WARNING

Tenofovir disoproxil fumarate (TDF) and Tenofovir alafenamide (TAF) are antiviral medications commonly used in the treatment of HIV and chronic hepatitis B. While both drugs are generally considered safe and effective, they do carry certain risks.

• Kidney Toxicity: Both TDF and TAF can cause kidney toxicity, particularly in individuals with pre-existing kidney conditions or those taking other medications that may affect kidney function. Routine monitoring of kidney function is typically recommended for individuals taking these medications.
• Bone Density Loss: TDF has been associated with decreased bone mineral density and an increased risk of fractures, particularly in long-term users. TAF has been developed to mitigate this risk, as it is associated with less bone density loss compared to TDF.
• Lactic Acidosis: In rare cases, both TDF and TAF can lead to a buildup of lactic acid in the blood, a condition known as lactic acidosis. This condition can be life-threatening and requires immediate medical attention.
• Hepatic Toxicity: Some individuals may experience liver toxicity while taking TDF or TAF. This is more common in individuals with underlying liver disease or those taking other medications that can affect liver function.
• Drug Interactions: TDF and TAF can interact with other medications, potentially leading to adverse effects or reduced efficacy of one or more of the drugs involved. It’s important for healthcare providers to carefully consider potential drug interactions when prescribing these medications.
• Immune Reconstitution Inflammatory Syndrome (IRIS): In individuals with HIV, starting antiretroviral therapy (ART) such as TDF or TAF can sometimes trigger an inflammatory response known as immune reconstitution inflammatory syndrome (IRIS). This can result in worsening symptoms or the development of new symptoms related to underlying infections or conditions.
• Resistance: As with any antiviral medication, there is a risk of developing drug-resistant strains of HIV or hepatitis B with prolonged use of TDF or TAF. This underscores the importance of adherence to prescribed regimens and regular monitoring of viral load.

Overall, while TDF and TAF are valuable components of HIV and hepatitis B treatment regimens, it’s essential for healthcare providers and patients to be aware of the potential risks associated with these medications and to monitor for any signs of adverse effects closely.

Why is this medication prescribed?

Tenofovir disoproxil fumarate (TDF) and Tenofovir alafenamide (TAF) are both prescribed for the treatment of human immunodeficiency virus (HIV) infection and chronic hepatitis B virus (HBV) infection. They belong to a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs), which work by interfering with the replication of the virus, thereby reducing its ability to spread and damage the immune system.

TDF and TAF are often used as part of combination therapy regimens for HIV and HBV. They are typically prescribed alongside other antiretroviral medications to form a highly active antiretroviral therapy (HAART) regimen for HIV or as part of a regimen for HBV.

How should this medicine be used?

The specific regimen and dosing of TDF or TAF will depend on factors such as the individual’s viral load, co-existing medical conditions, other medications they may be taking, and any history of drug resistance. Treatment decisions should be made by a healthcare provider experienced in managing HIV or HBV infection.

As for how TDF and TAF are used:

• Dosage: The recommended dosage of TDF or TAF can vary depending on whether it is being used for HIV or HBV treatment, the individual’s renal function, and other factors. Typically, these medications are taken once daily.
• Administration: TDF and TAF are usually available in tablet form, which is taken orally with or without food. It’s essential to follow the instructions provided by the healthcare provider or on the medication label carefully.
• Adherence: It’s crucial for individuals prescribed TDF or TAF to take the medication exactly as directed by their healthcare provider. Skipping doses or not taking the medication consistently can lead to treatment failure and the development of drug resistance.
• Monitoring: Regular monitoring of viral load, kidney function, and other relevant laboratory parameters is essential for individuals taking TDF or TAF. This helps healthcare providers assess the effectiveness of treatment, detect any adverse effects, and make necessary adjustments to the treatment regimen.

Overall, TDF and TAF are important components of HIV and HBV treatment regimens, but their effectiveness depends on appropriate use and adherence to prescribed dosing schedules. Patients should work closely with their healthcare providers to ensure safe and effective management of their condition.

Other uses for this medicine

Some potential off-label uses and areas of ongoing research may include:

• Pre-exposure prophylaxis (PrEP) for HIV: TDF, and to a lesser extent TAF, have been used as part of PrEP regimens to prevent HIV infection in individuals at high risk of acquiring the virus. PrEP involves taking antiretroviral medications regularly to reduce the risk of HIV transmission.
• Treatment of HIV or HBV in special populations: TDF and TAF may be used off-label or in clinical trials to treat HIV or HBV infection in specific populations, such as pregnant individuals, children, or individuals with coinfections such as HIV/HBV or HIV/hepatitis C virus (HCV).
• Investigational uses in other viral infections: There is ongoing research into the potential use of TDF and TAF in the treatment of other viral infections, such as herpes simplex virus (HSV), cytomegalovirus (CMV), or emerging viruses like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), although their efficacy in these contexts is not yet established.

What special precautions should I follow?

Regarding special precautions for TDF and TAF, individuals taking these medications should follow these guidelines:

• Adherence to dosing schedule: Take TDF or TAF exactly as prescribed by your healthcare provider. Skipping doses or altering the dosing schedule can affect treatment effectiveness and increase the risk of developing drug resistance.
• Kidney function monitoring: Regular monitoring of kidney function is essential while taking TDF or TAF. Your healthcare provider will likely perform blood tests to assess kidney function before starting treatment and periodically during treatment.
• Bone density monitoring: Especially for individuals taking TDF, monitoring of bone mineral density may be recommended, as TDF has been associated with bone density loss and an increased risk of fractures. TAF is associated with less bone density loss compared to TDF.
• Avoiding alcohol and certain medications: Alcohol consumption and certain medications, particularly those that can affect kidney function or interact with TDF or TAF, should be avoided or used with caution. Your healthcare provider can provide guidance on potential interactions.
• Reporting adverse effects: If you experience any unusual or severe side effects while taking TDF or TAF, such as signs of kidney toxicity, liver toxicity, or lactic acidosis, contact your healthcare provider immediately.

By following these precautions and working closely with your healthcare provider, you can safely and effectively manage your treatment with TDF or TAF.

What special dietary instructions should I follow?

There are no specific dietary instructions associated with taking TDF or TAF. However, maintaining a healthy, balanced diet can support overall health and well-being, which is important for individuals living with HIV or chronic hepatitis B. It’s recommended to follow a diet rich in fruits, vegetables, lean proteins, whole grains, and healthy fats.

What should I do if I forget a dose?

If you forget to take a dose of TDF or TAF, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you have any concerns or questions about missed doses, consult your healthcare provider for guidance. Consistency in taking your medication as prescribed is important for maintaining viral suppression and preventing the development of drug resistance.

What side effects can this medication cause?

Tenofovir disoproxil fumarate (TDF) and Tenofovir alafenamide (TAF) are generally well-tolerated medications, but like all medications, they can cause side effects in some individuals. Common side effects associated with TDF and TAF may include:

• Nausea: Some individuals may experience mild to moderate nausea, which usually resolves over time or with adjustments to the dosing schedule.
• Diarrhea: Diarrhea is a common side effect of TDF and TAF, especially when treatment is first initiated. This side effect typically improves with continued use.
• Headache: Headaches are reported by some individuals taking TDF or TAF. These headaches are usually mild and transient.
• Fatigue: Feeling tired or fatigued is a common side effect that may occur with TDF or TAF.
• Dizziness: Some individuals may experience dizziness or lightheadedness while taking TDF or TAF.
• Renal (Kidney) Toxicity: Both TDF and TAF can cause kidney toxicity in some individuals, particularly those with pre-existing kidney conditions. Symptoms of kidney toxicity may include changes in urination frequency, color, or volume, swelling in the legs or ankles, and fatigue.
• Bone Density Loss: TDF has been associated with decreased bone mineral density and an increased risk of fractures, particularly in long-term users. TAF has been developed to mitigate this risk, as it is associated with less bone density loss compared to TDF.
• Liver Toxicity: In some cases, TDF and TAF may cause liver toxicity, especially in individuals with underlying liver disease or those taking other medications that can affect liver function.
• Lactic Acidosis: Although rare, TDF and TAF can lead to a buildup of lactic acid in the blood, a condition known as lactic acidosis. Symptoms of lactic acidosis include weakness, fatigue, abdominal pain, difficulty breathing, and muscle pain or cramping.

It’s important to note that not everyone will experience these side effects, and some individuals may experience side effects not listed here. If you experience any concerning or persistent side effects while taking TDF or TAF, it’s essential to inform your healthcare provider. They can evaluate your symptoms and make any necessary adjustments to your treatment regimen.

What should I know about storage and disposal of this medication?

Storage and disposal of TDF or TAF:

Storage:

• Room Temperature: Store TDF or TAF at room temperature, away from excess heat and moisture. Avoid storing them in the bathroom or near the kitchen sink.
• Keep Container Closed: Keep the medication in its original container with the lid tightly closed to protect it from light and moisture.
• Keep Out of Reach of Children: Store TDF or TAF in a location that is out of reach of children and pets to prevent accidental ingestion.
• Do Not Share: Do not share TDF or TAF with others, even if they have similar symptoms or conditions. These medications are prescribed specifically for individual use.
• Follow Specific Instructions: Follow any specific storage instructions provided by your healthcare provider or pharmacist.

Disposal:

• Unused Medications: Dispose of any unused or expired TDF or TAF properly. Do not keep medications that are no longer needed.
• Take-Back Programs: Check with your local pharmacy or healthcare facility to see if they have a medication take-back program or other disposal options.
• Drug Disposal Guidelines: If no take-back program is available, follow the FDA guidelines for safe drug disposal. These typically involve mixing the medication with an undesirable substance (such as coffee grounds or kitty litter) in a sealed container and then disposing of it in the household trash.

In case of emergency/overdose

• Seek Medical Attention: In case of an overdose or emergency, such as accidentally taking too much TDF or TAF, seek immediate medical attention or contact a poison control center.
• Symptom Management: If someone has overdosed and is experiencing symptoms such as severe nausea, vomiting, dizziness, or difficulty breathing, call emergency services right away.

What other information should I know?

• Follow-up: Attend all follow-up appointments with your healthcare provider as scheduled to monitor your response to treatment and assess for any potential side effects or complications.
• Avoid Alcohol and Drug Interactions: Avoid consuming excessive alcohol or taking other medications without consulting your healthcare provider, as they may interact with TDF or TAF.
• Inform Healthcare Providers: Inform all healthcare providers involved in your care that you are taking TDF or TAF, including dentists and specialists, as this medication may interact with other treatments.
• Pregnancy and Breastfeeding: Inform your healthcare provider if you are pregnant, planning to become pregnant, or breastfeeding, as the safety of TDF or TAF during pregnancy and breastfeeding is not fully established.
• Adherence: Take TDF or TAF exactly as prescribed by your healthcare provider to maintain optimal treatment outcomes and prevent the development of drug resistance.

By following these guidelines for storage, disposal, and handling of TDF or TAF, as well as knowing what to do in case of an emergency or overdose, you can safely and effectively manage your medication regimen.