The pharmacokinetics of tenofovir DF have been evaluated in healthy volunteers and HIV-1 infected individuals. Tenofovir pharmacokinetics are similar between these populations.
Absorption
Tenofovir disoproxil fumarate is a water soluble diester prodrug of the active ingredient tenofovir. The oral bioavailability of tenofovir from tenofovir disoproxil fumarate in fasted subjects is approximately 25%. Following oral administration of a single dose of tenofovir disoproxil fumarate 300 mg to HIV-1 infected subjects in the fasted state, maximum serum concentrations (Cmax) are achieved in 1.0 ± 0.4 hrs. Cmax and AUC values are 0.30 ± 0.09 mcg/mL and 2.29 ± 0.69 mcg•hr/mL, respectively.
The pharmacokinetics of tenofovir are dose proportional over a tenofovir disoproxil fumarate dose range of 75 to 600 mg and are not affected by repeated dosing.
In a single-dose bioequivalence study conducted under non-fasted conditions (dose administered with 4 oz. applesauce) in healthy adult volunteers, the mean Cmax of tenofovir was 26% lower for the oral powder relative to the tablet formulation. Mean AUC of tenofovir was similar between the oral powder and tablet formulations.
Distribution
In vitro binding of tenofovir to human plasma or serum proteins is less than 0.7 and 7.2%, respectively, over the tenofovir concentration range 0.01 to 25 mcg/mL. The volume of distribution at steady-state is 1.3 ± 0.6 L/kg and 1.2 ± 0.4 L/kg, following intravenous administration of tenofovir 1.0 mg/kg and 3.0 mg/kg.
Metabolism and Elimination
In vitro studies indicate that neither tenofovir disoproxil nor tenofovir are substrates of CYP enzymes.
Following IV administration of tenofovir, approximately 70 to 80% of the dose is recovered in the urine as unchanged tenofovir within 72 hours of dosing. Following single dose, oral administration of tenofovir disoproxil fumarate, the terminal elimination half-life of tenofovir is approximately 17 hours. After multiple oral doses of tenofovir disoproxil fumarate 300 mg once daily (under fed conditions), 32 ± 10% of the administered dose is recovered in urine over 24 hours.
Tenofovir is eliminated by a combination of glomerular filtration and active tubular secretion. There may be competition for elimination with other compounds that are also renally eliminated.
Effects of Food on Oral Absorption
Administration of tenofovir disoproxil fumarate 300 mg tablets following a high-fat meal (~700 to 1000 kcal containing 40 to 50% fat) increases the oral bioavailability, with an increase in tenofovir AUC0–∞ of approximately 40% and an increase in Cmax of approximately 14%. However, administration of tenofovir disoproxil fumarate with a light meal did not have a significant effect on the pharmacokinetics of tenofovir when compared to fasted administration of the drug. Food delays the time to tenofovir Cmax by approximately 1 hour. Cmax and AUC of tenofovir are 0.33 ± 0.12 mcg/mL and 3.32 ± 1.37 mcg•hr/mL following multiple doses of tenofovir disoproxil fumarate 300 mg once daily in the fed state, when meal content was not controlled.
Special Populations
Race: There were insufficient numbers from racial and ethnic groups other than Caucasian to adequately determine potential pharmacokinetic differences among these populations.
Gender: Tenofovir pharmacokinetics are similar in male and female subjects.
Pediatric Patients 2 Years of Age and Older: Steady-state pharmacokinetics of tenofovir were evaluated in 31 HIV-1 infected pediatric subjects 2 to less than 18 years (Table 11). Tenofovir exposure achieved in these pediatric subjects receiving oral once daily doses of tenofovir disoproxil fumarate 300 mg (tablet) or 8 mg/kg of body weight (powder) up to a maximum dose of 300 mg was similar to exposures achieved in adults receiving once-daily doses of tenofovir disoproxil fumarate 300 mg.
Table 11 Mean (± SD) Tenofovir Pharmacokinetic Parameters by Age Groups for HIV-1-infected Pediatric Patients
Dose and Formulation
| 300 mg Tablet
| 8 mg/kg Oral Powder
|
| 12 to <18 Years (N=8)
| 2 to <12 Years (N=23)
|
Cmax (mcg/mL)
| 0.38 ± 0.13
| 0.24 ± 0.13
|
AUCtau (mcg•hr/mL)
| 3.39 ± 1.22
| 2.59 ± 1.06
|
Tenofovir exposures in 52 HBV-infected pediatric subjects (12 to less than 18 years of age) receiving oral once-daily doses of tenofovir disoproxil fumarate 300 mg tablet were comparable to exposures achieved in HIV-1 infected adults and adolescents receiving once-daily doses of 300 mg.
Geriatric Patients: Pharmacokinetic trials have not been performed in the elderly (65 years and older).
Patients with Impaired Renal Function: The pharmacokinetics of tenofovir are altered in subjects with renal impairment [see Warnings and Precautions (5.2)]. In subjects with creatinine clearance below 50 mL/min or with end-stage renal disease (ESRD) requiring dialysis, Cmax, and AUC0–∞ of tenofovir were increased (Table 12). It is recommended that the dosing interval for tenofovir disoproxil fumarate be modified in patients with estimated creatinine clearance below 50 mL/min or in patients with ESRD who require dialysis [see Dosage and Administration (2.3)].
Table 12 Pharmacokinetic Parameters (Mean ± SD) of Tenofovira in Subjects with Varying Degrees of Renal Function
Baseline Creatinine Clearance (mL/min)
| >80 (N=3)
| 50 to 80 (N=10)
| 30 to 49 (N=8)
| 12 to 29 (N=11)
|
Cmax (mcg/mL)
| 0.34 ± 0.03
| 0.33 ± 0.06
| 0.37 ± 0.16
| 0.60 ± 0.19
|
AUC0-∞ (mcg•hr/mL)
| 2.18 ± 0.26
| 3.06 ± 0.93
| 6.01 ± 2.50
| 15.98 ± 7.22
|
CL/F (mL/min)
| 1043.7 ± 115.4
| 807.7 ± 279.2
| 444.4 ± 209.8
| 177.0 ± 97.1
|
CLrenal (mL/min)
| 243.5 ± 33.3
| 168.6 ± 27.5
| 100.6 ± 27.5
| 43.0 ± 31.2
|
a. 300 mg, single dose of tenofovir disoproxil fumarate
Tenofovir is efficiently removed by hemodialysis with an extraction coefficient of approximately 54%. Following a single 300 mg dose of tenofovir disoproxil fumarate, a four-hour hemodialysis session removed approximately 10% of the administered tenofovir dose.
Patients with Hepatic Impairment: The pharmacokinetics of tenofovir following a 300 mg single dose of tenofovir disoproxil fumarate 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. No change in tenofovir disoproxil fumarate dosing is required in patients with hepatic impairment.
Assessment of Drug Interactions
At concentrations substantially higher (~300-fold) than those observed in vivo, tenofovir did not inhibit in vitro drug metabolism mediated by any of the following human CYP isoforms: CYP3A4, CYP2D6, CYP2C9, or CYP2E1. However, a small (6%) but statistically significant reduction in metabolism of CYP1A substrate was observed. Based on the results of in vitro experiments and the known elimination pathway of tenofovir, the potential for CYP-mediated interactions involving tenofovir with other medicinal products is low.
Tenofovir disoproxil fumarate has been evaluated in healthy volunteers in combination with other antiretroviral and potential concomitant drugs. Tables 13 and 14 summarize pharmacokinetic effects of coadministered drug on tenofovir pharmacokinetics and effects of tenofovir disoproxil fumarate on the pharmacokinetics of coadministered drug. Coadministration of tenofovir disoproxil fumarate with didanosine results in changes in the pharmacokinetics of didanosine that may be of clinical significance. Concomitant dosing of tenofovir disoproxil fumarate with didanosine significantly increases the Cmax and AUC of didanosine. When didanosine 250 mg enteric-coated capsules were administered with tenofovir disoproxil fumarate, systemic exposures of didanosine were similar to those seen with the 400 mg enteric-coated capsules alone under fasted conditions (Table 14). The mechanism of this interaction is unknown.
No clinically significant drug interactions have been observed between tenofovir disoproxil fumarate and efavirenz, methadone, nelfinavir, oral contraceptives, ribavirin, or sofosbuvir.
Table 13 Drug Interactions: Changes in Pharmacokinetic Parameters for Tenofovira in the Presence of the Coadministered Drug
Coadministered Drug
| Dose of Coadministered Drug (mg)
| N
| % Change of Tenofovir Pharmacokinetic Parametersb (90% CI)
|
|---|
Cmax
| AUC
| Cmin
|
|---|
Atazanavirc
| 400 once daily × 14 days
| 33
| ↑ 14 (↑ 8 to ↑ 20)
| ↑ 24 (↑ 21 to ↑ 28)
| ↑ 22 (↑ 15 to ↑ 30)
|
Atazanavir/ Ritonavirc
| 300/100 once daily
| 12
| ↑ 34 (↑ 20 to ↑ 51)
| ↑ 37 (↑ 30 to ↑ 45)
| ↑ 29 (↑ 21 to ↑ 36)
|
Darunavir/ Ritonavird
| 300/100 twice daily
| 12
| ↑ 24 (↑ 8 to ↑ 42)
| ↑ 22 (↑ 10 to ↑ 35)
| ↑ 37 (↑19 to ↑ 57)
|
Indinavir
| 800 three times daily × 7 days
| 13
| ↑ 14 (↓ 3 to ↑ 33)
| ⇔
| ⇔
|
Ledipasvir/ Sofosbuvire,f
| 90/400 once daily x 10 days
| 24
| ↑ 47 (↑ 37 to ↑ 58)
| ↑ 35 (↑ 29 to ↑ 42 )
| ↑ 47 (↑ 38 to ↑ 57)
|
Ledipasvir/ Sofosbuvire,g
| 23
| ↑ 64 (↑ 54 to ↑ 74)
| ↑ 50 (↑ 42 to ↑ 59)
| ↑ 59 (↑ 49 to ↑ 70)
|
Ledipasvir/ Sofosbuvirh
| 90/400 once daily x 14 days
| 15
| ↑ 79 (↑ 56 to ↑ 104)
| ↑ 98 (↑ 77 to ↑ 123)
| ↑ 163 (↑ 132 to ↑ 197)
|
Ledipasvir/ Sofosbuviri
| 90/400 once daily x 10 days
| 14
| ↑ 32 (↑ 25 to ↑ 39)
| ↑ 40 (↑ 31 to ↑ 50)
| ↑ 91 (↑ 74 to ↑ 110)
|
Ledipasvir/ Sofosbuvirj
| 90/400 once daily x 10 days
| 29
| ↑ 61 (↑ 51 to ↑ 72)
| ↑ 65 (↑ 59 to ↑ 71)
| ↑ 115 (↑ 105 to ↑ 126)
|
Lopinavir/ Ritonavir
| 400/100 twice daily × 14 days
| 24
| ⇔
| ↑ 32 (↑ 25 to ↑ 38)
| ↑ 51 (↑ 37 to ↑ 66)
|
Saquinavir/ Ritonavir
| 1000/100 twice daily × 14 days
| 35
| ⇔
| ⇔
| ↑ 23 (↑ 16 to ↑ 30)
|
Sofosbuvirk
| 400 single dose
| 16
| ↑ 25 (↑ 8 to ↑ 45)
| ⇔
| ⇔
|
Sofosbuvir/ Velpatasvirl
| 400/100 once daily
| 24
| ↑ 55 (↑ 43 to ↑ 68)
| ↑ 30 (↑ 24 to ↑ 36)
| ↑ 39 (↑ 31 to ↑ 48)
|
Sofosbuvir/ Velpatasvirm
| 400/100 once daily
| 29
| ↑ 55 (↑ 45 to ↑ 66)
| ↑ 39 (↑ 33 to ↑ 44)
| ↑ 52 (↑ 45 to ↑ 59)
|
Sofosbuvir/ Velpatasvirn
| 400/100 once daily
| 15
| ↑ 77 (↑ 53 to ↑ 104)
| ↑ 81 (↑ 68 to ↑ 94)
| ↑ 121 (↑ 100 to ↑ 143)
|
Sofosbuvir/ Velpatasviro
| 400/100 once daily
| 24
| ↑ 36 (↑ 25 to ↑ 47)
| ↑ 35 (↑ 29 to ↑ 42)
| ↑ 45 (↑ 39 to ↑ 51)
|
Sofosbuvir/ Velpatasvirp
| 400/100 once daily
| 24
| ↑ 44 (↑ 33 to ↑ 55)
| ↑ 40 (↑ 34 to ↑ 46)
| ↑ 84 (↑ 76 to ↑ 92)
|
Sofosbuvir/ Velpatasvirq
| 400/100 once daily
| 30
| ↑ 46 (↑ 39 to ↑ 54)
| ↑ 40 (↑ 34 to ↑ 45)
| ↑ 70 (↑ 61 to ↑ 79)
|
Tacrolimus
| 0.05 mg/kg twice daily x 7 days
| 21
| ↑ 13 (↑ 1 to ↑ 27)
| ⇔
| ⇔
|
Tipranavir/ Ritonavirr
| 500/100 twice daily
| 22
| ↓ 23 (↓ 32 to ↓ 13)
| ↓ 2 (↓ 9 to ↑ 5)
| ↑ 7 (↓ 2 to ↑ 17)
|
750/200 twice daily (23 doses)
| 20
| ↓ 38 (↓ 46 to ↓ 29)
| ↑ 2 (↓ 6 to ↑ 10)
| ↑ 14 (↑ 1 to ↑ 27)
|
a. Subjects received tenofovir disoproxil fumarate 300 mg once daily.
b. Increase = ↑; Decrease = ↓; No Effect = ⇔
c. Reyataz Prescribing Information.
d. Prezista Prescribing Information.
e. Data generated from simultaneous dosing with HARVONI (ledipasvir/sofosbuvir). Staggered administration (12 hours apart) provide similar results.
f. Comparison based on exposures when administered as atazanavir/ritonavir + emtricitabine/tenofovir DF.
g. Comparison based on exposures when administered as darunavir/ritonavir + emtricitabine/tenofovir DF.
h. Study conducted with ATRIPLA (efavirenz/emtricitabine/tenofovir DF) coadministered with HARVONI.
i. Study conducted with COMPLERA (emtricitabine/rilpivirine/tenofovir DF) coadministered with HARVONI.
j. Study conducted with TRUVADA (emtricitabine/tenofovir DF) + dolutegravir coadministered with HARVONI.
k. Study conducted with ATRIPLA coadministered with SOVALDI® (sofosbuvir).
l. Comparison based on exposures when administered as atazanavir/ritonavir + emtricitabine/tenofovir DF.
m. Comparison based on exposures when administered as darunavir/ritonavir + emtricitabine/tenofovir DF.
n. Study conducted with ATRIPLA coadministered with EPCLUSA (sofosbuvir/velpatasvir).
o. Study conducted with STRIBILD (elvitegravir/cobicistat/emtricitabine/tenofovir DF) coadministered with EPCLUSA.
p. Study conducted with COMPLERA coadministered with EPCLUSA.
q. Administered as raltegravir + emtricitabine/tenofovir DF.
r. Aptivus Prescribing Information.
No effect on the pharmacokinetic parameters of the following coadministered drugs was observed with tenofovir disoproxil fumarate: abacavir, didanosine (buffered tablets), emtricitabine, entecavir, and lamivudine.
Table 14 Drug Interactions: Changes in Pharmacokinetic Parameters for Coadministered Drug in the Presence of Tenofovir Disoproxil Fumarate
Coadministered Drug
| Dose of Coadministered Drug (mg)
| N
| % Change of Coadministered Drug Pharmacokinetic Parametersa (90% CI)
|
|---|
Cmax
| AUC
| Cmin
|
|---|
Abacavir
| 300 once
| 8
| ↑ 12 (↓ 1 to ↑ 26)
| ⇔
| NA
|
Atazanavirb
| 400 once daily × 14 days
| 34
| ↓ 21 (↓ 27 to ↓ 14)
| ↓ 25 (↓ 30 to ↓ 19)
| ↓ 40 (↓ 48 to ↓ 32)
|
Atazanavirb
| Atazanavir/Ritonavir 300/100 once daily × 42 days
| 10
| ↓ 28 (↓ 50 to ↑ 5)
| ↓ 25c (↓ 42 to ↓ 3)
| ↓ 23c (↓ 46 to ↑ 10)
|
Darunavird
| Darunavir/Ritonavir 300/100 once daily
| 12
| ↑ 16 (↓ 6 to ↑ 42)
| ↑ 21 (↓ 5 to ↑ 54)
| ↑ 24 (↓ 10 to ↑ 69)
|
Didanosinee
| 250 once, simultaneously with tenofovir disoproxil fumarate and a light mealf
| 33
| ↓ 20g (↓ 32 to ↓7)
| ⇔g
| NA
|
Emtricitabine
| 200 once daily × 7 days
| 17
| ⇔
| ⇔
| ↑ 20 (↑ 12 to ↑ 29)
|
Entecavir
| 1 mg once daily x 10 days
| 28
| ⇔
| ↑ 13 (↑ 11 to ↑ 15)
| ⇔
|
Indinavir
| 800 three times daily × 7 days
| 12
| ↓ 11 (↓ 30 to ↑ 12)
| ⇔
| ⇔
|
Lamivudine
| 150 twice daily × 7 days
| 15
| ↓ 24 (↓ 34 to ↓ 12)
| ⇔
| ⇔
|
Lopinavir Ritonavir
| Lopinavir/Ritonavir 400/100 twice daily × 14 days
| 24
| ⇔ ⇔
| ⇔ ⇔
| ⇔ ⇔
|
Saquinavir Ritonavir
| Saquinavir/Ritonavir 1000/100 twice daily × 14 days
| 32
| ↑ 22 (↑ 6 to ↑ 41) ⇔
| ↑ 29h (↑ 12 to ↑ 48) ⇔
| ↑ 47h (↑ 23 to ↑ 76) ↑ 23 (↑ 3 to ↑ 46)
|
Tacrolimus
| 0.05 mg/kg twice daily x 7 days
| 21
| ⇔
| ⇔
| ⇔
|
Tipranaviri
| Tipranavir/Ritonavir 500/100 twice daily
| 22
| ↓ 17 (↓ 26 to ↓ 6)
| ↓ 18 (↓ 25 to ↓ 9)
| ↓ 21 (↓ 30 to ↓ 10)
|
Tipranavir/Ritonavir 750/200 twice daily (23 doses)
| 20
| ↓ 11 (↓ 16 to ↓ 4)
| ↓ 9 (↓ 15 to ↓ 3)
| ↓ 12 (↓ 22 to 0)
|
a. Increase = ↑; Decrease = ↓; No Effect = ⇔; NA = Not Applicable
b. Reyataz Prescribing Information.
c. In HIV-infected subjects, addition of tenofovir DF to atazanavir 300 mg plus ritonavir 100 mg, resulted in AUC and Cmin values of atazanavir that were 2.3- and 4-fold higher than the respective values observed for atazanavir 400 mg when given alone.
d. Prezista Prescribing Information.
e. Videx EC Prescribing Information. Subjects received didanosine enteric-coated capsules.
f. 373 kcal, 8.2 g fat
g. Compared with didanosine (enteric-coated) 400 mg administered alone under fasting conditions.
h. Increases in AUC and Cmin are not expected to be clinically relevant; hence no dose adjustments are required when tenofovir DF and ritonavir-boosted saquinavir are coadministered.
i. Aptivus Prescribing Information.