VIREAD
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VIREAD (VIREAD).
Tenofovir disoproxil fumarate is a nucleotide analog reverse transcriptase inhibitor (NtRTI) that undergoes intracellular phosphorylation to tenofovir diphosphate, which incorporates into viral DNA and terminates chain elongation.
| Metabolism | Tenofovir disoproxil is rapidly hydrolyzed to tenofovir; tenofovir is minimally metabolized by CYP450 enzymes. Approximately 70-80% is excreted unchanged in urine via combination of glomerular filtration and active tubular secretion. |
| Excretion | Renal: 70-80% unchanged via glomerular filtration and tubular secretion; fecal: <1% |
| Half-life | Terminal half-life: 17 hours (intracellular active metabolite tenofovir diphosphate: 60-100 hours); supports once-daily dosing |
| Protein binding | <7.2% bound to plasma proteins (negligible binding) |
| Volume of Distribution | 1.2 L/kg (independent of body weight); indicates distribution into total body water |
| Bioavailability | Oral: 25% (fasting); increased with high-fat meal (around 40%) |
| Onset of Action | Oral: Not applicable for acute effect; antiviral effect begins within days, maximal HIV RNA suppression by 4-6 weeks |
| Duration of Action | 24 hours after single dose; requires daily dosing due to intracellular half-life; duration of suppression correlates with intracellular tenofovir diphosphate |
| Action Class | Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) |
| Brand Substitutes | Tavin Tablet, Tenvir Tablet, Tenarica Tablet, Ricovir 300mg Tablet, Synflovir Tablet |
300 mg orally once daily with food.
| Dosage form | POWDER |
| Renal impairment | Creatinine clearance (CrCl) ≥50 mL/min: 300 mg every 24 hours. CrCl 30–49 mL/min: 300 mg every 48 hours. CrCl 10–29 mL/min: 300 mg every 72–96 hours. Hemodialysis: 300 mg every 7 days (after dialysis). |
| Liver impairment | No dose adjustment required for mild to severe hepatic impairment (Child-Pugh A, B, or C). |
| Pediatric use | For patients 2 to <12 years (≥10 kg): 8 mg/kg (maximum 300 mg) orally once daily. For patients ≥12 years (≥35 kg): 300 mg orally once daily. |
| Geriatric use | Select dose based on renal function; monitor renal function regularly due to age-related decline in CrCl. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VIREAD (VIREAD).
| Breastfeeding | Tenofovir is excreted into human breast milk at low concentrations (M/P ratio approximately 0.12). Studies in HIV-positive women show infant serum levels below the limit of quantification. The American Academy of Pediatrics considers tenofovir compatible with breastfeeding. However, in HIV-infected women, breastfeeding is not recommended to prevent vertical transmission. |
| Teratogenic Risk | Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data; however, a large prospective cohort study (Antiretroviral Pregnancy Registry) shows no increased risk of major birth defects. First trimester exposure: not associated with increased malformations. Second/third trimester: no fetal risks identified. Monitor for mitochondrial toxicity in neonates. |
■ FDA Black Box Warning
Lactic acidosis/severe hepatomegaly with steatosis; post-treatment exacerbation of hepatitis B.
| Serious Effects |
Hypersensitivity to tenofovir or any component of the formulation; concomitant use with other tenofovir-containing products (e.g., adefovir, other tenofovir formulations).
| Precautions | New onset or worsening renal impairment (monitor creatinine clearance and urine glucose/protein); Fanconi syndrome; risk of nephrotoxicity with concurrent or recent use of nephrotoxic agents; decreased bone mineral density; immune reconstitution syndrome; redistribution/accumulation of body fat; hepatic decompensation in patients with cirrhosis and hepatitis B. |
Loading safety data…
| Fetal Monitoring | Monitor renal function (serum creatinine, urine protein) and bone density in pregnant women receiving tenofovir. Check liver function tests if concurrent hepatotoxicity risk. Fetal monitoring includes standard prenatal ultrasound for growth and anatomy. In neonates, monitor for bone mineral density if prolonged in utero exposure. |
| Fertility Effects | Animal studies: no effect on fertility. Human data: limited. Tenofovir does not impair spermatogenesis in men or ovulation in women. No evidence of reduced fertility in women on antiretroviral therapy. Clinically, no significant impact on male or female reproductive function. |