Efavirenz / Emtricitabine / Tenofovir Disoproxil Fumarate
Mylan-Efavirenz/Emtricitabine/Tenofovir Disoproxil Fumarate
- Dosage form
- Tablet
- Available strengths
- 600 mg efavirenz / 200 mg emtricitabine / 300 mg tenofovir disoproxil fumarate
- Drug class
- Non-nucleoside reverse transcriptase inhibitor (NNRTI) plus two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) combination (antiretroviral)
- Common brand
- Mylan-Efavirenz/Emtricitabine/Tenofovir Disoproxil Fumarate
Clinical overview. This medicine combines efavirenz, an NNRTI, with emtricitabine and tenofovir disoproxil fumarate, two NRTIs, in a single once-daily antiretroviral tablet used to treat HIV-1 infection in adults. It must be taken on an empty stomach, ideally at bedtime, since food increases efavirenz absorption and can worsen nervous system side effects like dizziness and vivid dreams. It has numerous significant drug interactions, can reduce the effectiveness of hormonal contraceptives, and carries warnings for liver toxicity, kidney problems, and psychiatric side effects.
Indication
Common therapeutic uses
- This medicine treats HIV-1 infection in adults, either used alone as a complete regimen or combined with other antiretroviral agents.
- It is not approved to treat chronic hepatitis B infection, even though two of its components are also active against hepatitis B virus.
Pregnancy
Risk assessment and monitoring considerations
- Efavirenz may cause fetal harm when taken during the first trimester, so pregnancy should be avoided while on this medicine and for 12 weeks after stopping it.
- A barrier method of contraception must always be used together with another method, such as hormonal contraception, since efavirenz can reduce the effectiveness of hormonal birth control.
- Women who could become pregnant should have a pregnancy test before starting this medicine.
- This medicine should only be used in pregnancy if the potential benefit outweighs the potential risk to the fetus, such as when there is no other treatment option.
- Rare reports of neural tube defects have been described in babies exposed to efavirenz-containing regimens in the first trimester, though a direct causal link has not been established.
Breastfeeding
Infant exposure considerations
- Mothers with HIV should not breastfeed while taking this medicine, primarily to avoid passing HIV to the infant.
- Efavirenz, emtricitabine, and tenofovir all pass into breast milk, and nursing infants may be at risk of developing viral resistance or other adverse effects.
Geriatrics
Dosing and tolerability considerations
- Clinical studies did not include enough patients aged 65 and older to know whether they respond differently than younger adults; dose selection should be cautious given the greater likelihood of reduced liver, kidney, or heart function in this age group.
Pediatrics
Use in children and adolescents
- Safety and effectiveness have not been established in patients under 18 years of age, so this medicine is not recommended for pediatric use.
Dosage & Administration
Practical dosing and administration
- The recommended dose is one tablet (600 mg efavirenz / 200 mg emtricitabine / 300 mg tenofovir) taken by mouth once daily on an empty stomach.
- Taking the dose at bedtime can improve tolerability of nervous system side effects such as dizziness or vivid dreams.
- Because this is a fixed-dose tablet whose individual components cannot be separated, it should not be used in patients with moderate to severe kidney impairment (creatinine clearance under 50 mL/min).
- This medicine is not recommended in patients with moderate or severe liver impairment, and should be used cautiously with careful monitoring in mild liver impairment.
- If a dose is missed and remembered the same day, it should be taken right away; never take more than one dose in a single day.
Overdose
Recognizing and responding to overdose
If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.
- Overdose experience is limited; some patients who accidentally took twice the recommended efavirenz dose reported increased nervous system symptoms, involuntary muscle contractions, or vomiting.
- There is no specific antidote for efavirenz overdose.
- Activated charcoal may help remove unabsorbed efavirenz from the gut.
- Emtricitabine and tenofovir can be removed to some extent by hemodialysis, but efavirenz is highly protein-bound and is not expected to be significantly removed by dialysis.
- Management is supportive, with monitoring of vital signs and clinical status.
Common side effects
Frequently reported tolerability concerns
- Dizziness may occur, often within the first days of treatment.
- Vivid or abnormal dreams may occur.
- Nausea may occur.
- Diarrhea may occur.
- Headache may occur.
- Fatigue may occur.
- Trouble sleeping (insomnia) may occur.
- Drowsiness (somnolence) may occur.
- Skin rash may occur, usually within the first two weeks of treatment.
- Upper respiratory infections and sinus infections may occur more often.
Serious side effects
Findings that may require urgent assessment
Serious side effects require immediate discussion with the prescriber or emergency care.
- Lactic acidosis and severe enlargement of the liver with fatty change, including fatal cases, have been reported with the tenofovir component.
- Serious liver problems, including liver failure, have occurred, sometimes in people without pre-existing liver disease.
- Severe skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, can occur; treatment should be stopped immediately if severe rash develops with blistering, peeling, or fever.
- Serious psychiatric reactions, including severe depression, suicidal thoughts, aggressive behaviour, and, rarely, psychosis, have been reported.
- Seizures have occurred, more often in patients with a prior seizure history.
- Kidney problems, including acute kidney failure and Fanconi syndrome (a kidney condition causing loss of phosphate, glucose, and other substances in the urine), have been reported with the tenofovir component.
- Decreases in bone mineral density have been observed with long-term tenofovir use.
- Immune reconstitution inflammatory syndrome can occur as the immune system recovers, triggering inflammation from hidden infections or autoimmune conditions.
- Sudden worsening of hepatitis B has been reported in patients coinfected with HIV and hepatitis B after stopping this medicine, so liver function should be monitored closely for several months after discontinuation in these patients.
- Seek urgent medical attention for severe rash, yellowing of the skin or eyes, unusual muscle pain with weakness, difficulty breathing, or thoughts of self-harm.
Use with caution
Situations requiring closer assessment
- Use with caution in patients with underlying liver disease, including hepatitis B or C coinfection, due to the risk of worsening liver function.
- Use with caution in patients with a history of seizures or who take other medicines that lower the seizure threshold.
- Use with caution in patients with a history of psychiatric illness, and monitor closely for new or worsening depression, anxiety, or unusual thoughts.
- Use with caution in patients with risk factors for kidney disease, and check kidney function before starting and periodically during treatment.
- Use with caution in patients with a history of bone fracture or osteoporosis risk, since tenofovir can reduce bone mineral density.
- Use with caution in patients switching from a protease-inhibitor-based regimen, since virologic response may be lower and closer monitoring is warranted.
- Avoid concurrent use of other nephrotoxic drugs, such as aminoglycosides, amphotericin B, or vancomycin, because of the added kidney risk from tenofovir.
- Alert patients to the added risk of central nervous system effects when this medicine is combined with alcohol or other psychoactive drugs.
Contraindications
Situations where therapy may be inappropriate
- Contraindicated in patients with known hypersensitivity to efavirenz, emtricitabine, tenofovir disoproxil fumarate, or any ingredient in the tablet.
- Contraindicated with certain antiarrhythmics, such as bepridil, due to the risk of serious heart rhythm problems.
- Contraindicated with the hepatitis C combination elbasvir/grazoprevir, due to a significant loss of effectiveness of that treatment.
- Contraindicated with voriconazole, since each drug significantly changes the blood levels of the other.
- Contraindicated with certain antihistamines (astemizole, terfenadine) and the GI motility drug cisapride, due to the risk of serious heart rhythm problems.
- Contraindicated with ergot-derived migraine medicines, due to the risk of severe vasospasm and reduced blood flow to the extremities.
- Contraindicated with the sedatives midazolam and triazolam, due to the risk of prolonged sedation or slowed breathing.
- Contraindicated with the antipsychotic pimozide, due to the risk of serious heart rhythm problems.
- Contraindicated with St. John's wort, since it can significantly lower efavirenz levels and lead to loss of viral control.
Drug interactions
Clinically relevant combinations
- Other HIV protease inhibitors, including atazanavir and indinavir, can have significantly altered blood levels when combined with this medicine, and some combinations are not recommended.
- Certain hepatitis C antiviral regimens, including glecaprevir/pibrentasvir, can have reduced effectiveness when combined with this medicine and are not recommended together.
- Rifampin lowers efavirenz levels and generally requires an increased efavirenz dose; rifabutin levels are reduced and usually require an increased rifabutin dose.
- Methadone levels can drop significantly, sometimes causing withdrawal symptoms, so the methadone dose may need to be increased.
- Warfarin levels can be increased or decreased, so more frequent monitoring of blood clotting tests is needed.
- Immunosuppressants such as cyclosporine, tacrolimus, and sirolimus can have reduced blood levels, requiring closer monitoring and possible dose adjustment.
- Sertraline levels can be reduced, sometimes requiring a higher sertraline dose.
- Hormonal contraceptives can have reduced effectiveness, so a reliable barrier method must always be used in addition.
- Other enzyme-inducing or enzyme-affected drugs metabolized through the same liver pathways as efavirenz may need dose adjustment; a pharmacist should review the full medication list before starting this medicine.
Food interactions
Meal-related administration
- This medicine should be taken on an empty stomach; taking it with a high-fat meal significantly increases efavirenz absorption and can worsen nervous system side effects such as dizziness and vivid dreams.
Time of administration
Practical scheduling
- Take this medicine once daily on an empty stomach, ideally at bedtime, to help reduce dizziness, vivid dreams, and other nervous system side effects.
Storage
Product handling
- Store at 15°C to 30°C in the original container, tightly closed.
- Do not use if the seal over the bottle opening is broken or missing.
Patient take-away
Key counselling points for a quick closing summary
- This medicine is a three-drug combination that treats HIV-1 infection and must be taken every day, on an empty stomach, exactly as prescribed, without missing doses.
- Taking it at bedtime can make dizziness, vivid dreams, and other nervous system effects easier to tolerate.
- Tell your healthcare professional about every other medicine you take, including birth control, since this medicine has many significant drug interactions and can make hormonal contraceptives less effective.
References
Source material and product information
For professional reference. Confirm patient-specific decisions against the current approved product monograph and applicable clinical guidance.