Tenofovir Disoproxil Fumarate (TDF) is an orally administered prodrug of tenofovir. Tenofovir is similar to Adefovir, which is used for the treatment of HIV and chronic hepatitis B virus infections.
Tenofovir is a part drug class known as nucleoside reverse transcriptase inhibitors (NRTIs). This drug is also a virus reverse transcriptase inhibitor (RTI) for hepatitis B. A group of medications that work in a similar manner is known as the class of drugs. These drugs are used for the treatment of similar conditions.
Tenofovir works similarly for HIV infection and chronic hepatitis B virus infections. This drug blocks the reverse transcriptase effectiveness. Transcriptase is an enzyme that each virus requires to make a copy of itself. Reverse transcriptase blockage can aid in the reduction of virus content in the blood. This drug can also improve CD4 cell count which are white blood cells that fight infection.
The minor side effects of this Tenofovir include depression, back pain, diarrhea, headache, trouble sleeping, and rash. While the major side effect of this class drug is muscle pain, trouble breathing, feeling of coldness in legs, fever, fatigue, abdominal pain, dark urine, puffiness and decrease bone mineral density. The minor side effects go away in few days, while the major complication has to be reported to the doctor.
Tenofovir oral tablet can lead to severe consequences if it interacts with other medications, vitamins, or herbs that the patients are taking. The substance which interacts affects the functioning of this drug.
To avoid interactions, the patient should inform of all their other drug intake to the doctor. Before getting Tenofovir prescribed the doctor should know about all herbs, vitamins, or medications intake.
Aminoglycoside group antibiotics like gentamicin and amikacin should be avoided with Tenofovir. Diclofenac, ibuprofen, and ketoprofen which are Nonsteroidal anti-inflammatory drugs should also not be taken with Tenofovir. This should be done to avoid the risk of kidney damage. Hepatitis B, hepatitis C, and anti-viral drugs should also not be taken with Tenofovir.
The dosage of Tenofovir generally depends upon age, the severity of the condition, and other medical condition of the patient. For adults, who weigh a minimum of 35 kg should be given 300mg tablet daily. While for children, the dosage depends upon their weight.
As per the U.S. Food and Drug Administration’s Adverse Event Reporting System (FAERS), a total of 11,381 adverse event reports for Truvada has been reported from 2005 to September 30, 2019. Amongst these, 8,982 were serious which includes 718 deaths.
FAERS collects voluntarily data that are reported from manufacturers, patients, doctors, and others to get the side-effect idea about the drug in real-world practice. Unfortunately, the FDA cannot verify the actual cause of the problem for this drug.
Truvada comes with a black box warning for acute exacerbation of hepatitis B post-treatment. Patients who do not continue with Truvada or other drugs which contain tenofovir disoproxil fumarate might include severe flare-ups of HBV symptoms. This might require hepatitis therapy to be restarted. The black box warning also mentions the drug usage information for PrEP in patients who are HIV-negative.
The most common side effects of this class of drugs are temporary which last not more than a month. The long-term side effects of Truvada are major which can cause kidney and liver problems along with bone degradation.
Patients who have been affected by serious side effects can file lawsuits against Gilead Sciences, Inc. The court documents state that the drugmaker was unsuccessful to warn the public of these risks.
Still, hundreds of Truvada lawsuits are pending against Gilead in state and federal court in California, as per Tenofovir Disoproxil Fumarate makers quarterly report ending June 30, 2019. The company also has to face a class action in the state.
The majority of cases are up in California, while there are plenty more in other states including Delaware and Louisiana.
Gilead stated that it intends to defend itself against lawsuits by leaving no stone unturned. The TDF makers have expressed concern that a defeat against the plaintiff could mean losses for the company.
It is believed that cases are without merit, and Gilead cannot predict the ultimate outcome. If plaintiffs successfully prove their claims, the TDF makers will have to pay out significant monetary damages. Gilead read out these things in their 2018 annual report.
Gilead makes a huge amount of money from Truvada and other HIV products. These drugs contribute to 67 percent of the company’s revenue. The company earned $14.6 B from HIV drugs in 2018 which is $1.6B profit more than what was earned in 2017.
Gilead Sciences Inc. originally developed it under the brand name Viread, tenofovir disoproxil fumarate, or TDF. Gilead sells five different TDF brand name drugs in the United States, and the drug also comes in generic form.
The U.S. FDA on October 26, 2001, approved Tenofovir disoproxil for the treatment of HIV, and on August 11, 2008, for the treatment of chronic hepatitis B.
Gilead Sciences, Inc.'s Truvada for the treatment of HIV-1 infection in adults was approved by the FDA on August 2, 2004.
The FDA approved Truvada for reducing the risk of sexually-acquired HIV infection in adults on July 16th, 2012.
The FDA expands approval for reducing the risk of HIV infection in adolescents on May 15, 2018.
In 2001, the first documented instance of kidney toxicity over the usage of TDF occurred in the United States, which was the same year the drug hit the market. The instance was reported by Willem D.F. Venter and the coauthors of a 2018 study in Southern African Journal of HIV Medicine. The patient suffered acute kidney injury (AKI), Fanconi syndrome, and nephrogenic diabetes insipidus.
AIDS Health Foundation (AHF), the largest global AIDS organization, sued Gilead in 2016, following which the TDF litigation began. The company was accused of manipulating the patent system by withholding from patients a more potent, less toxic drug called TAF.
Severe side effects:
High blood lactate