Tenofovir

Tenofovir

Tenofovir is a potent antiviral medication that has become a cornerstone in treating and managing HIV and chronic hepatitis B. This medicine has changed the lives of many patients, offering hope and improved health outcomes. Tenofovir tablets work by stopping the virus from multiplying, which helps control the infection and reduce its impact on the body.

Let's explore the uses of tenofovir and how it works to combat viral infections. We'll also look at the proper way to take this medication, possible side effects, and necessary precautions to remember.

What is Tenofovir?

Tenofovir medicine belongs to a class of drugs called nucleotide analogue reverse transcriptase inhibitors (NRTIs). This medication works by decreasing the amount of HBV and HIV in the blood, helping to manage these chronic conditions effectively.

There are two primary forms of tenofovir:

Tenofovir Disoproxil Fumarate (TDF): This form is used to treat HIV-1 infection in adults and children two years of age and older who weigh at least 10 kg. TDF is also effective in treating chronic hepatitis B in the same age group and weight range.

Tenofovir Alafenamide (TAF): This form treats chronic hepatitis B in adults and children 12 years and older with stable liver disease.

It's important to note that tenofovir is not a cure for either HIV or hepatitis B. Instead, it helps manage these conditions by reducing the viral load in the body.

Tenofovir Tablet Uses

• The following are some common uses of tenofovir:
• Treatment of hepatitis B virus (HBV)
• Treatment of human immunodeficiency virus (HIV)
• Reduces the risk of developing HIV complications and AIDS
• For HIV treatment, doctors prescribe tenofovir along with other antiretroviral medicines.

How to Use Tenofovir Tablet

Patients need to take tenofovir correctly to get the most benefit from this medicine. Here's a guide on how to use tenofovir tablets:

• Tablet tenofovir is often part of a combination regimen. Take all the medicines your doctor prescribed at the right time of day for better effectiveness. Do not take more or less of it or more often than prescribed.
• Tenofovir DF tablets are usually taken once daily, with or without food. On the other hand, patients should take tenofovir AF tablets once daily with food.
• Take tenofovir at the same time every day to maintain consistent drug concentrations in your body.
• Don't skip doses, as missing doses can make the virus resistant to medications, making it harder to treat.
• Continue taking tenofovir even if you feel well. Don't stop without talking to your doctor first.

Tenofovir DF is available as an oral powder for patients who can't swallow tablets. Here's how to use it:

• Use the dosing scoop provided in the package to measure the right amount of powder.
• Add the powder to 2 to 4 ounces of soft food like applesauce, baby food, or yoghurt. Mix the powder and food thoroughly with a spoon.
• Eat the mixture right away to avoid a bitter taste.
• Don't store the scoop inside the package with the powder.

Side Effects of Tenofovir Tablets

Tablet tenofovir, like many medications, can cause side effects.

Common Side Effects:

• Diarrhoea
• Headache
• Depression
• Rash or itching
• Difficulty falling asleep or staying asleep
• Nausea or vomiting
• Gas, heartburn, or indigestion
• Weight loss
• Back pain

Serious Side Effects:

• Lactic Acidosis: Symptoms include weakness, irregular or rapid heartbeat, dizziness, muscle pain, stomach pain with nausea and vomiting, trouble breathing, and feelings of coldness in the legs or arms.
• Liver Problems: Watch for signs such as dark urine, abdominal pain or discomfort, fatigue, yellowing of the skin and eyes (jaundice), and nausea.
• Kidney Issues: Symptoms may include fatigue, aching, puffiness, decreased urination and swelling of feet and ankles.
• Bone Problems: Tenofovir may cause decreased bone mineral density, leading to ongoing or worsening bone pain.
• Immune Reconstitution Syndrome: As the immune system strengthens, it may respond to previously hidden infections in the body.

Other serious side effects that warrant immediate medical attention include:

• Pain in the upper right part of the stomach
• Dizziness or lightheadedness
• Fast or irregular heartbeat
• Shortness of breath or fast breathing
• Cold or blue-coloured hands and feet
• Signs of infection (fever, chills, or sore throat)

Precautions

Taking tenofovir requires careful consideration of several important factors to ensure safe and effective treatment, including:

• Medicinal History: It's essential to inform the doctor about all ongoing medications, including prescription, nonprescription, herbal, or vitamin supplements, as tenofovir interacts with several other drugs.
• Regular Check-ups: Tenofovir may increase the risk of broken bones (fractures) and kidney problems, including kidney failure. To reduce these risks, patients should follow up with all blood tests ordered by their doctor and avoid other medications that may harm the kidneys, such as certain antiviral or NSAID pain medicines.
• Dosing Precaution: You should not change your dose or stop using this drug without talking to your doctor first.
• Avoid Alcohol: Limit or avoid alcoholic beverage consumption, as it may increase the risk of the drug's adverse effects, such as pancreatitis and liver issues.
• Prevent Transmission: It's important to note that tenofovir does not lower the risk of transmitting HIV infection, so patients should practice safe sex and avoid sharing needles to prevent transmission.

How Tenofovir Tablet Works

Tenofovir decreases the amount of HIV and HBV in the blood, making it an effective treatment for both infections.

When a patient takes tenofovir, the body absorbs and converts it to its active form. This active form, tenofovir diphosphate, acts as a chain terminator. It competes with the natural building blocks of viral DNA, specifically deoxyadenosine 5'-triphosphate. By doing so, tenofovir prevents the virus from replicating effectively.

In HIV treatment, tenofovir targets the reverse transcriptase enzyme, which is crucial for viral reproduction. It interferes with this enzyme's ability to copy the virus's genetic material, halting the spread of HIV in the body and lowering the viral load.

For hepatitis B, tenofovir works by inhibiting the HBV polymerase. This enzyme is essential for the hepatitis B virus to replicate its DNA. By blocking this process, tenofovir reduces the virus load in the liver and blood.

Tenofovir's effectiveness lies in its ability to target viral enzymes while having a low affinity for human cellular DNA polymerases. This selectivity means it can disrupt viral replication without significantly interfering with normal cellular processes, contributing to its safety profile.

Can I Take Tenofovir with Other Medicines?

Tenofovir can interact with other drugs, including:

• Antibiotics like amikacin and gentamicin
• Abacavir
• Abemaciclib
• Abrocitinib
• Adefovir
• Bupropion
• Celecoxib
• Didanosine
• Diflunisal
• Feprazone
• Indomethacin
• Itraconazole
• Mefenamic Acid
• Orlistat
• Other HIV medications, such as atazanavir
• Pain medications, such as aceclofenac and acemetacin

Dosing Information

Tenofovir is available in various forms, including tablets (150 mg, 200 mg, 250 mg, and 300 mg) and oral powder (40 mg/g). The oral powder benefits children or adults who have difficulty swallowing tablets. The tenofovir dosage depends on the patient's age, weight, and medical condition.

• For HIV Infection Treatment: 
  • For adults and children two years of age and older weighing 35 kg or more, the standard dose is 300 mg once daily. Children weighing less than 35 kg receive a weight-based dose:
    • 28 to less than 35 kg: 250 mg once daily
    • 22 to less than 28 kg: 200 mg once daily
    • 17 to less than 22 kg: 150 mg once daily
• For Chronic Hepatitis B Infection:
  • Adults and children two years and older weighing 35 kg or more take 300 mg (7.5 scoops of oral powder) once daily. The dose is adjusted based on weight for children weighing less than 35 kg.

FAQ's

1. What is tenofovir used for?

Tenofovir is a powerful antiviral medication used to treat two significant viral infections: HIV and chronic hepatitis B virus (HBV). For HIV treatment, doctors prescribe tenofovir along with other antiretroviral medicines to control the infection. Tenofovir helps to lower the amount of HIV and hepatitis B virus in the blood, allowing the immune system to function better.

2. Why is tenofovir taken at night?

Tenofovir is usually taken once daily, with or without food. However, some doctors may recommend taking it at bedtime. Taking tenofovir at bedtime may make certain side effects less bothersome, like dizziness, drowsiness, or difficulty concentrating.

3. Is tenofovir safe for the liver?

Tenofovir is generally considered safe for the liver. It's used to treat chronic hepatitis B infection, which affects the liver. However, in rare cases, tenofovir may cause liver problems. Patients should know the signs of liver injury, such as dark urine, abdominal pain or discomfort, yellowish discolouration of the eyes and skin, fatigue, and nausea. If these symptoms occur, it's crucial to seek medical attention immediately.

4. Is tenofovir bad for the kidneys?

Tenofovir can have an impact on kidney function in some patients. It may increase the risk of kidney problems, including kidney failure. It's essential to follow up with all blood tests ordered by your doctor and avoid other medications that may harm the kidneys, such as certain antiviral or NSAID pain medicines.

5. What to avoid when taking tenofovir?

When taking tenofovir, patients should avoid:

• Skipping doses or stopping the medicine without consulting their doctor.
• Taking other medications without discussing them with their doctor.
• Consuming alcohol excessively.
• Sharing needles or engaging in unprotected sex.

6. What is the age limit for tenofovir?

Tenofovir has been approved for use in children aged two years and older who weigh at least 10 kg. Adults have no upper age limit, but dosage adjustments may be necessary for older patients, especially those with reduced kidney function. Tenofovir is not approved for use in infants under two years of age.

7. What is the best time to take tenofovir?

Tenofovir is typically taken once daily. The best time to take it is at the same time each day to maintain consistent levels of the drug in your body. Some patients find it helpful to take tenofovir with food to reduce stomach upset. However, individuals can take it with or without food.

8. Does tenofovir result in hair loss?

Hair loss is not a commonly reported adverse effect of tenofovir. However, a recent case series has reported alopecia (hair loss) associated with tenofovir alafenamide (TAF), a newer form of tenofovir, in African American females. This appears to be a rare occurrence, and more research is needed to understand the relationship between tenofovir and hair loss.

9. Does tenofovir cause weight gain?

The relationship between tenofovir and weight changes is complex. Some studies suggest that tenofovir disoproxil fumarate (TDF) may be linked with weight loss or weight suppression. In contrast, switching from TDF to tenofovir alafenamide (TAF) has been related to weight gain in some patients, particularly when combined with other antiretroviral medications.