Introduction
Taf 25 is used in the treatment of HIV infection and chronic hepatitis B virus (HBV) infection. It prevents the multiplication of virus in human cells. This stops the virus from producing new viruses and clears up your infection.
Taf 25 should be used in the dose and duration as advised by your doctor. Do not skip any doses and finish the full course of treatment even if you feel better. Take it with food, as this increases the absorption of the medicine into the body. It is important to keep taking them until your doctor tells you it is safe to stop.
Some people may experience headache as a side effect of this medicine . Please consult your doctor if it persists for a longer duration. These are usually not serious but tell your doctor if they bother you or do not go away. Rarely, some people may experience a skin reaction or liver damage. Your doctor will closely monitor you for these in the initial period of treatment.
Before taking it, tell your doctor if you have any skin problems or liver or kidney disease. While using it, you may need regular blood tests to check your blood counts and liver function. Avoid drinking alcohol as it may increase your risk of liver damage. Pregnant or breastfeeding mothers should consult their doctor before using this medicine. Do not have unprotected sex or share personal items like razors or toothbrushes, if you are HIV positive. Talk to your doctor about safe ways like condoms to prevent HIV transmission during sex.
Uses of Taf 25
- HIV infection
- Chronic hepatitis B virus (HBV) infection
How to use Taf 25
Take this medicine in the dose and duration as advised by your doctor. Swallow it as a whole. Do not chew, crush or break it. Taf 25 is to be taken empty stomach.
How Taf 25 works
Taf 25 is an antiviral medication. It prevents the multiplication of virus in human cells. This stops the virus from producing new viruses and clears up your infection.
What if you forget to take Taf 25?
If you miss a dose of Taf 25, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.
Indication
Chronic Hepatitis B Infection
Administration
Take with food
Adult Dose
Chronic Hepatitis B Infection
Indicated for treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease
25 mg PO qDay with food
Hepatic impairment
Mild (Child-Pugh A): No dosage adjustment required
Decompensated (Child-Pugh B or C) hepatic impairment: Use not recommended
Renal Dose
Renal impairment
Mild, moderate, or severe: No dosage adjustment required
ESRD (CrCl <15 mL/min): Use not recommended
Contraindication
Hypersensitivity
Mode of Action
Tenofovir alafenamide (AF) is a nucleotide reverse transcriptase inhibitor (NRTI) and a phosphonamidate prodrug of tenofovir
Compared with tenofovir disoproxil fumarate (tenofovir DF, Viread), tenofovir AF is a more targeted form of tenofovir that has demonstrated high antiviral efficacy at a dose that is 10 times lower than tenofovir DF, as well as an improved renal and bone safety profile
Tenofovir AF as a lipophilic cell-permeant compound enters primary hepatocytes by passive diffusion and by the hepatic uptake transporters OATP1B1 and OATP1B3 and is converted to tenofovir diphosphate
Tenofovir diphosphate inhibits HBV replication through incorporation into viral DNA by the HBV reverse transcriptase, which results in DNA chain-termination
Precaution
Lactic acidosis and severe hepatomegaly with steatosis, including fatalities, reported with nucleoside analogs, including tenofovir disoproxil fumarate in combination with other antiretrovirals; most were reported in women; obesity and prolonged nucleoside exposure may be risks factors
Discontinuation of antihepatitis B drugs may result in severe acute exacerbations of hepatitis B
Owing to the risk of development of HIV-1 resistance, tenofovir AF alone is not recommended for the treatment of HIV-1 infection; test for HIV-1 before initiating treatment
Lactation
Unknown if distributed in human breast milk
Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition
Side Effect
1-10%
Headache (9%)
ALT >5 x ULN (8%)
Abdominal pain (7%)
Fatigue (6%)
Cough (6%)
Glycosuria >3+ (5%)
Nausea (5%)
Back pain (5%)
Pregnancy Category Note
There are no human data on use in pregnant women to inform a drug-associated risks of adverse fetal developmental outcome
In animal studies, no adverse developmental effects were observed when tenofovir alafenamide was administered during the period of organogenesis at exposure equal to or 51 times (rats and rabbits, respectively) the tenofovir alafenamide exposure at the recommended daily dose
Interaction
Drugs that induce P-gp result in decreased tenofovir AF absorption and plasma concentrations, which may lead to loss of therapeutic effect (eg, carbamazepine, oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentine, St John’s wort)
Drugs that inhibit P-gp and BCRP may increase tenofovir AF absorption and plasma concentration.
Coadministration of tenofovir AF with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of tenofovir and other renally eliminated drugs, and this may increase the risk of adverse reactions
Some examples include acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides, high-dose or long-term NSAD use