VEMLIDY 25 MG (TENOFOVIR ALAFENAMIDE) – MEDICAL DESCRIPTION

Antiviral Medication | Chronic Hepatitis B Treatment

VEMLIDY 25 MG is an antiviral medication containing Tenofovir Alafenamide (TAF), a nucleotide analogue reverse transcriptase inhibitor (NtRTI). It is indicated for the treatment of chronic hepatitis B virus (HBV) infection in adults and eligible pediatric patients with compensated liver disease.

Tenofovir alafenamide works by inhibiting viral replication, helping reduce hepatitis B viral load and control ongoing viral activity. Its formulation delivers the active antiviral agent efficiently into liver cells while generally producing lower circulating tenofovir exposure than tenofovir disoproxil fumarate (TDF).

Composition and Pharmaceutical Form

Composition detail: Each tablet contains tenofovir alafenamide fumarate equivalent to 25 mg of tenofovir alafenamide. The tablet also contains inactive ingredients, including lactose monohydrate.

Indications and Uses

VEMLIDY 25 MG is indicated for:

• Chronic Hepatitis B (HBV): Treatment of chronic hepatitis B virus infection in adults and pediatric patients aged 6 years and older weighing at least 25 kg, with compensated liver disease.
• Viral Load Suppression: Helps reduce HBV DNA levels by inhibiting viral replication.
• Liver Disease Management: Helps control viral activity and reduce ongoing HBV-related liver inflammation.
• Reduction of Disease Progression Risk: Long-term viral suppression may help reduce the risk of complications associated with chronic hepatitis B, including liver fibrosis and cirrhosis.

Important: VEMLIDY controls HBV replication but does not necessarily eliminate the virus or cure chronic hepatitis B. It is not indicated as a stand-alone treatment for HIV infection.

Mechanism of Action

Tenofovir alafenamide is a prodrug that is converted intracellularly into its active metabolite, tenofovir diphosphate.

It works through the following mechanisms:

1. Cellular Activation: Enters target cells and undergoes conversion into tenofovir diphosphate.
2. Viral Enzyme Inhibition: The active metabolite inhibits HBV DNA polymerase, an enzyme essential for viral replication.
3. DNA Chain Termination: Competes with natural nucleotides and interferes with viral DNA synthesis, resulting in premature termination of the growing DNA chain.
4. Viral Replication Suppression: Reduces the ability of hepatitis B virus to multiply, helping achieve sustained viral suppression.

Pharmacological advantage: Compared with TDF, tenofovir alafenamide generally provides lower systemic tenofovir exposure while maintaining effective intracellular antiviral concentrations. This is associated with a more favorable renal and bone safety profile in clinical studies.

Dosage and Method of Administration

Recommended dosage:

• Adults: One 25 mg tablet once daily.
• Pediatric patients: One 25 mg tablet once daily in patients aged 6 years and older weighing at least 25 kg, according to the approved product information.
• Take the tablet orally with food.
• Swallow the tablet whole with water.
• Take the medication at approximately the same time every day.

Missed dose:

• If a dose is missed and less than 18 hours have passed from the usual dosing time, take it as soon as possible with food.
• If more than 18 hours have passed, skip the missed dose and take the next dose at the usual time.
• Do not take a double dose to compensate for a missed dose.

Duration of treatment:

Treatment is generally long-term. Its duration depends on the patient's HBV status, liver condition, treatment response, and physician's assessment.

Do not discontinue VEMLIDY without medical supervision. Stopping hepatitis B antiviral therapy may cause a severe acute exacerbation of hepatitis B, potentially resulting in serious liver complications.

Possible Side Effects

VEMLIDY is generally well tolerated. However, some patients may experience adverse effects.

Common or reported side effects:

• Headache.
• Abdominal pain.
• Nausea.
• Fatigue.
• Diarrhea.
• Cough.
• Back pain.

Potentially serious adverse effects:

• Renal Impairment: New or worsening kidney problems, including renal tubular abnormalities.
• Lactic Acidosis: A rare but potentially life-threatening accumulation of lactic acid in the blood.
• Severe Hepatomegaly with Steatosis: Rare enlargement of the liver associated with fatty accumulation.
• Hepatitis B Exacerbation: Severe worsening of hepatitis B following discontinuation of treatment.

Patients should seek immediate medical attention if they experience unusual muscle weakness, persistent nausea, severe abdominal discomfort, breathing difficulties, or symptoms suggesting significant liver or kidney problems.

Contraindications and Precautions

The U.S. prescribing information does not list specific formal contraindications for VEMLIDY. Nevertheless, several important precautions apply.

Special precautions:

• HIV Infection: Patients should be tested for HIV before starting treatment. VEMLIDY alone should not be used to treat HIV infection because inadequate HIV treatment may lead to antiviral resistance.
• Renal Impairment: Assess kidney function before and during treatment, including serum creatinine, estimated creatinine clearance, urine glucose, and urine protein.
• Chronic Kidney Disease: Serum phosphorus should also be monitored in patients with chronic kidney disease.
• Severe Renal Impairment: Not recommended in patients with estimated creatinine clearance below 15 mL/min who are not receiving chronic hemodialysis.
• Hepatic Impairment: Not recommended in patients with decompensated liver disease (Child-Pugh B or C).
• Treatment Discontinuation: Patients stopping therapy require close clinical and laboratory monitoring for several months because of the risk of hepatitis B flare-ups.
• Bone Health: Patients with osteoporosis or other risk factors for bone disease should discuss appropriate monitoring with their physician.

Drug Interactions

Tenofovir alafenamide is a substrate of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Medications that strongly affect these transport proteins may alter its absorption and effectiveness.

Important interactions include:

• Rifampicin: May significantly reduce tenofovir alafenamide exposure.
• Rifabutin and Rifapentine: May decrease drug concentrations and antiviral effectiveness.
• Anticonvulsants: Carbamazepine, oxcarbazepine, phenobarbital, and phenytoin may reduce drug exposure.
• St. John's Wort: May reduce tenofovir alafenamide concentrations.
• Other Antiviral Medications: Certain antiviral combinations may require additional assessment to avoid interactions or unnecessary duplication of tenofovir-containing therapy.

Patients should inform their physician or pharmacist about all prescription medications, over-the-counter products, and herbal supplements they are taking before starting treatment.

Pregnancy and Breastfeeding

• Pregnancy: Treatment decisions should be individualized by a healthcare professional after assessing potential benefits and risks.
• Breastfeeding: Women with chronic hepatitis B should consult their physician before breastfeeding while receiving treatment. Decisions should consider maternal health, infant HBV prevention, and the available safety information.

Pregnant women with hepatitis B require appropriate monitoring and medical management to reduce the risk of mother-to-child transmission.

Storage Conditions

• Store at room temperature according to the manufacturer's recommended conditions.
• Keep the tablets in their original container to protect them from moisture.
• Keep the container tightly closed.
• Protect from excessive heat and direct sunlight.
• Keep out of reach of children.
• Do not use after the expiry date.

Patient Disclaimer

This description is intended for educational and informational purposes only. It does not replace professional medical advice, diagnosis, or treatment.

VEMLIDY 25 MG is a prescription medication that should be used under the supervision of a qualified healthcare professional. Patients should follow the prescribed dosage and undergo regular medical and laboratory monitoring during treatment.

Do not stop taking VEMLIDY without consulting your physician, as discontinuation may result in a serious worsening of hepatitis B infection.

References

1. U.S. FDA – DailyMed: Official VEMLIDY prescribing information, including indications, dosage, contraindications, warnings, adverse reactions, and drug interactions. VEMLIDY – FDA/DailyMed.
2. European Medicines Agency (EMA): Official VEMLIDY product information, including composition, pharmacology, clinical indications, and administration. VEMLIDY – EMA Product Information.
3. Gilead Sciences: Official VEMLIDY prescribing information and clinical safety information. VEMLIDY – Official Prescribing Information.
4. Singapore National Drug Formulary: Registered product information and approved indications for VEMLIDY 25 mg. VEMLIDY – National Drug Formulary.
5. U.S. National Library of Medicine: Detailed drug labeling and pharmacological information. Tenofovir Alafenamide – Drug Label Information.