Emtricitabine: A Powerful Ally Against HIV Infection

What Is Emtricitabine?

Emtricitabine is a type of HIV medicine called a nucleoside reverse transcriptase inhibitor (NRTI, a medicine that blocks the virus from making more copies of itself). Doctors give this medicine to children and adults to help prevent and treat HIV infection (a virus that weakens the body’s defense system).

It is usually taken once a day by mouth (swallowed as a tablet or liquid) and is often used together with other HIV medicines to work better. Emtricitabine helps by lowering the amount of virus in the blood (viral load, which measures the amount of virus inside the body).

This medicine was approved by the FDA (the organization that checks if medicines are safe) on July 2, 2003. In 2019, it became one of the commonly used HIV medicines, with more than three thousand people getting this prescription.

Drug group:

Nucleoside reverse transcriptase inhibitors (NRTIs) were the first type of HIV medicines approved by the FDA. These drugs usually enter the body in an inactive form called a prodrug (a medicine that becomes active only after the body changes it). Once the drug enters the cell, cellular kinases (special proteins in the cell) change it into its active form so it can start working against the virus.

What Is the Dosage of Emtricitabine?

Emtricitabine is available in two forms and associated strengths. The recommended dosage of Emtricitabine in the treatment of HIV infection includes the following: The form and dosage can vary between the adult and pediatric population, considering weight and certain factors.

• Capsule: 200 milligrams orally once a day.

• Oral solution: 240 milligrams or 24 milliliters orally once daily.

For Patients

How Does Emtricitabine Work?

Emtricitabine works by inhibiting reverse transcriptase, an enzyme the human immunodeficiency virus requires to convert RNA into DNA. Emtricitabine resembles a DNA building block and is incorporated into viral DNA. This prevents the replication of viral DNA. This reduces the number of cells affected by HIV. Emtricitabine, along with other HIV medications, helps treat HIV.

What Are the Things to Inform the Doctor Before Taking Emtricitabine?

• Inform the doctor if one is allergic or hypersensitive to Emtricitabine or other ingredients in the prescribed formulation.

• Tell the doctor about the health status, past medical history, and underlying medical conditions.

• Be sure to inform the doctor of any liver problems, especially hepatitis B virus infection.

• It is crucial to inform the doctor of kidney problems and dialysis treatment.

• Inform the healthcare providers about all the medications one takes or plans to take. This includes prescription medicine, over-the-counter medication, vitamins, nutritional supplements, and herbal products.

• Certain medications are more likely to interact with Emtricitabine, causing undesirable reactions. So, one must keep a list of medications and show it to the healthcare provider before getting treatment.

• Inform the doctor if one is pregnant or has plans to get pregnant. It is not determined whether Emtricitabine could harm the unborn baby. Inform the healthcare provider if one becomes pregnant during the treatment of Emtricitabine.

• There is a pregnancy registry for female patients who take Emtricitabine during pregnancy. This registry is significant because it gathers information about the health status of women and babies.

• Inform the doctor if one is breastfeeding or has any breastfeeding plan. Emtricitabine could be passed to the infant through breast milk. Hence, it is advised not to breastfeed if one has an HIV-1 infection due to the risk of passing the infection to the baby. Discuss with the healthcare provider regarding the safest way to feed the infant.

How Is Emtricitabine Administered?

• Take the Emtricitabine medication precisely as per the healthcare provider's instructions and labeled guidelines.

• Only take in smaller or larger amounts for a shorter time than recommended.

• Emtricitabine medication is advised to be taken by mouth once daily. The dosage differs for adults and children. The form (capsule or oral solution) and dosage for the pediatric population are given based on the healthcare provider’s calculations of the child's weight.

• Emtricitabine medication might be taken with or without food.

• One should take a dose of Emtricitabine. Missing the dosage can lower the amount of medication in the blood. Hence, be cautious and refill the Emtricitabine prescription before anyone runs out of the medicine.

• Do not change the dosage and bring it to a stop taking Emtricitabine without the doctor’s consent. One must stay under the care and supervision of a healthcare provider while on Emtricitabine therapy.

• The disease might become resistant to the Emtricitabine drug if one stops taking the medication, even for the short term.

• One might need frequent blood, liver, and kidney function tests during Emtricitabine treatment.

• Do not take Emtricitabine as the only HIV medicine. Usually, Emtricitabine and Tenofovir is used for PrEP. Human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) are usually targeted with a combination of drugs. So, one should take all the medicines as the healthcare provider directs.

Emtricitabine capsule

• Swallow the Emtricitabine capsule as a whole with water.

• It is advised not to crush, chew, or break the Emtricitabine capsules.

Emtricitabine oral solution

• Measure the oral solution with the dosing syringe provided with the medication or using a specified dose-measuring spatula or medicine cup.

• Then, administer the appropriate dosage of Emtricitabine gradually using a syringe or dispensing tool.

What Are the Side Effects of Emtricitabine?

Emtricitabine is a safe and effective drug for pediatrics, adolescents, and adult populations. It can induce certain undesirable reactions in several people, sometimes requiring medical attention and prompt treatment.

Common emtricitabine side effects

The common side effects associated with Emtricitabine intake are listed below. The following less severe side effects can be temporary and resolved independently. However, one must inform the doctor and get appropriate intervention if it is not cured, disturbing the daily functions.

• Headaches.

• Weakness.

• Dizziness.

• Stomach pain.

• Nausea.

• Vomiting.

• Diarrhea.

• Distorted dreams.

• Abnormal sleep patterns.

• Skin discoloration.

• Rashes.

• Changes in the size and shape of the body part, particularly in the arms, face, legs, breasts, and waist.

Serious emtricitabine side effects

Serious side effects can occur with Emtricitabine treatment. Immediately inform the doctor and receive appropriate and prompt care.

Allergic reaction

Individuals who are allergic or hypersensitive to Emtricitabine can develop specific unwanted reactions.

One must seek professional help if one has the following signs:

• Hives.

• Rashes.

• Difficulty breathing.

• Swelling of the lips, face, and throat.

Lactic acidosis

This form of metabolic disease results when lactic acid accumulates in the blood. The early symptoms associated with this condition could worsen over time, turning fatal. Hence, one should get medical help with even milder symptoms.

• Muscle pain or weakness.

• Difficulty breathing.

• Nausea and vomiting.

• Stomach pain.

• Numbness or cold feelings in the extremities.

• Rapid or abnormal heart rate.

• Dizziness.

• Tiredness.

Liver problems

Inform the doctor if one has any symptoms of a liver problem.

They include:

• Upper stomach pain.

• Swelling around the midsection of the abdomen.

• Dark urine.

• Loss of appetite.

• Nausea.

• Jaundice (yellowish discoloration of the skin and mucous membrane).

Emtricitabine might increase the risk of autoimmune disorders and certain infections by influencing the mechanism of the immune system. One could experience the symptoms in weeks or months following the initiation of Emtricitabine therapy.

The signs include the following.

• Signs of a new infection include night sweats, fever, mouth sores, swollen glands, stomach pain, diarrhea, and weight loss.

• Chest pain during breathing, wheezing, dry cough, and shortness of breath.

• Cold sores, sores on the anal or genital area.

• Rapid heart rate, irritability, weakness, balance problems, and problems with eye movement.

• Difficulty speaking, lower back pain, loss of bladder control.

• Swelling in the neck or throat, impotence, menstrual changes, and loss of interest in sex.

Dietetic and Other Restrictions

You can continue your normal diet unless your doctor tells you otherwise. Remember that taking Emtricitabine does not completely stop you from spreading HIV to others. You should avoid unprotected sex and never share razors or toothbrushes, as these can spread infection.

Talk to your doctor about safe ways to prevent HIV transmission during sex. Also, never share needles or drug equipment, as this is unsafe for everyone, even people without HIV.

Missed dose

One can take the missed dosage as soon as one has the thought. However, skip the missed dosage if it is nearly time for the subsequent dose of Emtricitabine. One should not take the double dosage of Emtricitabine medication to compensate for the forgotten dose.

Overdose:

In case of overdosage, seek emergency medical services or the poison helpline at the earliest. Call the healthcare provider or reach out to the nearest emergency room straight away if one takes too much Emtricitabine.

Overdosage of Emtricitabine can cause serious effects, sometimes resulting in death. The healthcare professionals will monitor the individual for evidence of toxicity and start with a standard supportive intervention as required.

Storage:

• Keep the Emtricitabine medication in its original packaging and keep the container firmly closed.

• Do not use the Emtricitabine medication if the seal over the container opening is missing or broken.

• Keep the Emtricitabine medication away from heat, sunlight, and moisture. Any medication should be stored away from the sight and reach of children.

• Emtricitabine capsules should be stored at a room temperature of 68 to 77 degrees Fahrenheit.

• Emtricitabine oral solution should be stored in the refrigerator at 36 to 46 degrees Fahrenheit.

• One might also store Emtricitabine at room temperature within 68 to 77 degrees Fahrenheit, for up to three months.

For Doctors

Clinical data of Emtricitabine

• Drug name: Emtricitabine.

• Generic name: Emtricitabine.

• Route of administration: Oral.

• Drug class: Nucleoside reverse transcriptase inhibitors (NRTIs).

• Molar mass: 247.24 g/mol -1.

• Chemical formula: C8H10FN3O3S.

Indication (Emtricitabine uses):

Emtricitabine, in combination with other medications, is indicated in the following conditions:

• Treatment of human immunodeficiency virus (HIV)-1 infection.

• Treatment of HIV-1 infection in pediatric populations of 25 to 35 kg.

• Treatment of HIV-1 disease in adults weighing greater than 35 kg.

• Emtricitabine is safe for PrEP - pre-exposure prophylaxis of HIV-1 in both adolescents and adults, except for those having receptive vaginal sex.

• Treatment of HIV-1 infection in children and adults weighing greater than 17 kg.

• Pre-exposure prophylaxis in both adolescents and adults is more significant than 35 kg.

• Treatment of HIV-1 infection in individuals greater than 12 years, weighing more than 35 kg, 25 kg, and 40 kg.

Associated conditions:

• HIV transmission.

• Human immunodeficiency virus (HIV) infections.

• Human immunodeficiency virus type 1 infection.

• Pre-exposure prophylaxis.

Dose:

Testing the patients before the initiation of Emtricitabine treatment is required. So, test them for hepatitis B virus infection before the initial dosage. Emtricitabine is advised to be taken by mouth without regard to food. It is usually taken once daily.

Pediatric patients (0 to 3 months of age):

• The recommended dosage for the capsule form is one 200 mg (milligrams) capsule once daily orally.

• For oral solution form, the recommended dosage of Emtricitabine is 240 mg (24 milliliters) once daily orally.

Pediatric patients (3 months through 17 years):

• The recommended dosage for the oral solution form is 3 mg per kg once daily.

Adult patients:

• For oral solution form, the recommended dosage is 6 mg per kilogram up to a maximum range of 240 mg (24 milliliters) once daily orally.

• For Emtricitabine capsules, one 200 mg capsule once daily orally is recommended for pediatric patients weighing over 33 kilograms who can swallow the intact capsule.

Dosing considerations:

The following dosing adjustments are considered in various stages associated with renal impairment.

• For creatinine clearance of 50 mL/min or more, take a 200 mg capsule once daily or a 240 mg oral solution once daily.

• Creatinine clearance of 30 to 49 mL/min, 200 mg orally once every 48 hours; 120 mg oral solution once daily.

• Creatinine clearance of 15 to 29 mL/min, 200 mg orally once in 72 hours; 80 mg oral solution once daily.

• Creatinine clearance of less than 15 mL/min, 200 mg capsule orally once in 96 hours; 60 mg oral solution once daily.

• Emtricitabine administration on the day of hemodialysis is always recommended after dialysis.

What Are the Pharmacological Aspects of Emtricitabine?

Pharmacodynamics:

Emtricitabine is typically a cytidine analog that competes with the natural substrate of the human immunodeficiency virus (HIV) -1 reverse transcriptase to be integrated into a new deoxyribonucleic acid (DNA), resulting in the termination of its transcription. Emtricitabine is generally administered once daily, so its duration of action is prolonged. It is recommended that patients be cautioned about the risks associated with lactic acidosis and hepatomegaly.

Mechanism of action:

Emtricitabine is a cytidine analog that generally competes with the deoxycytidine 5-triphosphate intended for HIV-1 reverse transcripts after being phosphorylated to Emtricitabine 5-triphosphate. Since HIV-1 reverse transcriptase integrates Emtricitabine with the newly formed DNA strands, new nucleotides can not be incorporated.

This results in the termination of the viral DNA chain. In addition, reverse transcriptase inhibition circumvents viral ribonucleic acid (RNA) transcription into DNA. Hence, the virus loses the potential to incorporate its DNA with the host DNA, replicating the host cell machinery. As a result, the virus load is reduced.

Pharmacokinetics:

Absorption:

• Emtricitabine attains a maximum peak serum concentration (Cmax) of 1.8 mg/mL with a time-to-peak concentration of one to two hours.

• The area under the curve (AUC) of Emtricitabine is determined to be 10mg*hr/mL.

• The bioavailability of Emtricitabine capsules is about 93 percent, and that of the oral solution form is 75 percent.

• Intake of Emtricitabine with food could decrease the Cmax by 29 percent.

Distribution:

• The evident central volume of distribution of Emtricitabine is 42.3 liters, and the peripheral volume of distribution is around 55.4 liters.

• The plasma protein binding capacity of Emtricitabine is four percent.

• Emtricitabine binds chiefly with serum albumin.

Metabolism:

• Emtricitabine is not adequately metabolized. So, it is approximately 86 percent unmetabolized.

• Nearly nine percent of the dosage is metabolized to form 3-sulfoxide diastereomers, four percent into 2-O-glucuronide, and a minor proportion converts into 5-fluorocytosine.

Elimination:

• Nearly 86 percent of Emtricitabine is recovered in urine and 14 percent in feces.

• About 13 percent of the dosage is recovered in the urine through metabolites, nine percent as 3-sulfoxide diastereomers, and four percent as 2-O-glucuronide.

Half-life and clearance:

• The half-life period of Emtricitabine is nearly ten hours.

• Emtricitabine has an evident elimination rate of 15.1 liters/hour.

• The rate of elimination of Emtricitabine is closely related to creatinine clearance.

Toxicity:

• The median lethal dose (LD50) of the drug Emtricitabine is not readily available.

• The symptoms of toxicity of Emtricitabine include lactic acidosis as well as hepatotoxicity with steatosis.

• The treatment of overdosage includes symptomatic and supportive measures, encompassing hemodialysis.

Adverse effects:

Emtricitabine can cause adverse effects. The following are the potential adverse effects based on the frequencies of the combination treatment.

Greater than 10 percent:

• Diarrhea.

• Headache.

• Dizziness.

• Rash.

• Insomnia.

• Nausea.

• Asthenia.

• Abdominal pain.

• Abnormal sleep patterns and dreams.

• Rhinitis.

• Increased creatinine kinase.

• Neuritis.

• Paresthesia.

• Cough.

One to ten percent:

• Dyspepsia.

• Symptoms associated with depression.

• Myalgia.

• Increased triglyceride levels.

• Vomiting.

Less than one percent:

• Severe lactic acidosis.

• Hepatomegaly with steatosis, even in fatal cases.

• Severe and acute exacerbation of hepatitis B in individuals with co-infection of HIV-1 and Hepatitis B virus infection.

What Are the Contraindications of Emtricitabine?

The drug Emtricitabine is strictly contraindicated in individuals with hypersensitivity to Emtricitabine and any other components of the product.

Warnings and precautions:

HBV infection:

Every patient with HIV-1 infection should be tested for the manifestation of chronic hepatitis B virus (HBV) infection before the initiation of antiretroviral therapy. The safety and efficacy of Emtricitabine have not been established in people with coinfection of HIV-1 and HBV. For people infected with HBV, exacerbations of hepatitis B were noticed in association with liver dysfunction and liver failure when treated with Emtricitabine.

Hence, hepatic function should be closely monitored with laboratory and clinical follow-ups for a minimum of several months in people who are coinfected with both HBV and HIV-1. Discontinue the therapy if there is any change. Initiation of anti-hepatitis B treatment might be warranted if appropriate.

Lactic acidosis and hepatomegaly:

The clinical findings show the incidence of lactic acidosis and severe degrees of hepatomegaly with steatosis, even with fatal incidents when using nucleoside analogs, either solely or in combination with other antiretroviral drugs.

It is recommended that the treatment be suspended in any individual developing clinical or laboratory manifestations suggestive of lactic acidosis or hepatotoxicity. Hepatotoxicity includes hepatomegaly and steatosis even without significant transaminase elevation.

Coadministration:

It should not be co-administered with the specified combination of antiretroviral agents constituting Lamivudine or Emtricitabine.

Renal function:

Depending on the creatinine clearance rate, dosage adjustment and reduction are recommended in people with impaired renal function.

Immune reconstitution syndrome:

The risk and occurrence of immune reconstitution syndrome when combined with certain other antiretroviral drugs have been reported. The autoimmune disorders determined include polymyositis, Grace’s disease, and Guillain-Barré syndrome.

Such problems have been reported to manifest in the setting of immune reconstitution. Nevertheless, the onset time is variable, occurring many months after initiating Emtricitabine therapy.

Specific considerations:

• Geriatrics: The data do not provide adequate evidence showing the effect of Emtricitabine on geriatric patients. It is not determined whether the geriatric population responds differently from adults. Generally, dosage selection for elderly patients should be made cautiously, considering the greater risk and frequency of renal, hepatic, and cardiac dysfunctions, concomitant conditions, and other drug treatments.

• Pregnancy: The clinical data from the registry show that there is no increase in the overall risks of significant birth defects with the very first-trimester exposure to Emtricitabine. However, Emtricitabine should be prescribed considering the potential benefits and risks to the mother and the unborn baby.

• Lactation: It is recommended that HIV-1-infected women should not breastfeed to prevent the risk of postnatal transmission of HIV-1 infection. Hence, instruct mothers not to breastfeed during Emtricitabine treatment due to the risk of passing the virus into the infant.

• Renal impairment: Modification of the dosage and dosing interval of Emtricitabine is recommended for people with creatinine clearance of less than 59 milliliters per minute and people with end-stage renal disorder requiring hemodialysis.