Rukobia (Fostemsavir)
HIV-1 Attachment Inhibitor — Extended-Release Tablets
Quick Facts About Rukobia
Key Takeaways About Rukobia
- Novel mechanism of action: Rukobia is the first and only attachment inhibitor, blocking HIV at the earliest stage of viral entry by targeting gp120
- For treatment-experienced patients: Specifically approved for adults with multidrug-resistant HIV who have limited remaining treatment options
- Must be combined with other antiretrovirals: Rukobia is always used as part of combination antiretroviral therapy, never as monotherapy
- Swallow tablets whole: Extended-release tablets must not be chewed, crushed, or split to maintain proper drug release
- Important drug interactions: Cannot be combined with strong CYP3A inducers such as rifampicin, carbamazepine, or St. John’s wort
What Is Rukobia and What Is It Used For?
Rukobia (fostemsavir) is a first-in-class HIV-1 attachment inhibitor used in combination with other antiretroviral medicines to treat HIV-1 infection in adults who have exhausted multiple prior treatment regimens and have limited remaining therapeutic options.
Rukobia contains the active substance fostemsavir, which belongs to a novel class of antiretroviral medicines known as attachment inhibitors. Unlike other antiretroviral drug classes that target the virus after it has entered the host cell, fostemsavir works at the very first step of viral entry by binding directly to the gp120 subunit of the HIV-1 envelope glycoprotein. This binding prevents the conformational changes needed for the virus to attach to the CD4 receptor on host immune cells, effectively blocking viral entry before it can begin.
Fostemsavir is actually a prodrug — once ingested, it is rapidly converted in the body to its active form, temsavir. Temsavir is the compound that directly binds to gp120 and exerts the antiviral effect. This prodrug approach was developed to improve the oral bioavailability and pharmacokinetic profile of the active compound, allowing for convenient twice-daily dosing.
The unique mechanism of action of Rukobia makes it particularly valuable for patients with multidrug-resistant HIV-1. Because it targets a different step in the viral lifecycle and a different protein than all other approved antiretroviral classes (including NRTIs, NNRTIs, protease inhibitors, integrase inhibitors, CCR5 antagonists, and fusion inhibitors), Rukobia can retain activity against HIV strains that have developed resistance to these conventional agents. This represents a critical advance for the most vulnerable HIV-positive patients who have run out of treatment options.
Rukobia does not cure HIV infection. It reduces the amount of virus (viral load) in the body and keeps it at a low level. By suppressing viral replication, Rukobia helps the immune system recover, as evidenced by increases in CD4+ T cell counts. CD4+ T cells are the white blood cells that play a central role in the body’s ability to fight infections. You must continue taking Rukobia every day as prescribed to maintain viral suppression.
Rukobia was first approved by the U.S. Food and Drug Administration (FDA) in July 2020 and subsequently received marketing authorization from the European Medicines Agency (EMA) in February 2021. The approval was based primarily on data from the pivotal BRIGHTE trial (Study 205888), a Phase III, partially randomized, multicenter study in heavily treatment-experienced adults with multidrug-resistant HIV-1. In this landmark trial, patients who received Rukobia plus an optimized background regimen demonstrated significant and durable improvements in viral suppression and CD4+ cell counts through 96 weeks of follow-up.
What Should You Know Before Taking Rukobia?
Before starting Rukobia, inform your doctor about all medical conditions, especially heart problems and liver disease. Certain medications are strictly contraindicated with Rukobia. Do not take Rukobia if you are allergic to fostemsavir or any of its ingredients.
Contraindications
You must not take Rukobia if you are allergic (hypersensitive) to fostemsavir or any of the other ingredients in the medicine. You must also avoid Rukobia if you are currently taking any of the following medications, as they significantly reduce fostemsavir levels in the blood and can make Rukobia ineffective:
- Carbamazepine or phenytoin — used to treat epilepsy and prevent seizures. These are potent CYP3A inducers that dramatically lower temsavir exposure.
- Mitotane — used for the treatment of several types of cancer, particularly adrenocortical carcinoma. This drug is a strong enzyme inducer.
- Enzalutamide — used for the treatment of prostate cancer. Like the above agents, it induces hepatic metabolism to an extent that renders fostemsavir ineffective.
- Rifampicin — used for the treatment of certain bacterial infections, including tuberculosis. Rifampicin is one of the most potent known CYP3A inducers and drastically reduces temsavir plasma concentrations.
- Products containing St. John’s wort (Hypericum perforatum) — a traditional herbal remedy used for mild depression and anxiety. Despite being a natural product, St. John’s wort is a clinically significant enzyme inducer that can compromise antiretroviral therapy.
If you are taking any of the above medications, do not start Rukobia until you have spoken with your doctor. Stopping these medications abruptly may also have consequences, so your doctor will need to plan any transitions carefully.
Warnings and Precautions
Before starting Rukobia, it is essential that your doctor knows about certain conditions that may require additional monitoring or caution:
Heart conditions: Rukobia can affect heart rhythm, specifically causing QT interval prolongation on electrocardiogram (ECG). If you have or have ever had heart problems, or if you notice any abnormal changes in your heartbeat (such as unusually fast or slow heartbeat, palpitations, or fainting), inform your doctor immediately. This is particularly important if you are also taking other medications that are known to prolong the QT interval, such as amiodarone, sotalol, or quinidine.
Liver disease: If you have or have had liver disease, including hepatitis B or hepatitis C, tell your doctor before starting Rukobia. Liver function may need to be monitored more closely, as the metabolism of fostemsavir involves hepatic processing. Patients with pre-existing liver conditions may be at increased risk of hepatic adverse events.
Immune Reconstitution Inflammatory Syndrome (IRIS): When people with advanced HIV infection (AIDS) begin antiretroviral treatment, their immune system starts to recover and may begin fighting infections that were previously hidden or dormant. This can cause symptoms of infection and inflammation to appear or worsen, even though you are being treated for HIV. In some cases, the recovering immune system may also mistakenly attack healthy tissue (autoimmune disorders), which can occur several months after starting HIV treatment. Symptoms may include muscle weakness, joint pain or swelling, weakness that begins in the hands and feet and moves upward, palpitations, tremor, or hyperactivity. If you experience any of these symptoms, tell your doctor immediately.
Regular blood tests: While taking Rukobia, your doctor will arrange regular blood tests to measure the amount of HIV in your blood (viral load) and to monitor for potential side effects. These blood tests are essential for ensuring that the treatment is working effectively and that you remain in good health.
Children and adolescents: Rukobia is not recommended for patients under 18 years of age, as it has not been studied in this age group. Safety and efficacy data are only available for adult patients.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, or are planning to have a baby, consult your doctor before taking Rukobia. Your doctor will discuss the potential benefits and risks to both you and your baby. The decision to use Rukobia during pregnancy should be made on an individual basis, weighing the need for effective HIV treatment against any potential risks.
Breastfeeding is not recommended for women living with HIV, regardless of whether they are taking Rukobia, because HIV infection can be transmitted to the child through breast milk. It is also not known whether the ingredients in Rukobia can pass into breast milk. If you are breastfeeding or considering breastfeeding, discuss this with your doctor as soon as possible to explore safe alternatives for infant feeding.
Driving and Using Machines
Rukobia may cause dizziness, somnolence, and other side effects that could reduce your alertness and reaction time. Do not drive or operate machinery until you know how Rukobia affects you personally. If you experience these side effects, avoid activities that require full attention until the symptoms resolve.
How Does Rukobia Interact with Other Drugs?
Rukobia has significant drug interactions with several medication classes. Some drugs are absolutely contraindicated, while others may require dose adjustments or additional monitoring. Always inform your doctor and pharmacist about all medicines you are taking.
Drug interactions with Rukobia are clinically important because fostemsavir and its active metabolite temsavir are substrates of CYP3A4 and other metabolic pathways. Strong inducers of CYP3A can dramatically lower temsavir levels, rendering Rukobia ineffective. Conversely, Rukobia can affect the levels of certain other drugs in the body, potentially increasing the risk of their side effects or altering their efficacy.
Major Interactions (Contraindicated)
| Medication | Used For | Reason |
|---|---|---|
| Carbamazepine | Epilepsy, seizure prevention | Strong CYP3A inducer; dramatically reduces temsavir levels |
| Phenytoin | Epilepsy, seizure prevention | Strong CYP3A inducer; dramatically reduces temsavir levels |
| Rifampicin | Tuberculosis, bacterial infections | Potent CYP3A inducer; renders Rukobia ineffective |
| Mitotane | Adrenocortical cancer | Strong enzyme inducer; unacceptable reduction in drug levels |
| Enzalutamide | Prostate cancer | Strong CYP3A inducer; significantly reduces temsavir exposure |
| St. John’s wort | Mild depression, anxiety (herbal) | Clinically significant enzyme inducer; compromises efficacy |
Not Recommended
Elbasvir/grazoprevir (used for hepatitis C infection) is not recommended in combination with Rukobia due to the potential for altered drug levels that could compromise the safety or efficacy of either treatment. If you require hepatitis C treatment while taking Rukobia, your doctor will need to select an alternative hepatitis C regimen.
Interactions Requiring Monitoring or Dose Adjustment
The following medications may interact with Rukobia and may require your doctor to adjust doses or increase monitoring:
| Medication | Used For | Clinical Concern |
|---|---|---|
| Amiodarone, disopyramide, ibutilide, procainamide, quinidine, sotalol | Heart rhythm disorders | Additive QT prolongation risk when combined with Rukobia |
| Statins (atorvastatin, fluvastatin, pitavastatin, rosuvastatin, simvastatin) | High cholesterol | Rukobia may increase statin levels, raising the risk of muscle-related side effects (myopathy) |
| Ethinylestradiol | Oral contraceptives | Rukobia may increase ethinylestradiol levels; monitor for estrogen-related side effects |
| Tenofovir alafenamide (TAF) | Antiviral (often used in HIV combination therapy) | Potential for altered TAF levels; clinical significance under evaluation |
This is not a complete list of all possible drug interactions. Always tell your doctor or pharmacist about every medication you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements. Your doctor can determine whether any adjustments are needed and will monitor your treatment accordingly.
What Is the Correct Dosage of Rukobia?
The standard dosage of Rukobia is one 600 mg extended-release tablet taken twice daily (every 12 hours), with or without food. Tablets must be swallowed whole — do not chew, crush, or split them.
Always take Rukobia exactly as your doctor has instructed. If you are unsure about any aspect of your dosing, consult your doctor or pharmacist for clarification. Adherence to your prescribed regimen is critical for maintaining viral suppression and preventing the development of drug resistance.
Adults
Standard Adult Dosage
Dose: 600 mg (one tablet) twice daily
Route: Oral
With food: Can be taken with or without food
Administration: Swallow whole with a small amount of liquid. Do not chew, crush, or split the tablet. Breaking the tablet may cause the drug to be released too quickly in the body, which could lead to increased side effects or altered drug levels.
Children and Adolescents
Rukobia is not recommended for patients under 18 years of age. There are currently no clinical data to support the use of fostemsavir in pediatric populations. Studies in children and adolescents have not been conducted, and appropriate dosing in these age groups has not been established. If an adolescent requires a salvage antiretroviral regimen, alternative agents with pediatric data should be considered.
Elderly Patients
No dose adjustment is required in elderly patients based on age alone. However, elderly patients are more likely to have reduced kidney and liver function, as well as concomitant diseases and medications. Therefore, clinical monitoring may be more frequent, and your doctor will consider the overall clinical picture when prescribing Rukobia in older adults. The BRIGHTE study included patients up to 72 years of age, and no significant age-related differences in safety or efficacy were observed.
Missed Dose
If you miss a dose of Rukobia, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and return to your regular dosing schedule. Do not take a double dose to make up for a forgotten dose. Consistent adherence is important for maintaining effective HIV suppression, so try to take your doses at regular intervals, approximately 12 hours apart. Setting reminders or alarms can help with adherence.
Overdose
If you have taken too many Rukobia tablets, contact your doctor or pharmacist immediately. If possible, show them the Rukobia packaging so they can identify the medication and dosage. There is no specific antidote for fostemsavir overdose. Treatment is supportive and symptomatic. In clinical studies, single doses up to 1200 mg have been administered without unexpected adverse effects, but exceeding the prescribed dose is never recommended.
Do not stop taking Rukobia without talking to your doctor first. Take Rukobia for as long as your doctor recommends to keep the HIV infection under control and prevent the disease from getting worse. If you stop treatment, HIV can resume replication, viral load will increase, and the virus may develop additional resistance mutations, further limiting your future treatment options.
What Are the Side Effects of Rukobia?
Like all medicines, Rukobia can cause side effects, although not everyone experiences them. The most common side effects include gastrointestinal symptoms (nausea, diarrhea, vomiting, abdominal pain), headache, and rash. Some side effects may only be detected through blood tests.
It is important to discuss any changes in your health with your doctor while taking Rukobia. Side effects can vary in severity from mild and transient to more significant effects requiring medical attention. Below is a comprehensive overview of reported side effects, organized by frequency.
Very Common
- Nausea
- Diarrhea
- Vomiting
- Abdominal pain (stomach pain)
- Headache
- Rash
Common
- Dyspepsia (indigestion)
- Fatigue (lack of energy)
- QT prolongation on ECG (heart rhythm disturbance)
- Myalgia (muscle pain)
- Somnolence (drowsiness)
- Dizziness
- Dysgeusia (altered taste)
- Flatulence (gas)
- Insomnia (difficulty sleeping)
- Pruritus (itching)
Blood Test Abnormalities (Common)
- Elevated creatine phosphokinase (CPK) — a marker of muscle damage
- Elevated creatinine — an indicator of kidney function
- Elevated transaminases (ALT/AST) — markers of liver function
- Elevated bilirubin — a substance produced by the liver
Immune Reconstitution Inflammatory Syndrome (IRIS)
- Unmasking of previously hidden infections as the immune system recovers
- Symptoms of autoimmune disorders (may appear months after starting treatment)
- Muscle weakness and pain
- Joint pain or swelling
- Weakness starting in hands/feet and moving toward the trunk
- Palpitations, tremor, or hyperactivity
Osteonecrosis (Bone Death)
Some people taking combination HIV therapy may develop a condition called osteonecrosis, where parts of the bone tissue die due to reduced blood supply to the bone. The risk may be higher in people who have been on combination treatment for a long time, who also take corticosteroids, who drink alcohol, who have a very weak immune system, or who are overweight.
Signs of osteonecrosis include stiffness in joints, aches and pain (particularly in the hips, knees, or shoulders), and difficulty moving. If you experience any of these symptoms, tell your doctor promptly so that appropriate evaluation can be undertaken.
It is important to report suspected side effects after a medicine has been approved. This makes it possible to continuously monitor the benefit-risk balance of the medicine. Healthcare professionals and patients are encouraged to report any suspected adverse reactions to their national pharmacovigilance authority (e.g., FDA MedWatch in the US, Yellow Card Scheme in the UK, or EMA EudraVigilance in Europe).
How Should You Store Rukobia?
Store Rukobia at room temperature, out of the sight and reach of children. No special storage conditions are required. Do not use after the expiry date printed on the packaging.
Rukobia does not require any special storage conditions. Keep the tablets in their original container with the lid tightly closed to protect them from moisture. Store the medicine at room temperature (typically 15–30°C / 59–86°F), away from direct sunlight and excessive heat.
Keep Rukobia out of the sight and reach of children. Do not use this medicine after the expiry date (EXP) stated on the carton and bottle. The expiry date refers to the last day of that month. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment.
What Does Rukobia Contain?
Each Rukobia 600 mg extended-release tablet contains fostemsavir tromethamine equivalent to 600 mg of fostemsavir, along with several inactive ingredients that form the extended-release matrix.
Active Ingredient
The active substance is fostemsavir. Each tablet contains fostemsavir tromethamine, equivalent to 600 mg of fostemsavir. Fostemsavir is a prodrug that is hydrolyzed to its active moiety, temsavir, which is responsible for the antiviral activity against HIV-1.
Inactive Ingredients (Excipients)
The other ingredients in Rukobia 600 mg extended-release tablets are:
- Tablet core: Hydroxypropylcellulose, hypromellose, colloidal anhydrous silica, magnesium stearate
- Film coating: Poly(vinyl alcohol), titanium dioxide (E171), macrogol 3350, talc, yellow iron oxide, red iron oxide (E172)
Appearance
Rukobia 600 mg extended-release tablets are beige, oval, biconvex tablets, approximately 19 mm long, 10 mm wide, and 8 mm thick. Each tablet is debossed with the code “SV 1V7” on one side. The tablets are packaged in bottles containing 60 extended-release tablets each. Packs may contain one or three bottles. Not all pack sizes may be marketed in every country.
Frequently Asked Questions About Rukobia
Rukobia (fostemsavir) is used in combination with other antiretroviral medicines to treat HIV-1 infection in adults who have limited treatment options because other antiretroviral medicines are not sufficiently effective or are not suitable. It is specifically designed for heavily treatment-experienced patients with multidrug-resistant HIV-1 who need a drug with a novel mechanism of action to build an effective regimen.
Rukobia is the first and only attachment inhibitor approved for HIV treatment. While most other HIV medicines work inside the cell after the virus has already entered, Rukobia blocks the virus at the earliest stage — before it can attach to and enter CD4+ T cells. It does this by binding to the gp120 protein on the surface of HIV-1, preventing the virus from interacting with the CD4 receptor. This novel target means Rukobia can work against HIV strains resistant to other drug classes.
Yes, Rukobia can be taken with or without food. There is no requirement to take it at mealtimes. However, it is important to take it at approximately the same times each day (about 12 hours apart) to maintain consistent drug levels in your body. The tablets must be swallowed whole with liquid and should not be chewed, crushed, or split.
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose. If you frequently miss doses, speak with your doctor about strategies to improve adherence, as consistent dosing is important for preventing HIV resistance.
Rukobia can be used in people with hepatitis B or C, but additional monitoring of liver function is recommended. Tell your doctor if you have liver disease before starting Rukobia. Note that elbasvir/grazoprevir (a hepatitis C treatment) is not recommended with Rukobia due to drug interactions. Your doctor will select an appropriate hepatitis C treatment regimen if needed.
No, Rukobia does not cure HIV infection. It helps control the virus by preventing it from entering and infecting new cells. When taken consistently as part of combination therapy, Rukobia reduces the viral load to undetectable levels in many patients and allows the immune system to recover. You must continue taking Rukobia every day as prescribed. If you stop, the virus can begin replicating again, potentially developing additional resistance.
References
- European Medicines Agency (EMA). Rukobia (fostemsavir) — Summary of Product Characteristics. Last updated 2025. Available at: EMA EPAR: Rukobia.
- U.S. Food and Drug Administration (FDA). Rukobia (fostemsavir) Prescribing Information. Approved July 2020. Available at: FDA Label.
- Kozal M, Aberg J, Pialoux G, et al. Fostemsavir in Adults with Multidrug-Resistant HIV-1 Infection. N Engl J Med. 2020;382(13):1232-1243. doi:10.1056/NEJMoa1902493.
- Lataillade M, Lalezari JP, Kozal M, et al. Safety and efficacy of the HIV-1 attachment inhibitor prodrug fostemsavir in heavily treatment-experienced individuals: week 96 results of the phase 3 BRIGHTE study. Lancet HIV. 2020;7(11):e740-e751.
- World Health Organization (WHO). Consolidated Guidelines on HIV Prevention, Testing, Treatment, Service Delivery and Monitoring. Geneva: WHO; 2021.
- Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents with HIV. Department of Health and Human Services (DHHS). Updated 2024.
- British HIV Association (BHIVA). Guidelines for the Treatment of HIV-1-positive Adults with Antiretroviral Therapy. 2024 update.
- European AIDS Clinical Society (EACS). Guidelines for the Clinical Management and Treatment of HIV-infected Adults in Europe. Version 12.0, 2023.
About the Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, consisting of licensed physicians specializing in infectious diseases, clinical pharmacology, and HIV medicine. Our editorial process follows international medical guidelines and the GRADE evidence framework.
Specialist physicians in infectious diseases and clinical pharmacology with documented academic backgrounds and clinical experience in HIV care.
Independent review board of medical experts who verify accuracy, completeness, and adherence to international treatment guidelines (WHO, DHHS, BHIVA, EACS).
All content is independent, free from pharmaceutical company sponsorship, and regularly updated to reflect the latest evidence-based guidelines.