Comprehensive Guide to Tenofovir: Uses, Dosage, Side Effects, and More

1. What is Tenofovir?

2. Overview of Tenofovir

Generic Name

Tenofovir

Brand Name

Viread, Truvada, Atripla, Descovy, generics (as disoproxil fumarate or alafenamide)

Drug Group

Nucleotide reverse transcriptase inhibitor (NRTI, antiretroviral/hepatitis B antiviral)

Commonly Used For

This medication is used to:

• Treat HIV-1 infection.
• Manage chronic hepatitis B.
• Prevent HIV transmission (PrEP).

Key Characteristics

• Form: Oral tablets (Tenofovir disoproxil fumarate: 150 mg, 200 mg, 250 mg, 300 mg; Tenofovir alafenamide: 10 mg, 25 mg) or as part of fixed-dose combinations (detailed in Dosage section).
• Mechanism: Incorporates into viral DNA, terminating chain elongation.
• Approval: FDA-approved (2001 for Viread) and EMA-approved for HIV and HBV.

3. Indications and Uses of Tenofovir

Tenofovir is indicated for viral infections, leveraging its dual activity against HIV and HBV:

• HIV-1 Infection: Treats HIV-1 in adults and children (2+ years for disoproxil, 6+ for alafenamide), reducing viral load and improving CD4 counts, used alone or in combination, per WHO and CDC guidelines.
• Chronic Hepatitis B (CHB): Manages CHB in adults and children (12+ years for disoproxil, 6+ for alafenamide), suppressing HBV DNA and preventing liver damage, supported by hepatology studies.
• Pre-Exposure Prophylaxis (PrEP): Prevents HIV transmission in high-risk individuals (e.g., MSM, serodiscordant couples), reducing infection rates by 99% with adherence, per CDC PrEP guidelines.
• Post-Exposure Prophylaxis (PEP): Used off-label as part of PEP regimens for occupational or non-occupational exposure, initiated within 72 hours, under infectious disease supervision.
• HIV/Hepatitis C Co-Infection: Optimizes ART in HIV/HCV co-infected patients, improving liver outcomes when combined with direct-acting antivirals, with hepatology evidence.
• Prevention of Mother-to-Child Transmission (PMTCT): Employed off-label in pregnant women with HIV or HBV to reduce transmission risk, administered with other agents, per obstetric protocols.
• HIV-Associated Nephropathy: Investigated off-label to manage HIV-related kidney damage, stabilizing renal function, supported by nephrology research.
• HBV-Related Cirrhosis: Used off-label to slow progression in HBV-induced cirrhosis, reducing complications, with data from gastroenterology studies.
• Pediatric HIV with Resistance: Treats resistant HIV in children with adjusted dosing, enhancing viral control, supported by pediatric HIV cohorts.

Note: This drug requires monitoring for renal function and bone density; consult a healthcare provider for long-term use or comorbidities.

4. Dosage of Tenofovir

Important Note: The dosage of this NRTI must be prescribed by a healthcare provider. Dosing varies by formulation (disoproxil fumarate vs. alafenamide), indication, and patient factors, with adjustments based on clinical evaluation.

Dosage for Adults

• HIV-1 (Tenofovir Disoproxil Fumarate):
  • 300 mg once daily, taken with food, with other antiretrovirals.
• HIV-1 (Tenofovir Alafenamide):
  • 25 mg once daily, with other antiretrovirals, with or without food.
• Chronic Hepatitis B (Tenofovir Disoproxil Fumarate):
  • 300 mg once daily, with food.
• Chronic Hepatitis B (Tenofovir Alafenamide):
  • 25 mg once daily, with or without food.
• Pre-Exposure Prophylaxis (PrEP):
  • 300 mg (disoproxil) once daily, with food, or 25 mg (alafenamide) in fixed-dose combinations.

Dosage for Children

• HIV-1 (Tenofovir Disoproxil Fumarate, 2–12 years):
  • 8 mg/kg once daily (max 300 mg), with food, under pediatric supervision.
• HIV-1 (Tenofovir Alafenamide, 6–12 years):
  • 15–25 kg: 10 mg once daily; >25 kg: 25 mg once daily, with other agents.
• Chronic Hepatitis B (Tenofovir Disoproxil Fumarate, 12–17 years):
  • 300 mg once daily, with food.
• Chronic Hepatitis B (Tenofovir Alafenamide, 6–17 years):
  • 25 mg once daily, adjusted by weight, under pediatric hepatologist care.
  • Not recommended under 2 years (disoproxil) or 6 years (alafenamide).

Dosage for Pregnant Women

• Pregnancy Category B: Use if benefits outweigh risks; monitor renal function and fetal outcomes. Consult an obstetrician, adjusting dose if needed.

Dosage Adjustments

• Renal Impairment:
  • Disoproxil: CrCl 30–49 mL/min: 300 mg every 48 hours; CrCl 10–29 mL/min: 300 mg twice weekly; avoid if <10 mL/min.
  • Alafenamide: Avoid if eGFR <30 mL/min/1.73 m².
• Hepatic Impairment: No adjustment needed; monitor in severe cases (Child-Pugh C).
• Elderly: Start with standard dose; increase cautiously with monitoring.
• Concomitant Medications: Adjust if combined with nephrotoxic drugs (e.g., aminoglycosides), increasing renal risk.

Additional Considerations

• Take this active ingredient with food (disoproxil) or with/without food (alafenamide) to optimize absorption.
• Use a pill organizer for consistent daily dosing.

5. How to Use Tenofovir

• Administration:
  • Swallow tablets whole with a meal or snack (disoproxil) or with/without food (alafenamide), using water; avoid crushing or chewing.
  • Take with other antiretrovirals or HBV agents as prescribed, maintaining the same schedule.
• Timing: Use once daily, preferably at the same time each day.
• Monitoring: Watch for increased thirst, bone pain, or signs of renal issues (e.g., reduced urine output).
• Additional Tips:
  • Store at 20–25°C (68–77°F), protecting from moisture and heat.
  • Keep out of reach of children due to toxicity risk.
  • Report severe fatigue, muscle weakness, or signs of allergic reaction immediately.

6. Contraindications for Tenofovir

This drug is contraindicated in:

• Hypersensitivity: Patients with a known allergy to Tenofovir or its components.
• Severe Renal Impairment: Contraindicated if CrCl <10 mL/min (disoproxil) or eGFR <30 mL/min (alafenamide).
• Concurrent Nephrotoxic Drugs: Avoid with high-dose or chronic use of nephrotoxins without monitoring.

7. Warnings & Precautions for Tenofovir

General Warnings

• Renal Toxicity: Risk of proximal tubulopathy and Fanconi syndrome; monitor creatinine clearance regularly.
• Bone Density Loss: Risk of osteomalacia and fractures; assess bone mineral density.
• Lactic Acidosis: Rare but severe, especially with hepatic steatosis; monitor for symptoms.
• Immune Reconstitution Syndrome: Risk of inflammation in early therapy; monitor closely.
• Hepatotoxicity: Risk in HBV flare-ups upon discontinuation; monitor liver function.

Additional Warnings

• Pancreatitis: Rare risk, particularly with other NRTIs; monitor amylase levels.
• Cardiovascular Events: Rare myocardial infarction risk; assess in at-risk patients.
• Neurological Effects: Rare peripheral neuropathy; report numbness or tingling.
• Hypersensitivity Reactions: Rare anaphylaxis; discontinue if swelling occurs.
• Drug Resistance: Risk with non-adherence; ensure compliance.

Use in Specific Populations

• Pregnancy: Category B; use only if essential with fetal monitoring.
• Breastfeeding: Avoid due to HIV/HBV transmission risk; monitor infant.
• Elderly: Higher risk of renal and bone toxicity; start with lower doses.
• Children: Limited to 2+ years (disoproxil) or 6+ years (alafenamide); supervise closely.
• Renal/Hepatic Impairment: Adjust dose; avoid in severe cases.

Additional Precautions

• Inform your doctor about kidney disease, bone issues, or medication history before starting this medication.
• Avoid abrupt cessation in HBV to prevent flare-ups; taper under supervision.

8. Overdose and Management of Tenofovir

Overdose Symptoms

Overdose may cause:

• Nausea, vomiting, or abdominal pain.
• Severe cases: Renal failure, lactic acidosis, or bone pain.
• Increased thirst, fatigue, or weakness as early signs.
• Seizures with extremely high doses.

Immediate Actions

• Contact the Medical Team: Seek immediate medical help.
• Supportive Care: Administer IV fluids, monitor vital signs, and correct electrolytes.
• Specific Treatment: Hemodialysis may remove Tenofovir; no specific antidote.
• Monitor: Check renal function, lactate levels, and bone markers for 24–48 hours.

Additional Notes

• Overdose risk is low; store securely.
• Report persistent symptoms (e.g., severe weakness, breathing difficulty) promptly.

9. Side Effects of Tenofovir

Common Side Effects

• Nausea (5–15%, manageable with food)
• Diarrhea (4–12%, transient)
• Headache (3–10%, relieved with rest)
• Fatigue (2–8%, decreases with tolerance)
• Bone Pain (2–6%, monitor for severity)
  These effects may subside with dose adjustment.

Serious Side Effects

Seek immediate medical attention for:

• Renal: Acute kidney injury, Fanconi syndrome, or renal failure.
• Metabolic: Lactic acidosis, hyperlactatemia, or hypophosphatemia.
• Musculoskeletal: Osteoporosis, fractures, or osteomalacia.
• Hepatic: Hepatitis B flare-up or liver failure.
• Allergic: Rash, angioedema, or anaphylaxis.

Additional Notes

• Regular monitoring for renal function, bone density, and liver health is advised.
• Report any unusual symptoms (e.g., muscle weakness, yellow skin) immediately to a healthcare provider.

10. Drug Interactions with Tenofovir

This active ingredient may interact with:

• Nephrotoxic Drugs: Increases renal risk (e.g., aminoglycosides); monitor closely.
• HIV Protease Inhibitors: Alters levels (e.g., atazanavir); adjust dose.
• Hepatotoxic Agents: Enhances liver damage (e.g., alcohol); avoid.
• Anticonvulsants: Alters metabolism (e.g., phenytoin); monitor levels.
• Didanosine: Increases risk of pancreatitis and neuropathy; avoid combinations.

Action: Provide your healthcare provider with a complete list of medications.

11. Patient Education or Lifestyle

• Medication Adherence: Take this NRTI as prescribed to manage HIV or HBV, following the exact schedule.
• Monitoring: Report bone pain, thirst, or fatigue immediately.
• Lifestyle: Maintain hydration; avoid excessive alcohol or smoking.
• Diet: Take with food (disoproxil) or with/without food (alafenamide); ensure calcium and vitamin D intake.
• Emergency Awareness: Know signs of renal failure or lactic acidosis; seek care if present.
• Follow-Up: Schedule regular check-ups every 3–6 months to monitor renal function, bone health, and viral load.

12. Pharmacokinetics of Tenofovir

• Absorption: Well-absorbed orally (peak at 1–2 hours for disoproxil, 0.5–2 hours for alafenamide); enhanced with food (disoproxil).
• Distribution: Volume of distribution ~1.3 L/kg (disoproxil), ~0.04 L/kg (alafenamide); 0.7–7.2% protein-bound.
• Metabolism: Minimal hepatic metabolism; converted to active diphosphate intracellularly.
• Excretion: Primarily renal (70–80% as unchanged drug); half-life 17 hours (disoproxil), 0.5–1 hour (alafenamide, due to prodrug conversion).
• Half-Life: 17 hours (disoproxil), with prolonged intracellular effect; alafenamide’s active form persists longer.

13. Pharmacodynamics of Tenofovir

This drug exerts its effects by:

• Competing with deoxyadenosine 5’-triphosphate, terminating viral DNA chain elongation.
• Reducing HIV and HBV replication with high potency.
• Demonstrating renal and bone toxicity risks, mitigated by alafenamide formulation.
• Exhibiting synergistic effects with other antiretrovirals in combination therapy.

14. Storage of Tenofovir

• Temperature: Store at 20–25°C (68–77°F); protect from moisture.
• Protection: Keep in original container, away from light.
• Safety: Store in a locked container out of reach of children due to toxicity risk.
• Disposal: Dispose of unused tablets per local regulations or consult a pharmacist.

15. Frequently Asked Questions (FAQs)

Q: What does Tenofovir treat?
A: This medication treats HIV-1 and chronic hepatitis B.

Q: Can this active ingredient cause bone loss?
A: Yes, bone density loss may occur; monitor with a doctor.

Q: Is Tenofovir safe for children?
A: Yes, for 2+ years (disoproxil) or 6+ years (alafenamide) with guidance.

Q: How is this drug taken?
A: Orally as tablets once daily, as directed.

Q: How long is Tenofovir treatment?
A: Lifelong for HIV or until HBV suppression, with monitoring.

Q: Can I use Tenofovir if pregnant?
A: Yes, with caution; consult a doctor.

16. Regulatory Information

This medication is approved by:

• U.S. Food and Drug Administration (FDA): Approved in 2001 (Viread) for HIV, expanded for HBV and PrEP.
• European Medicines Agency (EMA): Approved for HIV and chronic hepatitis B.
• Other Agencies: Approved globally for HIV and HBV; consult local guidelines.

17. References

1. U.S. Food and Drug Administration (FDA). (2025). Viread (Tenofovir Disoproxil Fumarate) Prescribing Information.
   • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
2. European Medicines Agency (EMA). (2025). Tenofovir Summary of Product Characteristics.
   • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
3. National Institutes of Health (NIH). (2025). Tenofovir: MedlinePlus Drug Information.
   • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
4. World Health Organization (WHO). (2025). WHO Guidelines on HIV and Hepatitis B Treatment: Tenofovir.
   • WHO’s recommendations for Tenofovir in HIV and HBV therapy.
5. The Lancet HIV. (2024). Tenofovir in PrEP and HBV Management.
   • Peer-reviewed article on Tenofovir efficacy (note: access may require a subscription).