs in combination with either a non-nucleoside reverse transcriptase inhibitor or a HIV-1 protease inhibitor. In particular, early virological failure and high rates of resistance substitutions have been reported. Triple nucleoside regimens should therefore be used with caution. Patients on a therapy utilizing a triple nucleoside-only regimen should be carefully monitored and considered for treatment modification.
Adverse Reactions
The following adverse reactions are discussed in other sections of the labeling:
- Lactic Acidosis/Severe Hepatomegaly with Steatosis [See Boxed Warning, Warnings and Precautions (5.1)].
- Severe Acute Exacerbations of hepatitis B [See Boxed Warning, Warnings and Precautions (5.2)].
- New Onset or Worsening Renal Impairment [See Warnings and Precautions (5.3)].
- Decreases in Bone Mineral Density [See Warnings and Precautions (5.5)].
- Immune Reconstitution Syndrome [See Warnings and Precautions (5.7)].
Adverse Reactions from 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 Trials in Adult Subjects
The most common adverse reactions (incidence greater than or equal to 10%, any severity) occurring in Study 934, an active-controlled clinical trial of efavirenz, emtricitabine, and tenofovir disoproxil fumarate, include diarrhea, nausea, fatigue, headache, dizziness, depression, insomnia, abnormal dreams, and rash. See also Table 2 for the frequency of treatment-emergent adverse reactions (Grade 2–4) occurring in greater than or equal to 5% of subjects treated with efavirenz, emtricitabine, and tenofovir disoproxil fumarate in this trial.
Skin discoloration, manifested by hyperpigmentation on the palms and/or soles was generally mild and asymptomatic. The mechanism and clinical significance are unknown.
Study 934 - Treatment Emergent Adverse Reactions: In Study 934, 511 antiretroviral-naive subjects received either VIREAD + EMTRIVA administered in combination with efavirenz (N=257) or zidovudine/lamivudine administered in combination with efavirenz (N=254). Adverse reactions observed in this trial were generally consistent with those seen in other trials in treatment-experienced or treatment-naive subjects receiving VIREAD and/or EMTRIVA (Table 2).
Table 2 Selected Treatment-Emergent Adverse Reactions (Grades 2–4) Reported in ≥5% in Any Treatment Group in Study 934 (0–144 Weeks)
|
FTC + TDF + EFV |
AZT/3TC + EFV |
|---|
|
N=257 |
N=254 |
|---|
|
| Gastrointestinal Disorder |
|
|
| Diarrhea |
9% |
5% |
| Nausea |
9% |
7% |
| Vomiting |
2% |
5% |
| General Disorders and Administration Site Condition |
|
|
| Fatigue |
9% |
8% |
| Infections and Infestations |
|
|
| Sinusitis |
8% |
4% |
| Upper respiratory tract infections |
8% |
5% |
| Nasopharyngitis |
5% |
3% |
| Nervous System Disorders |
|
|
| Headache |
6% |
5% |
| Dizziness |
8% |
7% |
| Psychiatric Disorders |
|
|
| Depression |
9% |
7% |
| Insomnia |
5% |
7% |
| Skin and Subcutaneous Tissue Disorders |
|
|
| Rash event |
7% |
9% |
Laboratory Abnormalities: Laboratory abnormalities observed in this trial were generally consistent with those seen in other trials of VIREAD and/or EMTRIVA (Table 3).
Table 3 Significant Laboratory Abnormalities Reported in ≥1% of Subjects in Any Treatment Group in Study 934 (0–144 Weeks)
|
FTC + TDF + EFV |
AZT/3TC + EFV |
|---|
|
N=257 |
N=254 |
|---|
|
| Any ≥ Grade 3 Laboratory Abnormality |
30% |
26% |
| Fasting Cholesterol (>240 mg/dL) |
22% |
24% |
Creatine Kinase
(M: >990 U/L)
(F: >845 U/L) |
9% |
7% |
| Serum Amylase (>175 U/L) |
8% |
4% |
| Alkaline Phosphatase (>550 U/L) |
1% |
0% |
AST
(M: >180 U/L)
(F: >170 U/L) |
3% |
3% |
ALT
(M: >215 U/L)
(F: >170 U/L) |
2% |
3% |
| Hemoglobin (<8.0 mg/dL) |
0% |
4% |
| Hyperglycemia (>250 mg/dL) |
2% |
1% |
| Hematuria (>75 RBC/HPF) |
3% |
2% |
| Glycosuria (≥3+) |
<1% |
1% |
| Neutrophils (<750/mm3) |
3% |
5% |
| Fasting Triglycerides (>750 mg/dL) |
4% |
2% |
In addition to the events described above for Study 934, other adverse reactions that occurred in at least 5% of subjects receiving EMTRIVA or VIREAD with other antiretroviral agents in clinical trials include anxiety, arthralgia, increased cough, dyspepsia, fever, myalgia, pain, abdominal pain, back pain, paresthesia, peripheral neuropathy (including peripheral neuritis and neuropathy), pneumonia, and rhinitis.
In addition to the laboratory abnormalities described above for Study 934, Grade 3/4 laboratory abnormalities of increased bilirubin (>2.5 × ULN), increased pancreatic amylase (>2.0 × ULN), increased or decreased serum glucose (<40 or >250 mg/dL), and increased serum lipase (>2.0 × ULN) occurred in up to 3% of subjects treated with EMTRIVA or VIREAD with other antiretroviral agents in clinical trials.
Clinical Trials in Pediatric Subjects 12 Years of Age and Older
Emtricitabine: In addition to the adverse reactions reported in adults, anemia and hyperpigmentation were observed in 7% and 32%, respectively, of pediatric subjects (3 months to less than 18 years of age) who received treatment with EMTRIVA in the larger of two open-label, uncontrolled pediatric trials (N=116). For additional information, please consult the EMTRIVA prescribing information.
Tenofovir Disoproxil Fumarate: In a pediatric clinical trial conducted in subjects 12 to less than 18 years of age, the adverse reactions observed in pediatric subjects who received treatment with VIREAD were consistent with those observed in clinical trials of VIREAD in adults [See Warnings and Precautions (5.5)].
Postmarketing Experience
The following adverse reactions have been identified during postapproval use of VIREAD. No additional adverse reactions have been identified during postapproval use of EMTRIVA. Because postmarketing reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Immune System Disorders
allergic reaction, including angioedema
Metabolism and Nutrition Disorders
lactic acidosis, hypokalemia, hypophosphatemia
Respiratory, Thoracic, and Mediastinal Disorders
dyspnea
Gastrointestinal Disorders
pancreatitis, increased amylase, abdominal pain
Hepatobiliary Disorders
hepatic steatosis, hepatitis, increased liver enzymes (most commonly AST, ALT gamma GT)
Skin and Subcutaneous Tissue Disorders
rash
Musculoskeletal and Connective Tissue Disorders
rhabdomyolysis, osteomalacia (manifested as bone pain and which may contribute to fractures), muscular weakness, myopathy
Renal and Urinary Disorders
acute renal failure, renal failure, acute tubular necrosis, Fanconi syndrome, proximal renal tubulopathy, interstitial nephritis (including acute cases), nephrogenic diabetes insipidus, renal insufficiency, increased creatinine, proteinuria, polyuria
General Disorders and Administration Site Conditions
asthenia
The following adverse reactions, listed under the body system headings above, may occur as a consequence of proximal renal tubulopathy: rhabdomyolysis, osteomalacia, hypokalemia, muscular weakness, myopathy, hypophosphatemia.
Drug Interactions
No drug interaction trials have been conducted using Truvada tablets. Drug interaction trials have been conducted with emtricitabine and tenofovir disoproxil fumarate, the components of Truvada. This section describes clinically relevant drug interactions observed with emtricitabine and tenofovir disoproxil fumarate [See Clinical Pharmacology (12.3)].
Didanosine
Coadministration of Truvada and didanosine should be undertaken with caution and patients receiving this combination should be monitored closely for didanosine-associated adverse reactions. Didanosine should be discontinued in patients who develop didanosine-associated adverse reactions.
When tenofovir disoproxil fumarate was administered with didanosine the Cmax and AUC of didanosine administered as either the buffered or enteric-coated formulation increased significantly [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Higher didanosine concentrations could potentiate didanosine-associated adverse reactions, including pancreatitis, and neuropathy. Suppression of CD4+ cell counts has been observed in patients receiving tenofovir DF with didanosine 400 mg daily.
In patients weighing greater than 60 kg, the didanosine dose should be reduced to 250 mg when it is coadministered with Truvada. Data are not available to recommend a dose adjustment of didanosine for adult or pediatric patients weighing less than 60 kg. When coadministered, Truvada and Videx EC may be taken under fasted conditions or with a light meal (less than 400 kcal, 20% fat). Coadministration of didanosine buffered tablet formulation with Truvada should be under fasted conditions.
Atazanavir
Atazanavir has been shown to increase tenofovir concentrations [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Patients receiving atazanavir and Truvada should be monitored for Truvada-associated adverse reactions. Truvada should be discontinued in patients who develop Truvada-associated adverse reactions.
Tenofovir decreases the AUC and Cmin of atazanavir [See Clinical Pharmacology (12.3)]. When coadministered with Truvada, it is recommended that atazanavir 300 mg is given with ritonavir 100 mg. Atazanavir without ritonavir should not be coadministered with Truvada.
Lopinavir/Ritonavir
Lopinavir/ritonavir has been shown to increase tenofovir concentrations [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Patients receiving lopinavir/ritonavir and Truvada should be monitored for Truvada-associated adverse reactions. Truvada should be discontinued in patients who develop Truvada-associated adverse reactions.
Drugs Affecting Renal Function
Emtricitabine and tenofovir are primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion [See Clinical Pharmacology (12.3)]. No drug-drug interactions due to competition for renal excretion have been observed; however, coadministration of Truvada with drugs that are eliminated by active tubular secretion may increase concentrations of emtricitabine, tenofovir, and/or the coadministered drug. Some examples include, but are not limited to acyclovir, adefovir dipivoxil, cidofovir, ganciclovir, valacyclovir, and valganciclovir. Drugs that decrease renal function may increase concentrations of emtricitabine and/or tenofovir.
USE IN SPECIFIC POPULATIONS
Pregnancy
Pregnancy Category B
Emtricitabine: The incidence of fetal variations and malformations was not increased in embryofetal toxicity studies performed with emtricitabine in mice at exposures (AUC) approximately 60-fold higher and in rabbits at approximately 120-fold higher than human exposures at the recommended daily dose.
Tenofovir Disoproxil Fumarate: Reproduction studies have been performed in rats and rabbits at doses up to 14 and 19 times the human dose based on body surface area comparisons and revealed no evidence of impaired fertility or harm to the fetus due to tenofovir.
There are, however, no adequate and well-controlled trials in pregnant women. Because animal reproduction studies are not always predictive of human response, Truvada should be used during pregnancy only if clearly needed.
Antiretroviral Pregnancy Registry: To monitor fetal outcomes of pregnant women exposed to Truvada, an Antiretroviral Pregnancy Registry has been established. Healthcare providers are encouraged to register patients by calling 1-800-258-4263.
Nursing Mothers
Nursing Mothers: The Centers for Disease Control and Prevention recommend that HIV-1 infected mothers not breast-feed their infants to avoid risking postnatal transmission of HIV-1. Studies in rats have demonstrated that tenofovir is secreted in milk. It is not known whether tenofovir is excreted in human milk. It is not known whether emtricitabine is excreted in human milk. Because of both the potential for HIV-1 transmission and the potential for serious adverse reactions in nursing infants, mothers should be instructed not to breast-feed if they are receiving Truvada.
Pediatric Use
Truvada should only be administered to pediatric patients 12 years of age and older with body weight greater than or equal to 35 kg (greater than or equal to 77 lb) because it is a fixed-dose combination tablet containing a component, VIREAD, for which safety and efficacy have not been established in pediatric patients less than 12 years of age or weighing less than 35 kg (less than 77 lb) [See Warnings and Precautions (5.5), Adverse Reactions (6.1) and Clinical Pharmacology (12.3)].
Geriatric Use
Clinical trials of EMTRIVA or VIREAD did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for the elderly patients should be cautious, keeping in mind the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Patients with Impaired Renal Function
It is recommended that the dosing interval for Truvada be modified in patients with creatinine clearance 30–49 mL/min. Truvada should not be used in patients with creatinine clearance below 30 mL/min and in patients with end-stage renal disease requiring dialysis [See Dosage and Administration (2.2)].
Overdosage
If overdose occurs the patient must be monitored for evidence of toxicity, and standard supportive treatment applied as necessary.
Emtricitabine: Limited clinical experience is available at doses higher than the therapeutic dose of EMTRIVA. In one clinical pharmacology trials single doses of emtricitabine 1200 mg were administered to 11 subjects. No severe adverse reactions were reported.
Hemodialysis treatment removes approximately 30% of the emtricitabine dose over a 3-hour dialysis period starting within 1.5 hours of emtricitabine dosing (blood flow rate of 400 mL/min and a dialysate flow rate of 600 mL/min). It is not known whether emtricitabine can be removed by peritoneal dialysis.
Tenofovir Disoproxil Fumarate: Limited clinical experience at doses higher than the therapeutic dose of VIREAD 300 mg is available. In one trial, 600 mg tenofovir disoproxil fumarate was administered to 8 subjects orally for 28 days, and no severe adverse reactions were reported. The effects of higher doses are not known.
Tenofovir is efficiently removed by hemodialysis with an extraction coefficient of approximately 54%. Following a single 300 mg dose of VIREAD, a four-hour hemodialysis session removed approximately 10% of the administered tenofovir dose.
Truvada Description
Truvada tablets are fixed dose combination tablets containing emtricitabine and tenofovir disoproxil fumarate. EMTRIVA is the brand name for emtricitabine, a synthetic nucleoside analog of cytidine. Tenofovir disoproxil fumarate (tenofovir DF) is converted in vivo to tenofovir, an acyclic nucleoside phosphonate (nucleotide) analog of adenosine 5'-monophosphate. Both emtricitabine and tenofovir exhibit inhibitory activity against HIV-1 reverse transcriptase.
Emtricitabine: The chemical name of emtricitabine is 5-fluoro-1-(2R,5S)-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine. Emtricitabine is the (-) enantiomer of a thio analog of cytidine, which differs from other cytidine analogs in that it has a fluorine in the 5-position.
It has a molecular formula of C8H10FN3O3S and a molecular weight of 247.24. It has the following structural formula:
Emtricitabine is a white to off-white crystalline powder with a solubility of approximately 112 mg/mL in water at 25 °C. The partition coefficient (log p) for emtricitabine is -0.43 and the pKa is 2.65.
Tenofovir Disoproxil Fumarate: Tenofovir disoproxil fumarate is a fumaric acid salt of the bis-isopropoxycarbonyloxymethyl ester derivative of tenofovir. The chemical name of tenofovir disoproxil fumarate is 9-[(R)-2 [[bis[[(isopropoxycarbonyl)oxy]- methoxy]phosphinyl]methoxy]propyl]adenine fumarate (1:1). It has a molecular formula of C19H30N5O10P • C4H4O4 and a molecular weight of 635.52. It has the following structural formula:
Tenofovir disoproxil fumarate is a white to off-white crystalline powder with a solubility of 13.4 mg/mL in water at 25 °C. The partition coefficient (log p) for tenofovir disoproxil is 1.25 and the pKa is 3.75. All dosages are expressed in terms of tenofovir disoproxil fumarate except where otherwise noted.
Truvada tablets are for oral administration. Each film-coated tablet contains 200 mg of emtricitabine and 300 mg of tenofovir disoproxil fumarate, (which is equivalent to 245 mg of tenofovir disoproxil), as active ingredients. The tablets also include the following inactive ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and pregelatinized starch (gluten free). The tablets are coated with Opadry II Blue Y-30-10701, which contains FD&C Blue #2 aluminum lake, hydroxypropyl methylcellulose 2910, lactose monohydrate, titanium dioxide, and triacetin.
Truvada - Clinical Pharmacology
For additional information on Mechanism of Action, Antiviral Activity, Resistance and Cross Resistance, please consult the EMTRIVA and VIREAD prescribing information.
Mechanism of Action
Truvada is a fixed-dose combination of antiviral drugs emtricitabine and tenofovir disoproxil fumarate. [See Clinical Pharmacology (12.4)].
Pharmacokinetics
Truvada: One Truvada tablet was bioequivalent to one EMTRIVA capsule (200 mg) plus one VIREAD tablet (300 mg) following single-dose administration to fasting healthy subjects (N=39).
Emtricitabine: The pharmacokinetic properties of emtricitabine are summarized in Table 4. Following oral administration of EMTRIVA, emtricitabine is rapidly absorbed with peak plasma concentrations occurring at 1–2 hours post-dose. Less than 4% of emtricitabine binds to human plasma proteins in vitro and the binding is independent of concentration over the range of 0.02–200 µg/mL. Following administration of radiolabelled emtricitabine, approximately 86% is recovered in the urine and 13% is recovered as metabolites. The metabolites of emtricitabine include 3'-sulfoxide diastereomers and their glucuronic acid conjugate. Emtricitabine is eliminated by a combination of glomerular filtration and active tubular secretion. Following a single oral dose of EMTRIVA, the plasma emtricitabine half-life is approximately 10 hours.
Tenofovir Disoproxil Fumarate: The pharmacokinetic properties of tenofovir disoproxil fumarate are summarized in Table 4. Following oral administration of VIREAD, maximum tenofovir serum concentrations are achieved in 1.0 ± 0.4 hour. Less than 0.7% of tenofovir binds to human plasma proteins in vitro and the binding is independent of concentration over the range of 0.01–25 µg/mL. Approximately 70–80% of the intravenous dose of tenofovir is recovered as unchanged drug in the urine. Tenofovir is eliminated by a combination of glomerular filtration and active tubular secretion. Following a single oral dose of VIREAD, the terminal elimination half-life of tenofovir is approximately 17 hours.
Table 4 Single Dose Pharmacokinetic Parameters for Emtricitabine and Tenofovir in Adults
|
Emtricitabine |
Tenofovir |
|---|
|
| Fasted Oral Bioavailability (%) |
92 (83.1–106.4) |
25 (NC–45.0) |
| Plasma Terminal Elimination Half-Life† (hr) |
10 (7.4–18.0) |
17 (12.0–25.7) |
| Cmax (µg/mL) |
1.8 ± 0.72 |
0.30 ± 0.09 |
| AUC‡ (µg∙hr/mL) |
10.0 ± 3.12§ |
2.29 ± 0.69 |
| CL/F‡ (mL/min) |
302 ± 94 |
1043 ± 115 |
| CLrenal‡ (mL/min) |
213 ± 89 |
243 ± 33 |
Effects of Food on Oral Absorption
Truvada may be administered with or without food. Administration of Truvada following a high fat meal (784 kcal; 49 grams of fat) or a light meal (373 kcal; 8 grams of fat) delayed the time of tenofovir Cmax by approximately 0.75 hour. The mean increases in tenofovir AUC and Cmax were approximately 35% and 15%, respectively, when administered with a high fat or light meal, compared to administration in the fasted state. In previous safety and efficacy trials, VIREAD (tenofovir) was taken under fed conditions. Emtricitabine systemic exposures (AUC and Cmax) were unaffected when Truvada was administered with either a high fat or a light meal.
Special Populations
Race
Emtricitabine: No pharmacokinetic differences due to race have been identified following the administration of EMTRIVA.
Tenofovir Disoproxil Fumarate: There were insufficient numbers from racial and ethnic groups other than Caucasian to adequately determine potential pharmacokinetic differences among these populations following the administration of VIREAD.
Gender
Emtricitabine and Tenofovir Disoproxil Fumarate: Emtricitabine and tenofovir pharmacokinetics are similar in male and female subjects.
Pediatric Patients
Truvada should not be administered to pediatric patients less than 12 years of age or weighing less than 35 kg (less than 77 lb).
Emtricitabine: The pharmacokinetics of emtricitabine at steady state were determined in 27 HIV-1-infected pediatric subjects 13 to 17 years of age receiving a daily dose of 6 mg/kg up to a maximum dose of 240 mg oral solution or a 200 mg capsule; 26 of 27 subjects in this age group received the 200 mg EMTRIVA capsule. Mean (± SD) Cmax and AUC were 2.7 ± 0.9 μg/mL and 12.6 ± 5.4 μg•hr/mL, respectively. Exposures achieved in pediatric subjects 12 to less than 18 years of age were similar to those achieved in adults receiving a once daily dose of 200 mg.
Tenofovir Disoproxil Fumarate: Steady-state pharmacokinetics of tenofovir were evaluated in 8 HIV-1 infected pediatric subjects (12 to less than 18 years). Mean (± SD) Cmax and AUCtau are 0.38 ± 0.13 μg/mL and 3.39 ± 1.22 μg•hr/mL, respectively. Tenofovir exposure achieved in these pediatric subjects receiving oral daily doses of VIREAD 300 mg was similar to exposures achieved in adults receiving once-daily doses of VIREAD 300 mg.
Geriatric Patients
Pharmacokinetics of emtricitabine and tenofovir have not been fully evaluated in the elderly (65 years of age and older).
Patients with Impaired Renal Function
The pharmacokinetics of emtricitabine and tenofovir are altered in subjects with renal impairment [See Warnings and Precautions (5.3)]. In adult subjects with creatinine clearance below 50 mL/min, Cmax, and AUC0–∞ of emtricitabine and tenofovir were increased. It is recommended that the dosing interval for Truvada be modified in patients with creatinine clearance 30–49 mL/min. Truvada should not be used in patients with creatinine clearance below 30 mL/min and in patients with end-stage renal disease requiring dialysis [See Dosage and Administration (2.2)].
Patients with Hepatic Impairment
The pharmacokinetics of tenofovir following a 300 mg dose of VIREAD have been studied in non-HIV infected subjects with moderate to severe hepatic impairment. There were no substantial alterations in tenofovir pharmacokinetics in subjects with hepatic impairment compared with unimpaired subjects. The pharmacokinetics of Truvada or emtricitabine have not been studied in subjects with hepatic impairment; however, emtricitabine is not significantly metabolized by liver enzymes, so the impact of liver impairment should be limited.
Assessment of Drug Interactions
The steady state pharmacokinetics of emtricitabine and tenofovir were unaffected when emtricitabine and tenofovir disoproxil fumarate were administered together versus each agent dosed alone.
In vitro studies and clinical pharmacokinetic drug-drug interaction trials have shown that the potential for CYP mediated interactions involving emtricitabine and tenofovir with other medicinal products is low.
No clinically significant drug interactions have been observed between emtricitabine and famciclovir, indinavir, stavudine, tenofovir disoproxil fumarate, and zidovudine (see Tables 5 and 6). Similarly, no clinically significant drug interactions have been observed between tenofovir disoproxil fumarate and abacavir, efavirenz, emtricitabine, entecavir, indinavir, lamivudine, lopinavir/ritonavir, methadone, nelfinavir, oral contraceptives, ribavirin, saquinavir/ritonavir, and tacrolimus in trials conducted in healthy volunteers (see Tables 7 and 8).
Table 5 Drug Interactions: Changes in Pharmacokinetic Parameters for Emtricitabine in the Presence of the Coadministered Drug
