How Does Tenofovir Interact with Other Substances?

Tenofovir is nearly present in all drugs that are used to combat HIV. It may also be present in several other drug combinations. Although this drug is highly effective and tolerable, what are the adverse effects that may arise? How severe is tenofovir drug-drug or drug-disease interaction? Here is an in-depth discussion for all things tenofovir interactions.

Tenofovir disoproxil has been around for many years. Its efficacy in treatment and prevention has earned a good reputation as a combination of drug treatment for various health conditions. Most of these conditions are complex and involve highly effective meds.

The negative side effects of a drug can’t be fully avoided in the pharma industry. No matter how effective a drug can be, its side effects and health warnings must be taken seriously. At HIVPrEP, we discussed how tenofovir helps treat health conditions as well as its negative effects that must be checked to assure patient safety at all treatment therapies.

🔍What Is Tenofovir Prescribed For?

Tenofovir DF (also TDF) is a highly effective medicine used as an active substance in combination with other medicines to treat various health conditions.

In most cases, this medicine is prescribed in addition to another active medicine (ingredient) as a drug for the following medical conditions:

• as an anti-HIV medication. It’s used as an antiretroviral med in addition to one or more other drugs to combat the HIV virus in the body;
• as HBV medicine. Tenofovir in combination with another drug is used to treat and reduce the amount of HBV virus in the liver cells;
• as PrEP. Tenofovir was popularized with the introduction of Truvada as the first choice of drug for preventing HIV from entering the blood cells. For high effectiveness of this med, practice safer sex and change or get rid of risky lifestyle choices to decrease the risk of a virus entering your body.

Tenofovir is also used together with other meds as PEP. Although this drug doesn’t cure the aforementioned conditions, like HIV and HBV, its mechanism of action reduces the amount of virus in the blood making the patient healthier and stronger in fighting virus-related conditions.

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🔁Drug-Disease Interactions

As the research paced ahead with a prodrug of tenofovir DF with the new version (tenofovir alafenamide) of an active substance that is more tolerable, tenofovir is known to cause adverse drug-disease interactions.

Patient health is paramount and it’s your responsibility not to take tenofovir without first consulting with a doctor. Let a medical specialist completely assess your health for any possible health condition.

It’s also your responsibility to let your medical specialist know about your past health conditions such as liver or bone problems, kidney disease, and others.

Tenofovir is known to interact with some illnesses causing adverse effects that may seriously harm your health [1].

For example:

• hepatitis B. This is a major disease interaction with tenofovir. If you have been diagnosed with HBV and suddenly stop using meds containing tenofovir, there might be a risk of HBV returning or worsening. It’s very important to stick to the prescription and let your medical specialist keep track of HBV right from beginning meds containing TDF. It also important to continue monitoring for several months after stopping the medication;
• hepatotoxicity. Any drug belonging to the NRTIs drug class including tenofovir or meds containing the composition of this drug class including abacavir is known to cause lactic acidosis. It’s very important to cautiously administer medication while paying attention to lactic acidosis;
• renal dysfunction is known to be serious with the use of TDF. Primarily, TDF is eliminated by the kidney and can cause acute renal failure and other related problems. A doctor should monitor this condition and administer the right dose adjustment while adhering to drug safety and effectiveness;
• bone toxicity. A new pro-drug of TDF – TAF – is known to be highly safe with very minimal effect to BMD;
• liver disease.

If you have any of the above health conditions, administer tenofovir tabs only under doctor’s care. In case of any adverse effects, your doctor should end the use of tenofovir medication. This is to avoid any health problems that may be restarted including drug resistance after stopping the medication.

💊Main Drug-Drug Interactions of Tenofovir

Drug-drug interaction between medicines is common. In fact, many informative websites list a total of 174 drugs that can interact with tenofovir. While you are prescribed TDF in combination with other meds, be aware of various drug interactions that might arise.

As a first step, consult with your medical specialist about the meds you are using. List all of them, even recreational drugs or herbal therapies. Some drugs can cause severe interactions that might harm your health or minor ones that can easily be managed.

A doctor can always assure you if any med you need to co-administer with tenofovir can cause any harmful reaction. Understanding drug classes that cause adverse reactions is important.

Antiretrovirals Meds

Tenofovir is an antiretroviral med belonging to the NRTIs drug class. It’s very risky and it may cause health complications if you co-administer any med that contains another antiretroviral.

Drugs that inhibit and depend on the same enzymes (or inhibitors) can cause a reduction in the metabolism of other medicines leading to increased drug levels (or high drug concentrations in the body) and potential medicine toxicity [2]. This also includes protease inhibitors.

Be aware and avoid drugs that contain antiretroviral such as darunavir, abacavir, didanosine (such as Videx EC – delayed-release capsules), zidovudine, and atazanavir, Harvoni, and others.

Pills for Hepatitis

Tenofovir is also prescribed for HBV treatment as a combination with another anti-HBV drug (mostly emtricitabine or lamivudine). TDF is a highly effective medicine that replaces earlier the use of adefovir due to its superiority [3].

Using drugs that are used to treat HBV while using tenofovir medication should be avoided. This may cause a higher concentration of TDF in the body leading to adverse side effects.

HBV is also indicated as a warning when administering TDF drug combinations. If you stop this medication suddenly, HBV may become worse or reappear. Close monitoring and dose adjustment should be made if you must use both drugs at the same time.

Tenofovir Vs Other Medications

There are several other meds that interact with TDF. Some of these interactions are major or moderate while others are minor. Minor effects can cause interactions but don’t demand medical attention.

When a patient experiences severe interactions, these meds are usually not taken with tenofovir and should be avoided at all costs, or a doctor can adjust the dosage if it’s really necessary. These meds include adefovir, intravenous pentamidine, intravenous aminoglycosides, capreomycin, foscarnet, high-dose methotrexate, amphotericin B, cisplatin, gallium nitrate, vancomycin, and non-steroidal anti-inflammatory agents.

Serious interactions may be caused by foscarnet, inotersen and orlistat, and others.

Prior to administering any medicine, confirm with a doctor if it’s safe with tenofovir. Always stick to drug prescription to reduce drug ineffectiveness and possible side effects.

🍎How Does Tenofovir Interact with Food?

Although taking tenofovir with food is indicated as minor drug interaction, there is no known effect that has been recorded. Tenofovir is well tolerated with any type of food and you don’t have to adjust your meals.

As it is commonly checked with most medications, grapefruits are frequently known to cause some drug interaction either with minor or moderate effects. Grapefruit juice can have a moderate interaction with TDF. Caution is advised when administering tenofovir as it may result in increased absorption of tenofovir. And in this case, it’s necessary to monitor associated effects or adverse reactions.

A combination of garlic (in high amounts) and antiretroviral drugs may alter the levels of NNRTIs medicines like Truvada. Garlic supplements may lower the levels of anti-HIV meds.

🍷Can Tenofovir Be Mixed with Alcohol?

Alcohol is often contraindicated when taking various medications. Drinking alcohol with tenofovir has no known drug interaction or effect. Nonetheless, alcohol is not good for your health, especially if you do consume excessively.

Alcohol contributes to various health problems. Drugs in the body may have altered or negative effects, adverse reactions, or render the drug ineffective in treating a certain health condition.

When using tenofovir, it is necessary to avoid or limit the use of alcohol for safe drug efficacy and tolerability. If you have other illnesses and use tenofovir alongside alcohol, your condition may get worse.

Your medical specialist is always your best advisor on how to safely take tenofovir to effectively treat your health condition with higher efficacy and tolerability. Your doctor is who you can openly talk to about all the meds you are using and other health issues you may be encountering.

📚References:

1. Truvada (emtricitabine / tenofovir) Disease Interactions. Drugs.com.
2. Drug Interactions with Antiretroviral Medications. John J. Faragon, PharmD, BCPS, AAHIV-P, Rebecca G. Kinney, MD. Retrieved June 12th, 2017. Hiv.uw.edu.
3. Tenofovir for the treatment of hepatitis B virus. Jenh AM, Thio CL, Pham PA. Retrieved 2009 Oct;29(10):1212-27. Ncbi.nlm.nih.gov.