Taking Biktarvy With Cat's Claw And Astralagus

There are no known or published drug interactions between Biktarvy and cat's claw or astragalus.

However, based on what we know about how cat's claw and astragalus can affect certain liver metabolizing enzymes (notably CYP34A), there are some theoretical interactions to be concerned about.

As always with over the counter drugs and supplements, you should not mix them with prescription medication without talking with your doctor first.

Biktarvy is a combination of bictegravir; emtricitabine and tenofovir alafenamide and is indicated for the treatment of HIV.

Biktarvy is intended to be used as a complete drug regimen for HIV as it contains two nucleoside analog reverse transcriptase inhibitors (emtricitabine; tenofovir alafenamide) and one integrase inhibitor (bictegravir).

It is important to remember that Biktarvy contains three drugs, and we need to take them all into account when looking into potential drug interactions.

• Drugs that inhibit or induce the liver enzyme CYP3A
• Drugs that reduce kidney function
• Drugs that inhibit or induce UGT1A1
• Drugs that inhibit or induce P-glycoprotein (P-gp)

Below are excerpts from the prescribing information of BIKTARVY discussing each of the above.

"BIC [Bictegraviris, one drug contained Biktarvy] is a substrate of CYP3A and UGT1A1. A drug that is a strong inducer of CYP3A and also an inducer of UGT1A1 can substantially decrease the plasma concentrations of BIC which may lead to loss of therapeutic effect of BIKTARVY and development of resistance. The use of BIKTARVY with a drug that is a strong inhibitor of CYP3A and also an inhibitor of UGT1A1 may significantly increase the plasma concentrations of BIC."

"TAF [Tenofovir, one component of Biktarvy] is a substrate of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Co-administration of drugs that inhibit P-gp and BCRP may increase the absorption and plasma concentrations of TAF. Coadministration of drugs that induce P-gp activity are expected to decrease the absorption of TAF, resulting in decreased plasma concentration of TAF, which may lead to loss of therapeutic effect of BIKTARVY and development of resistance."

"Because FTC [emtricitabine] and tenofovir are primarily excreted by the kidneys by a combination of glomerular filtration and active tubular secretion, coadministration of BIKTARVY with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of FTC, tenofovir, and other renally eliminated drugs and this may increase the risk of adverse reactions. Some examples of drugs that are eliminated by active tubular secretion include, but are not limited to, acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs"

So, now that we know what may potentially interact with Biktarvy, let's take a look at whether cat's claw or astragalus could cause problems.

• Diverticulitis
• Viral infections (e.g. HPV)
• Ulcers
• Osteoarthritis
• Gastritis
• Chronic fatigue syndrome (CFS)
  

Cat's claw may inhibit the liver metabolizing enzyme CYP3A4, and there have been case reports of cat's claw affecting blood levels of protease inhibitors used to treat HIV that are metabolized by CYP3A4.

The prescribing information for Biktarvy specifically warns against the use of known CYP3A4 inhibitors as they could increase concentrations of the drug, potentially increasing the risk of side effects and toxicity.

There isn't much evidence regarding cat's claw's potential to inhibit CYP3A4, but preliminary studies suggest it is a possibility. Therefore, it should not be used with CYP3A4 substrates (like Biktarvy) unless you speak with your doctor first.

• Diabetic nephropathy
• Asthma
• Cirrhosis
• Immunodeficiency
• Acute infections
• Fatigue

Astragalus is considered safe to take for most adults but does potentially have some concerning drug interactions.

For one, it is not recommended to use if you are taking immunosuppressive therapy since astragalus can stimulate the immune system. Therefore, if you are taking immunosuppressant medication, theoretically, taking astragalus might decrease its effect.

Studies also suggest that astragalus can inhibit CYP3A4 (just like cat's claw).

SInce Biktarvy relies partially on CYP3A4, astragalus could decrease the metabolism of the drug, potentially increasing side effects.

Therefore, you should not use Biktarvy with astragalus without first consulting your doctor so you can be appropriately monitored.