Tenofovir Alafenamide: What Should You Know About It?

Having been approved, TDF was a breakthrough in preventing and treating HIV as a combination drug. Although it has a high positive profile, adverse effects are something that worries medical specialists. Tenofovir alafenamide (TAF) is a new prodrug of TDF that’s not inferior to TDF and is much less likely to affect renal and BMD. It’s the drug that’s best for HIV treatment.

TAF is a drug from Gilead Sciences. There are several reasons to compare the two active ingredients of the drugs based on their tolerability and adverse effects. TAF got FDA approval as a treatment drug for chronic hepatitis B (HBV) as a stand-alone med under the brand name Vemlidy (approved Nov 10, 2016, and its patent is expected to expire in 2022).

TAF was also approved as a combination treatment with other drugs to combat the HIV virus. These include the following: (1) Descovy – TAF+emtricitabine (FTC), (2) Biktarvy – TAF+FTC+bictegravir, (3) Genvoya – elvitegravir+cobicistat + FTC + TAF, (4) Odefsey – emtricitabine+rilpivirine, and (5) Symtuza – darunavir+cobicistat+FTC+ TAF. At HIVPrEP, we will explore the benefits of TAF over TDF as a treatment for HBV as well as HIV medication.

💡Tenofovir Alafenamide Uses

TAF is the first choice drug to treat chronic HBV infection. It has a high efficacy and is a tolerable drug that works by stopping or decreasing the growth or replication of the virus. If left untreated, a infection can lead to serious liver damage (commonly known as cirrhosis) and liver cancer.

Tenofovir alafenamide has another important use. As a prodrug of tenofovir, it’s one of its kind that acts as a drug combination in treating the HIV infection. This drug has a greater advantage compared to TDF which presents itself with many safety concerns, especially renal problems and BMD reduction.

TAF has a one-tenth dose of TDF resulting in a 90% decrease of circulating TDF plasma (particularly Genvoya). The effect of this formulation is fewer renal problems and BMD.

TAF – under brand name Genvoya is in research base for HIV prevention (or PrEP). The outcome is yet to be confirmed.

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🔬Mechanism of Action

As a prodrug of tenofovir, TAF is an NRTI that’s designed to inhibit the virus in the blood cells and limit its ability to use the cell DNA to replicate (viral DNA).

Once HIV enters the body, it uses the CD4 cells to make more copies of the virus. The more it replicates, the more it weakens immune function resulting in the intrusion of other opportunistic infections taking their advantage and causing other illnesses.

TAF blocks the HIV enzyme – reverse transcriptase, thus prohibiting the target virus from multiplying. The outcome is to reduce the amount of HIV in the body and give the body immune system the strength it needs to fully fight any opportunistic infection that may enter the body.

Unlike TDF, tenofovir alafenamide is more effective in delivering tenofovir to target cells (T-cells) resulting in lower plasma and kidney exposures [1].

👨‍⚕️Correct Dose and Administration

When used as an HBV treatment, it’s important to test for the HIV-1 infection. This is because TAF should not be used alone if you test positive for both HBV and HIV. Another HIV drug should be combined with it to treat HIV infection.

As directed by your medical specialist, take TAF (Vemlidy 25 mg) tablets by mouth with a meal, usually 1 tab a day – every day at the same time to ensure the levels of the drug concentration in the body remain stable.

To ensure you safely use this medicine without any unwelcome effects, it’s necessary to consult with a doctor about your health and the drugs you are using. The dosage can be adjusted based on your medical condition as well as other meds you may be taking.

List all the drugs or products you use including prescription meds, OTC drugs, recreational drugs, and herbal products.

For a safe and effective treatment with either HBV or HIV, do not take more or less of TAF than what is recommended or prescribed by a medical specialist. Never stop taking this medication unless directed to do so by your doctor. Abruptly stopping the medication may make the infection worse or harder to treat (it can lead to drug resistance), or worsen adverse reactions or side effects.

As an HIV treatment, there are drugs that are formulated together with TAF. These drugs are single-tablet regimen – available as an FDC or as a stand-alone drug. Examples include Genvoya, Descovy, Biktarvy, Odefsey, and Symtuza.

🤕What Are the Side Effects of TAF?

As it’s a new drug for HIV treatment, the side effects have not been fully documented (or not complete). The good news is that this drug was designed to limit adverse reactions that are normally present in TDF medication.

Side effects of this drug are those that can be portrayed by using one of these meds: Symtuza, Odefsey, Descovy, Genvoya, Biktarvy, Symtuza, and Vemlidy.

Staying safe from side effects involves visiting a doctor before drug administration and consistently using the medicine as prescribed by a medical specialist.

Notable effects:

• headache;
• tiredness;
• cough.

Depending on your health, many people taking this TAF do not experience serious side effects.

Nonetheless, serious effects may include:

• depression;
• anxiety;
• signs of kidney problems;
• unusual thirst;
• signs of liver problems including nausea, lack of appetite, stomach pain, etc.;
• lactic acidosis such as rapid deep breathing, unusual weakness drowsiness, vomiting, etc.;
• allergic reactions.

Adverse effects can be managed if you consult with a doctor to assess your health condition. In the case that you experience any of the above signs, talk to your doctor without delay.

🔁Main Drug Interactions

Drug interaction is something common in the pharmacy realms. Although TAF was designed to limit adverse reactions, drug interaction may still be something to consider. It’s always necessary to talk to your doctor about all the drugs you are using. Let know of your previous or current illnesses, as well.

Allergy to TAF may exist in some patients due to TAF’s inactive ingredients. TAF may worsen your condition or lead to adverse effects if you have a kidney condition, HIV infection, hepatotoxicity, liver conditions (including hep C, and cirrhosis), renal dysfunction, bone problems, or pancreatitis.

Can You Take This Drug with 🍔Food and 🥃Alcohol?

TAF has no interaction with food or alcohol. Although it can’t be ruled out completely, there might be some foods that cause minor interactions with TAF as a drug combination with other HIV medicines or as a stand-alone prodrug to treat HBV.

As with alcohol, there is no known interaction with TAF. But it’s necessary to limit the use of alcohol. Alcohol is known to contribute to drug side effects and make the drug ineffective in its main function. If you can’t avoid its consumption, drink less so as for the drug to give high efficacy and tolerability with fewer side effects.

💊Drug-Drug Interactions

Drug-drug interactions can possibly occur if you use it in a combination. You should not take this drug without a recommendation from a doctor. In total there are about 157 major and 82 drug interactions [2].

If you know you take any medicine for the following conditions, let your doctor know prior to taking TAF:

• Prograf (tacrolimus) med;
• rifampicin (such as rifadin, rimactane, rifadin IV);
• other tenofovir drugs (or NRTIs meds);
• hepatotoxicity drugs;
• other drugs for HBV;
• nephrotoxic drugs;
• meds to treat asthma, chronic bronchitis, emphysema.

There are several medicines that we didn’t list (but you should know). Your doctor can help you with the right dose prescription to keep your health safe.

⚖Tenofovir Alafenamide Versus Tenofovir Disoproxil Fumarate

The mechanism of action of tenofovir disoproxil fumarate is associated with high plasma tenofovir concentrations which are thought to be the cause of serious renal and bone toxic effects especially in Truvada and other drugs with TDF combinations.

TAF is a novel tenofovir prodrug with a 90% reduction level in plasma tenofovir concentrations. These levels can mean improved renal and bone safety [3].

Tenofovir alafenamide containing regimens is non-inferior compared to tenofovir disoproxil fumarate-containing regimens.

In terms of drug safety, while being effective and tolerable, TAF is being tested and it already has noted benefits on safety; it is going to be the best replacement for TDF.

There are many research programs comparing TDF vs TAF. One study shows that TAF has no serious kidney-related effects. In contrast, TDF is very much associated with adverse effects of kidney-related problems, including 4 deaths. In the same study, BMD is far less and safe with TAF. TAF –based regimen gives a low percentage of only 1% of the assessed population compared to TDF-based regimen which resulted with 3% bone loss. Statistically, these results are significantly important [4].

Overall, TAF proves to be more tolerable when it comes to drug adverse effects as discussed above. This is the goal of any drug – to have a drug that’s well-tolerated and highly effective. As research continues and TAF continues to gain significant improvements over tenofovir, it will eventually be the new drug to replace TDF. TDF is extremely effective but concerns come when looking at the drug’s side effects and precautions.

📜Conclusion

Both drugs have somehow the same effectiveness, but tenofovir is known to be related to some major health conditions. It’s not that TAF doesn’t have the same effect, but rather its effects are much more tolerable and safe for patients with severe health conditions.

As a drug that treats both HBV and HIV infection, you can get this medicine from healthcare, clinics/pharmacies, or via mail order online. Brand medications are extremely expensive but there is a cost-effective approach to get the same drug formulation at a substantially lower cost. This is by using generics from other manufacturers such as Mylan. Generics are approved and have the same effectiveness and quality as their original counterparts.

People can buy original drugs such as Vemlidy for HBV or branded versions for HIV. If you are concerned about affordability, we recommend you try generics OTC. You save hundreds of dollars when you buy over-the-counter. It’s also convenient and you can plan how you want your drugs delivered to you.

Choose the best high-rated and trustworthy drugstore that fulfills all your needs. Take care to avoid fake medicines or losing your money. Don’t just order from an unknown source. Do the research and get the best supplier. Some suppliers add discounts, offers, or free drug samples. If you need to test their drugs’ effectiveness, you can order free samples before making bulk orders.

📚References:

1. Tenofovir alafenamide: A novel prodrug of tenofovir for the treatment of Human Immunodeficiency Virus. Adrian S. Ray, Marshall W. Fordyce, Michael J.M.Hitchcock. Volume 125, January 2016, Pages 63-70. Retrieved 27 Nov. 2015. Sciencedirect.com.
2. Tenofovir alafenamide Drug Interactions. Drugs.com.
3. Tenofovir alafenamide versus tenofovir disoproxil fumarate, coformulated with elvitegravir, cobicistat, and emtricitabine, for initial treatment of HIV-1 infection: two randomised, double-blind, phase 3, non-inferiority trials. Dr Prof Paul E Sax, MD, David Wohl, MD, Prof Michael T Yin, MD, Frank Post, MD, Edwin DeJesus, MD, and others. Volume 385, ISSUE 9987, P2606-2615, June 27, 2015.
4. TAF vs. TDF (original tenofovir)—improvements in safety. Retrieved November 2015. Catie.ca.