Emtricitabine and Tenofovir - Uses, Warnings, Side Effects, Dosage, and More

What Is the Emtricitabine and Tenofovir Combination?

The Emtricitabine and Tenofovir combination is a type of antiviral medicine used to treat HIV/AIDS and to reduce the risk of getting HIV in people who are at high risk. This medicine belongs to a group called nucleoside reverse transcriptase inhibitors (NRTIs).

Both Emtricitabine and Tenofovir work by blocking the virus from multiplying in the body. For people living with HIV, this combination is always taken along with other HIV medicines and should never be used alone.

Even when taken correctly with other antiviral drugs, this combination does not cure HIV/AIDS, but it helps slow the progression of the disease, protects the immune system, and reduces complications.

When used for prevention, this medicine can lower the chance of getting HIV, especially when combined with safe practices such as condom use and regular medical follow-ups.

How Does the Emtricitabine and Tenofovir Combination Work?

Emtricitabine and Tenofovir help control the harmful effects of the human immunodeficiency virus (HIV) in people who are already HIV-positive. They also help reduce the risk of HIV infection in people who are not infected but are at high risk.

This combination works by blocking an enzyme called reverse transcriptase, which HIV needs to make copies of itself inside the body. By stopping this process, the medicines slow down the multiplication of the virus and help protect the immune system.

Uses of Emtricitabine and Tenofovir Combination:

• To treat patients affected by HIV. It is always used in combination with any other antiviral drugs.

• It is also used as pre-exposure prophylaxis (PrEP) against HIV in patients who do not have HIV to prevent HIV infection.

Dosage of Emtricitabine and Tenofovir Combination:

Emtricitabine and Tenofovir combination should be taken per the physician's advice and should never be taken without getting a prescription.

This tablet is available in four different dosages.

• 100 mg of Emtricitabine and 150 mg of Tenofovir.

• 133 mg of Emtricitabine and 200 mg of Tenofovir.

• 167 mg of Emtricitabine and 250 mg of Tenofovir.

• Emtricitabine 200 mg and Tenofovir 300 mg is the widely used combination.

Warning

Infections:

Emtricitabine and Tenofovir might show certain symptoms and signs of infections, such as fever, shivering, cough, sore throat, pain while passing urine, etc. In such cases, the symptoms should be brought to the doctor's notice.

Hypersensitivity Reactions:

Allergy or hypersensitivity reactions have been reported in some cases for this drug combination. Symptoms like swollen face, lips, or tongue, along with itching, have been reported. In such cases, medical help should be sought.

Kidney Problems:

If symptoms such as pain or difficulty while urinating, changes in the color or amount of urine might indicate a reaction associated with the kidney, in such cases, medical intervention is required.

Liver Problems:

Symptoms associated with the stools and urine, such as dark-colored urine, light-colored stools, pain in the upper belly, yellowish discoloration of the skin and nails, etc., might indicate a liver abnormality due to this combination, which needs medical attention as well. Hepatomegaly (liver enlargement) has also been reported in some cases.

Medications:

When taking this combination of drugs, make sure that any other medication containing these drugs (Emtricitabine, Tenofovir, Lamivudine) is not taken, as there will be drug overdose or interactions and side effects.

Lactic Acidosis:

This combination has a side effect of building up lactic acid in the blood, called lactic acidosis, which might present as breathing difficulty, weakness, feeling dizzy, muscle pain, stomach pain, etc.

Hepatitis B:

This drug should not be stopped abruptly without a doctor's advice in patients who have had hepatitis B infection previously, as it can trigger hepatitis B to become active and worsen over time. Thus, it should be kept in check constantly through tests.

HIV Status:

If used as a PrEP drug, make sure to confirm that the patient is HIV negative before prescribing and starting the medication, as it can make the patient resistant to the drug in case the patient is positive.

Bone Density:

A decrease in bone mineral density has been noted in a few patients after taking this combination of drugs as a treatment or as prophylaxis.

For Patients

When and Why to Take Emtricitabine and Tenofovir Combination?

This combination is taken strictly after getting prescribed by a physician and undergoing an HIV test. Making sure if the person is positive or negative for HIV comes a long way in deciding the usage of this drug either as a prophylaxis or treatment.

This drug combination is used in treating patients affected by HIV in combination with any other antiviral drugs. It is also used as pre-exposure prophylaxis (PrEP) against HIV in patients who are HIV negative yet want to prevent themselves from contracting HIV infection.

How Effective Is Emtricitabine and Tenofovir Combination Against AIDS?

These drugs block the pathways of entry for the virus into the immune system of the body. When this combination is taken on an everyday basis, it is noticed that these drugs can effectively stop the virus from making its entry into the system (in HIV-negative individuals) and slow down the spread into the body (in HIV-positive individuals).

According to the U.S Centers for Disease Control and Prevention, these drugs minimize the risk of getting HIV by 99 % when combined with safe sexual practices by using contraceptives such as condoms. As far as the treatment with this combination, these drugs, when used with other retroviral drugs, can effectively slow down the disease's progression, but cannot cure the disease as a whole.

This drug combination decreases the levels of HIV in the blood and increases the level of CD4 T, which makes the immune system strong and helps prevent opportunistic infections.

Things to Inform Your Doctor Before They Prescribe You Emtricitabine and Tenofovir Combination:

Inform your doctor about the following:

• Prior history of allergy or hypersensitivity reactions.

• Inform about the pregnancy status (planning pregnancy or breastfeeding). These drugs were noticed to be extracted in breast milk.

• If taking any medication, as this drug has interactions with certain drugs, do not forget to mention even if a vitamin or a herbal supplement is taken. Also, mention if you are taking any other medications containing one of these drugs (that is, Emtricitabine or Tenofovir).

• If you have taken any medications for AIDS previously, and if that medication worked.

• Habits such as alcohol and drugs, if any.

• History of medical conditions like renal problems, liver disorders, bone-related disorders, or any other medical conditions.

• Previous history of any infections like Hepatitis B.

How to Take Emtricitabine and Tenofovir Combination?

A prescription is a must before taking this drug combination. If prescribed, ask your doctor how to take the drug and what all should be considered before taking it.

• It should be taken as prescribed, nothing more or less.

• When taken as a treatment for HIV, the antiviral drugs prescribed with this combination of drugs should be taken as well.

• When taken as a precautionary drug, it should always be combined with contraceptive precautions such as the use of condoms during sexual intercourse.

• This combination is available in tablet form and should be taken orally once a day, every day at the same time.

• This combination can be taken before or after food with water.

• Always stock up on the drug. Do not skip a dose of Emtricitabine and Tenofovir combination even for a single day, as stopping the drug only for a short term can make the disease progress rapidly.

• Do not stop the drug abruptly without contacting the physician about it. Stopping the drug can cause adverse effects as well.

• If suffering from any underlying medical conditions, such as renal or liver-related problems, inform the physician about it so that they can alter the dosage.

• If you missed a dose, make sure to take it when you remember on the same day. Do not take more than one tablet per day.

• When suffering an allergic reaction or symptoms of overdose, seek medical help immediately.

Things to Do After You Start Taking Emtricitabine and Tenofovir Combination:

Once you start taking the Emtricitabine and Tenofovir combination, look for the changes in symptoms.

• In case of worsening of the symptoms or any adverse effects, inform your doctor so that they can look into what needs to be done.

• Note down if the symptoms have gotten less severe, if there is any change in the symptoms, or if only one particular symptom has improved, or if there is a difference as a whole.

• Keep track of the changes felt after taking the drug and inform the physician, as it plays an important role in deciding if the medication is working and how well the response is.

Look Out for Side Effects:

In patients who have experienced symptoms or allergic reactions to any other drugs or one of these drugs, the drug dose will be altered or substituted by the physician accordingly.

The possible side effects that can occur after taking the Emtricitabine and Tenofovir combination are as given below. Make sure to notice and identify them and report them immediately to the health care provider.

The common side effects of Emtricitabine and Tenofovir when taken as a treatment include;

• Drowsiness or feeling sleepy.

• Nausea.

• Vomiting.

• Diarrhea.

• Depression.

• Sleeping trouble.

• Rash or urticaria.

• Headache.

• Restlessness.

• Weird dreams.

The symptoms that occur when taken as a PrEP include;

• Weight loss.

• Abdominal pain.

• Headache.

These are the most common symptoms; any symptoms other than these can occur as well. When these symptoms occur and do not seem to subside, make sure to get medical help.

There are some other symptoms in the major organs of the body that need medical intervention, such as;

Kidney-Related Symptoms

Usually, patients with any kidney problem should inform priorly to the physician and get the dose altered accordingly. But if an underlying condition is missed, making this drug combination can worsen the kidney-related symptoms. In such cases, inform the physician immediately and get the required tests done.

Bone-Related Symptoms:

These drugs can cause bone thinning and weakening, along with pain, which should be brought to the physician's notice immediately.

Fat Deposition:

There has been fat deposition in the upper body, including the back of the neck, trunk, and breasts, noted in patients under these drugs. Also, some cases have shown loss of fat in the lower part of the body as well.

Immune System-Related Symptoms:

As these drugs strengthen the immune system, there might be symptoms associated with the underlying dormant infections. Make sure to inform the physician.

Dietary Alterations:

As per reports, no dietary alteration is required if a healthy lifestyle is followed already. Make sure to continue the normal diet unless advised for a diet alteration. Also, ensure that the diet is loaded with the required nutrients that favor the immune system.

What Should Be Done When You Miss a Dose?

Missing even a single dose can be crucial for this drug, as the disease progression can become rapid. If one dose is missed, make sure to take it as soon as you remember on the same day.

If it is the next day and already close to the time for your next dose, do not take the tablet twice. The recommended dose is only one tablet per day, so stick to it. If more than one is taken, get your physician's opinion immediately.

What Should Be Done to Treat Emtricitabine and Tenofovir Overdose?

Unfortunately, there is no specific antidote for an overdose of this drug. The overdose of these drugs can cause the buildup of lactic acid in the blood and severe kidney and liver problems.

Inform the physician and call for an ambulance immediately. Make sure to monitor the symptoms and breathing until the ambulance arrives.

How to Store the Emtricitabine and Tenofovir Combination Tablet?

• Emtricitabine and Tenofovir should be stored at an ideal temperature between 20 degrees Celsius/ 68 degrees Fahrenheit and 25 degrees Celsius/ 77 degrees Fahrenheit.

• Do not shift the tablets from their originally sold containers to others. Do not leave the tablet's bottle open.

• Keep it tightly closed. The tablet should be taken out only before consuming it.

• Make sure to keep the bottle away from the reach of kids. Check for already opened or expired drugs before buying; if damaged or expired, do not purchase them.

Avoid Self-Medication:

• As already mentioned, this combination should only be taken after getting a prescription.

• Having this combination of drugs without a prescription could be harmful in multiple ways.

• This medication should not be taken based on any other patient's advice or using another person's prescription as a drug.

• This combination does not work the same for everybody, as the dosage is decided to depend upon the patient's condition and underlying medical conditions.

• When used as a treatment for AIDS, make sure to take the prescribed antiviral drugs along with this combination.

Staying on Track With the Emtricitabine and Tenofovir Combination:

• Take this combination drug regularly and do not stop the drug abruptly without contacting the physician about it. Stopping the drug can cause adverse effects as well.

• Lowering the dose or splitting the tablet in half and taking it is not advisable.

• The improvement in symptoms varies with the person, as there are wide variations in the occurring symptoms as well.

• Results show up quickly in some cases, whereas in other cases it takes some more time.

• Also, do not expect these drugs to cure HIV; they can only slow down the disease and minimize symptoms. Do not get disappointed when such expectations are not satisfied.

For Doctors

Indication:

Emtricitabine and Tenofovir combination is indicated in patients suffering from AIDS as a treatment and as a precautionary drug in patients who are not positive for HIV infection yet fear getting infected with HIV.

Pharmacology

Mechanism of Action:

• Emtricitabine and Tenofovir are two medicines that work together to fight HIV.

• Once they enter the body, Tenofovir disoproxil is changed into its active form, Tenofovir.

• Both medicines then become active with the help of natural enzymes in the body.

• After activation, these drugs block an important enzyme called reverse transcriptase, which HIV needs to make copies of itself. When this enzyme is blocked, the virus cannot finish making its DNA, so it stops multiplying.

• When used together, Emtricitabine and Tenofovir work better than either drug alone. This combined effect helps control HIV more effectively and protects the immune system.

Pharmacodynamics:

These drugs work against HIV by inhibiting the reverse transcriptase enzyme. However, no other data have been provided associated with the pharmacodynamics of this drug combination.

Absorption:

The absorption of Emtricitabine was found to be rapid in mice and rats, with an oral bioavailability of 58 % to 97 %. At the same time, the bioavailability of Tenofovir was found to be around 20 % to 46 %.

Distribution:

Both Emtricitabine and Tenofovir are found to be widely distributed. They cross the placenta but do not cause any effects on the fetus. They were excreted in breast milk. Regarding protein binding, there was only a negligible protein binding observed.

Metabolism:

There was only a limited metabolism of Emtricitabine, whereas Tenofovir disoproxil fumarate was found to be actively converted to Tenofovir when it entered the body.

Elimination:

Tenofovir was excreted unchanged in the urine. Whereas Emricitabine, though said to be excreted unchanged in the urine, data suggest its excretion from the kidneys by active tubular secretion.

Toxicity:

Single doses of Emtricitabine and Tenofovir have shown no known toxicity in animal studies. At the same time, overdose has shown various toxic effects in organs such as the gastrointestinal tract, bone, and the renal tubular epithelium.

Emtricitabine did not cause any genotoxicity, embryotoxic or teratogenic effects, carcinogenicity, or effects on fertility when tested in mice, whereas Tenofovir showed a very rare incidence of carcinogenic effects in the duodenum of mice and was positive for causing forward mutations.

Warning and Precaution

• A history of allergy or reactions to any drugs should be mentioned before getting the prescription.

• Inform about the pregnancy status, planning pregnancy, breastfeeding, planning to breastfeed, etc.

• Habits such as alcohol and drugs, if any, should be mentioned.

• History of medical conditions like renal problems, liver disorders, bone-related disorders, or any other medical conditions, as worsening of the conditions is anticipated.

• Previous history of any infections like Hepatitis B, as it can be reactivated or worsened by this medication.

• This combination has a side effect of building up lactic acid in the blood, called lactic acidosis.

Dosage and Forms

• Emtricitabine and Tenofovir are combination drugs that are formulated together and orally administered.

• It is available in tablet form.

• The average dose is Emtricitabine 200 mg and Tenofovir 300 mg combination. Follow the customized prescription. Do not share prescriptions with others.

• It is available in blue-colored, film-coated, oblong-shaped tablets.

• The tablet is engraved with GILEAD on one side, whereas the other side has 701 engraved on it.

Administration of the Drug

• Emtricitabine and Tenofovir combination should be taken once daily following the instructions and dosage prescribed by the physician.

• It can be taken either before or after food.

• Take the tablet as a whole; do not chew or crush it into powder.

• Swallow the tablet as a whole with water.

• It should be taken at the same time every day.

• Take the dose as prescribed; do not take more or less.

Considerations for Administration:

• Look for the patient's general health by performing blood tests.

• Check the HIV status of the patient to see if the patient needs it as a treatment or as a preventive measure.

• The body weight and age of the patient should be taken into consideration in children.

Contraindications:

Emtricitabine and Tenofovir combination is contraindicated in patients who have,

• Hypersensitivity reactions to the drug.

• Have renal, liver, or bone impairments.

• It is also contraindicated in breastfeeding mothers.

• Children who are 12 years old and younger with a body weight of fewer than 35 kg should not be prescribed this combination drug.

• It should not be administered as a prophylactic drug in patients whose HIV status is not identified or questionable.

Clinical Trials

• An open-label, randomized, multicenter, parallel clinical trial was conducted by the Gilead Sciences company for 48 weeks. It was a Phase IV trial to evaluate the safety and how effectively the Emtricitabine and Tenofovir combination works in treating HIV patients.

• A randomized, double-blind, and parallel study was conducted using 2,499 HIV uninfected males. While the primary outcome focused on analyzing and ruling out anti-HIV seroconversion, the secondary outcome included finding the drug resistance in HIV-positive patients, mineral density of the bone, and STD (sexually transmitted diseases) prevalence. The primary outcome lasted for 36 months, while the secondary outcome lasted for 42 months. The results stated that there was a reduction of about 42 % in the risk of HIV by using this combination as a prophylaxis drug.

• Another randomized, double-blind, parallel trial with 4,758 heterosexual couples was conducted. It was a Phase III clinical trial. In the couple, one partner was HIV-positive while the other was HIV-negative.

Other Specifications

Emtricitabine and Tenofovir Combination in Pregnant Women:

• The use of this drug in pregnant women is still under study. Although, as per the reports gathered now from animal and human studies, no harm has been ruled out.

• Though there is not very appealing data on usage during pregnancy, this drug combination should be taken if there is a definite need for the medication in pregnant women.

• Also, in the case of a woman getting pregnant while taking this combination of drugs as a precaution, the necessity of the drug intake should be ruled out and decided based on the risk factors associated with taking the drug.

• The animal studies on the drugs separately showed no adverse effects as well.

Emtricitabine and Tenofovir Combination in Lactating Women:

• Breastfeeding when the mother is HIV positive is not recommended, as there is a potential risk of HIV transmission to the child.

• Also, Emtricitabine and Tenofovir are excreted, so feeding while on these drugs is not advised, as there might be risks associated.

Emtricitabine and Tenofovir Combination in Pediatric Patients:

• This drug combination should be administered only in children who are 12 years old or more and have a body weight of 35 kilograms or more.

• Children who do not fit this criterion should not be prescribed this combination drug.

Emtricitabine and Tenofovir Combination in Geriatric Patients:

• Clinical studies did not include enough elderly patients, so detailed results in this age group are limited. However, with increasing age, the kidney, liver, heart, and other body functions may not work as efficiently.

• Because of these age-related changes, the dose of Emtricitabine and Tenofovir may need adjustment in older patients.

Emtricitabine and Tenofovir Combination in Patients With Renal Impairment:

• This drug combination is prohibited for use in patients who suffer from serious renal failure or those undergoing dialysis and in patients with a creatinine clearance range of less than 30 ml/minute.

• On using these drugs for pre-exposure prophylaxis (PrEP) against HIV, a creatinine clearance of more than 60 ml/minute is necessary; anyone with a lesser range than this will not be fit to take this drug combination.

Drug Interactions

• This combination medicine should not be used if the patient is already taking certain drugs, because harmful drug interactions have been reported. These include medicines such as Adefovir, Lamivudine, Didanosine (DDL), Atazanavir, Lopinavir, Ritonavir, Cidofovir, Acyclovir, Valacyclovir, Ganciclovir, Valganciclovir, Saquinavir, and Indinavir.

• Patients should also make sure they are not already taking another medicine that contains Emtricitabine or Tenofovir, as this can increase the risk of side effects.

• These are some of the most commonly reported interacting drugs, but they are not the only ones. It is very important to tell the doctor about all medicines being taken, including over-the-counter drugs, supplements, herbal products, and health drinks.

• Patients should inform their doctor about habits like smoking, alcohol use, or recreational drug use, as these can also affect how the medicine works or increase side effects.