What Is Tenofovir Alafenamide?

Tenofovir Alafenamide (TAF), sold under the brand name Vemlidy, is an antiviral medication used to treat chronic hepatitis B virus (HBV) infection in adults and pediatric patients 6 years of age and older weighing at least 25 kg with compensated liver disease. It is manufactured by Gilead Sciences.

TAF is a newer, improved prodrug of tenofovir that delivers the active drug more efficiently to target cells, allowing a lower dose with fewer kidney and bone side effects compared to the older formulation, Tenofovir Disoproxil Fumarate (TDF/Viread). TAF is also a key component in several combination HIV treatment and prevention medications.

How does Tenofovir Alafenamide work?

Tenofovir Alafenamide belongs to a class of drugs called nucleotide reverse transcriptase inhibitors (NtRTIs). After you take the tablet, TAF is absorbed and converted inside your cells into its active form, tenofovir diphosphate. This active metabolite works by blocking an enzyme called reverse transcriptase that the hepatitis B virus needs to copy its genetic material. By incorporating itself into the viral DNA chain and causing premature termination, TAF stops the virus from replicating.

Compared to the older prodrug TDF, TAF reaches higher concentrations in liver cells and lymphoid tissue while maintaining lower levels in the blood, which is why it causes fewer kidney and bone-related side effects.

What doses are available for Tenofovir Alafenamide?

• 25 mg oral tablet (Vemlidy) — the only standalone TAF formulation available. Taken once daily with food.

Tenofovir Alafenamide is also available as a component in several combination HIV medications, including Biktarvy, Descovy, Genvoya, Odefsey, and Symtuza, but these are separate products with different indications.

How hard is it to find Tenofovir Alafenamide in stock?

Tenofovir Alafenamide (brand name Vemlidy) scores a 55 out of 100 on our findability scale, meaning it can be moderately difficult to locate. While there is no active FDA shortage for the standalone product, Vemlidy is a specialty medication that is not stocked at every pharmacy. Some pharmacies may need to special-order it, and TAF-containing combination products have experienced intermittent supply disruptions. If your local pharmacy doesn't have it, Medfinder can help you locate a pharmacy with Vemlidy in stock near you.

Who Can Prescribe Tenofovir Alafenamide?

Tenofovir Alafenamide is typically prescribed by:

• Hepatologists — liver specialists who manage chronic hepatitis B
• Gastroenterologists — specialists in digestive system conditions including liver disease
• Infectious Disease specialists — doctors who treat viral infections including HBV and HIV
• Internal Medicine physicians and Primary Care providers — may initiate or continue therapy, especially in areas with limited specialist access

Telehealth appointments are available for ongoing management and prescription refills in many cases.

Is Tenofovir Alafenamide a controlled substance?

No, Tenofovir Alafenamide is not a controlled substance. It has no abuse potential and is not scheduled by the DEA. It can be prescribed with standard prescriptions and refills without the restrictions that apply to controlled medications.

Common Side Effects of Tenofovir Alafenamide

Most side effects of Tenofovir Alafenamide are mild. The most commonly reported include:

• Headache (12%)
• Abdominal pain (9%)
• Cough (8%)
• Back pain (6%)
• Fatigue (6%)
• Nausea (6%)
• Joint pain (5%)
• Diarrhea (5%)
• Indigestion (5%)

⚠️ Boxed Warning: Discontinuation of Tenofovir Alafenamide may result in severe acute exacerbations of hepatitis B. Do not stop taking this medication without your doctor's guidance. Your liver function must be closely monitored for at least several months after discontinuation.

Alternative Medications to Tenofovir Alafenamide

If Tenofovir Alafenamide is unavailable or not suitable for you, your doctor may consider these alternatives for chronic hepatitis B treatment:

• Tenofovir Disoproxil Fumarate (TDF/Viread) — the older prodrug of tenofovir; effective but associated with more kidney and bone side effects
• Entecavir (Baraclude) — a nucleoside analog with high potency and a high barrier to resistance; a common first-line alternative
• Lamivudine (Epivir-HBV) — an older, inexpensive option but with higher rates of drug resistance over time
• Adefovir Dipivoxil (Hepsera) — an older nucleotide analog; less commonly used today due to resistance and toxicity concerns

Always consult your healthcare provider before switching medications.

Drug Interactions with Tenofovir Alafenamide

Tenofovir Alafenamide can interact with several medications. Key interactions include:

• P-glycoprotein inducers (Rifampin, Rifabutin, Carbamazepine, Phenobarbital, Phenytoin) — can significantly decrease TAF blood levels and reduce effectiveness
• St. John's Wort — may substantially reduce TAF levels; avoid concurrent use
• Aminoglycosides — increased risk of kidney damage when used together
• High-dose or multiple NSAIDs — increased risk of renal impairment
• Other nephrotoxic agents — may worsen kidney side effects

Always inform your doctor and pharmacist about all medications, supplements, and herbal products you take.

Final Thoughts on Tenofovir Alafenamide

Tenofovir Alafenamide (Vemlidy) is a well-tolerated, effective treatment for chronic hepatitis B that offers significant safety advantages over its predecessor TDF. While the brand-name price is high at $1,500–$1,800 per month, Gilead's co-pay assistance and patient access programs can bring the cost down to $0 for many eligible patients.

As a specialty medication, Vemlidy may not be stocked at every pharmacy. If you're having trouble finding it, Medfinder can help you locate a pharmacy with Tenofovir Alafenamide in stock near you. Never stop taking this medication without medical supervision due to the risk of hepatitis B flare-ups.