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# Tab%2525252525252525252525252525252525252525252525252525252525252525252525252525252520voihep ## Overview Tenofovir disoproxil fumarate (TDF) is a nucleotide analog reverse transcriptase inhibitor (NtRTI) used in the treatment of chronic hepatitis B virus (HBV) infection and human immunodeficiency virus (HIV) infection. ## Primary Indications * Chronic Hepatitis B Virus (HBV) Infection * Treatment of HIV-1 Infection (in combination with other antiretroviral agents) ## Adult Dosing * **Chronic HBV:** 300 mg orally once daily. * **HIV-1 Infection:** 300 mg orally once daily. ## Pediatric Dosing * **Chronic HBV:** * Ages 2 to < 12 years weighing 17 kg to < 22 kg: 150 mg orally once daily. * Ages 2 to < 12 years weighing 22 kg to < 28 kg: 200 mg orally once daily. * Ages 2 to < 12 years weighing ≥ 28 kg or ages 12 to 17 years: 300 mg orally once daily. * **HIV-1 Infection:** * Ages 2 to < 12 years weighing 17 kg to < 22 kg: 150 mg orally once daily. * Ages 2 to < 12 years weighing 22 kg to < 28 kg: 200 mg orally once daily. * Ages 2 to < 12 years weighing ≥ 28 kg or ages 12 to 17 years: 300 mg orally once daily. *Note: Dosing for children younger than 2 years or with specific weight ranges may depend on local protocols and product labeling.* ## Dose Adjustments * **Renal Impairment:** Dose adjustment is required based on creatinine clearance (CrCl). Specific dosing recommendations are available from the manufacturer or clinical guidelines. ## Contraindications * Known hypersensitivity to tenofovir disoproxil fumarate or any of its components. ## Adverse Effects Common adverse effects include nausea, diarrhea, vomiting, abdominal pain, headache, and dizziness. More serious potential adverse effects include renal toxicity (e.g., Fanconi syndrome, acute kidney injury), bone mineral density loss (osteomalacia), and lactic acidosis. ## Key Drug Interactions * **Nephrotoxic Agents:** Concurrent use with other nephrotoxic drugs (e.g., aminoglycosides, NSAIDs, certain diuretics) may increase the risk of renal toxicity. * **Didanosine:** Coadministration with didanosine can increase didanosine plasma concentrations and increase the risk of pancreatitis and peripheral neuropathy. Dosage reduction of didanosine is recommended. ## Monitoring * **Renal Function:** Monitor serum creatinine and estimated glomerular filtration rate (eGFR) regularly, especially in patients with pre-existing renal impairment or those taking other nephrotoxic drugs. * **Bone Mineral Density:** Consider monitoring bone mineral density in patients at risk for bone loss. * **Liver Function Tests:** Monitor liver function tests (e.g., ALT, AST, bilirubin) in patients treated for HBV. * **HBV DNA Levels:** Monitor HBV DNA levels to assess treatment efficacy. ## Clinical Pearls * TDF should be taken with food to improve absorption. * Patients should be advised to report any new onset of bone pain, muscle weakness, or changes in urinary output. * Due to the risk of renal toxicity, careful monitoring of renal function is paramount. * Consider alternative agents like tenofovir alafenamide (TAF) in patients with renal impairment or increased risk of bone and renal toxicity. *** **Disclaimer:** This information is intended for clinical pharmacists and healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines for complete details and to verify this information before making any treatment decisions.