Fostemsavir

Fostemsavir is a prescription medication used in combination with other antiretroviral drugs for the treatment of HIV-1 infection in heavily treatment-experienced adults with multidrug-resistant HIV-1 infection failing their current antiretroviral treatment regimen owing to resistance, intolerance, or safety considerations. 

• Fostemsavir is available under the following different brand names: Rukobia.

Common side effects of Fostemsavir include:

• nausea
• diarrhea
• headache
• abdominal pain
• indigestion/heartburn
• fatigue
• rash
• sleep disturbance
• immune reconstitution inflammatory syndrome
• drowsiness
• vomiting

Serious side effects of Fostemsavir include:

• hives
• difficult breathing 
• swelling of the face, lips, tongue, or throat
• fast/irregular heartbeat
• severe dizziness
• faintings

Rare side effects of Fostemsavir include:

• none 

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, coordination loss, unsteady, very stiff muscles, high fever, profuse sweating, or tremors.
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.
• Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult dosage

Tablet, extended-release

• 600 mg

HIV Infection

Adult dosage

• 600 mg orally two times a day

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, healthcare provider, or pharmacist first.

• Fostemsavir has severe interactions with at least 23 other drugs
• Fostemsavir has serious interactions with at least 21 other drugs
• Fostemsavir has moderate interactions with at least 204 other drugs
• Fostemsavir has minor interactions with no other drugs

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, health questions, or concerns.

Contraindications

• Hypersensitivity to fostemsavir or any of its components
• Coadministered strong CYP3A inducers (eg, enzalutamide, carbamazepine, phenytoin, rifampin, mitotane, St John’s wort), as significant decreases in temsavir (the active moiety of fostemsavir) plasma concentrations may occur, which may result in loss of virologic response

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Fostemsavir?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Fostemsavir?”

Cautions

• Immune reconstitution syndrome reported with combination antiretroviral therapy; an inflammatory response to indolent or residual opportunistic infections (eg, Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia, or tuberculosis) may occur, which may necessitate further evaluation and treatment; autoimmune disorders (eg, Grave disease, polymyositis, Guillain-Barre) also reported
• Monitor liver enzymes in patients coinfected with hepatitis B or C virus; elevated hepatic transaminases observed in a greater proportion of coinfected individuals; maintain/initiate effective hepatitis B therapy when initiating fostemsavir to avoid hepatitis B reactivation
• Drug interaction overview
  • CYP3A4 inducers
    • Contraindicated
  • Temsavir (active moiety) is a CYP3A4 substrate
  • Coadministration with strong CYP3A4 inducers significantly decreases temsavir plasma concentrations, which may lead to loss of virologic response and resistance
• QT prolongation
  • Caution with a history of prolonged QT, torsade de Pointes, or cardiac disease prone to arrhythmias
  • Caution if coadministered with other drugs known to prolong QT interval
  • QTc prolongation reported with higher than recommended doses
  • Geriatric patients may be more prone to QT prolongation
• OATP and BCRP substrates
  • Temsavir inhibits OATP1B1, OATP1B3, and BCRP
  • Caution; OATP1B1/3 or BCRP substrates (eg, grazoprevir, voxilaprevir, ethinyl estradiol, statins) may need to be avoided or require dosage modification
  • Temsavir inhibits OATP)1B1/3, which may increase plasma concentration of substrate

Pregnancy and Lactation

• Antiretroviral pregnancy registry: Clinicians are encouraged to register patients by calling 1-800-258-4263
• Human data are insufficient regarding use during pregnancy to adequately assess a drug-associated risk of birth defects and miscarriage
• Lactation
  • The CDC recommends that HIV-1–infected mothers in the US not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection
  • Unknown if excreted in breast milk, affects milk production, or breastfed infants