Fuzeon

Entry Inhibitor

Common Name: enfuvirtide (ENF) or T-20

Brand Name: Fuzeon

Class: fusion inhibitor (a type of entry inhibitor)

Standard dose: One subcutaneous (under the skin) injection of 90 mg (1 ml) twice daily (every 12 hours) into the upper arm, thigh or abdomen. No food restrictions (take with or without food). Take missed dose as soon as possible, but do not double up on your next dose.

AWP: $2,841.20 / month for 90 mg kit

Manufacturer contact: Roche Pharmaceuticals and Trimeris, www.rocheusa.com, www.trimeris.com,
www.fuzeon.com, 1 (877) 4-FUZEON (438-9366)

AIDSInfo:
1 (800) HIV-0440 (448-0440), www.aidsinfo.nih.gov

Potential side effects and toxicity: The most common are Injection Site Reactions (ISRs), which occur in virtually all patients. The severity of reactions is variable, and for most is mild to moderate. Symptoms could include itching, swelling, redness, pain or tenderness, hardened skin or bumps. Bumps termed "nodules" seem to occur more frequently and severely in areas of high muscle mass (most notably the center of the stomach -- the abs -- and the legs). They will hurt with movement. Other side effects may include headache and fever. Allergic reactions are possible. In studies, pneumonia happened more often in the patients on Fuzeon. It is unclear if this was related to the use of Fuzeon, so report cough, fever, or trouble breathing to your health care provider immediately. Immune Reconstitution Inflammatory Syndrome (IRIS) may occur as the immune system regains strength; report symptoms of illness, such as shingles and TB, to health care provider.

Potential drug interactions: To date none found clinically significant.

Tips: With other powerful new drugs on the market, the twice-daily injectable Fuzeon has truly become a medicine of last resort. In fact, some specialists have been taking patients off Fuzeon and putting them on one of those newer drugs, Isentress. Several studies have shown good results with this strategy. Fuzeon is intended for treatment of HIV in patients who are treatment experienced. Preparing and injecting the Fuzeon can be complicated, so ask your health care provider how to do it. First, the drug needs to be dissolved with sterile water (provided in the kit), which may take 30 to 45 minutes. Never shake the vial with the Fuzeon, it will foam. Instead, roll it gently in your hands. You can store your second dose in the refrigerator, but it must be used within 24 hours (allow it to warm to room temperature before using). Before injecting, it is important to make sure that the Fuzeon powder is completely dissolved. To minimize injection site reactions, inject where you can pinch an inch (upper arm, stomach, or thigh). If not, then be sure to use half the length of the needle. Inject slowly and apply a gentle massage after injection. Try using vibrating devices after injections. Follow instructions to avoid infection. ISR may worsen when injection is repeated in the same spot or given deeper than intended, for example, into the muscle. Fuzeon can be taken at the same time as other anti-HIV drugs. Always rotate injection sites frequently. Never inject into moles, scars, bruises, nodules, or the navel. Switching to smaller needles, like insulin syringes, may also help with ISRs.

Fuzeon is the first and only anti-HIV compound on the market called a fusion inhibitor. Fusion inhibitors block fusion of HIV with a cell before the virus enters the cell and begins its replication process. Fusion inhibitors are a type of entry inhibitor, another one of which is in the pharmacy (Selzentry, taken orally). Because of injections, this drug will most likely be used in the heavily-treatment experienced and salvage therapy options. Two large Phase 3 studies showed good viral load decrease when added to an optimized antiviral combination in heavily treatment-experienced people, including those with protease inhibitor-resistant virus and those who've taken three drug classes. (Since those studies, however, there are now more drugs on the market, including another drug class.) Participants used three to five antivirals in addition to Fuzeon, and both genotype and phenotype tests.

U.S. HIV treatment guidelines support the use of Fuzeon with an active boosted protease inhibitor in patients who are heavily treatment-experienced. The guidelines supported the approach as it resulted in better and more prolonged virologic suppression than other regimens. Evidence included several studies of new boosted protease inhibitors in treatment-experienced patients which found an enhanced virologic response when used in conjunction with Fuzeon. This reinforces the principle of using two or more active drugs, if possible, when changing therapy, to make it more effective. Please see package insert for more complete potential side effects and interactions.

Doctor

Fuzeon (enfuvirtide, known to most as T-20) was approved (injection twice daily) for use in combination with other antiretroviral drugs in the treatment of HIV infection in 2003. Fuzeon is the first drug approved in the class of antiretrovirals called "entry inhibitors." Since this class of drug stops the virus from entering the CD4 cell, they are potentially a significant step forward for HIV therapy. The drawbacks to this drug are its high cost, need for injection, and injection site reactions. Injection site reactions (especially since injections are done twice daily) are a major issue with Fuzeon. If you have ever seen or are an individual who has injected T-20 -- you know. The "lumps" can be horrible and the skin leathery. In general, viral control with this drug has been good and at times even when viral control wasn't the best, the patient clinically felt well. Approval of other newer, more tolerable antiretrovirals has made Fuzeon an antiretroviral saved for deep salvage when an active drug is required. -- Frank M. Graziano, M.D., Ph.D.

Activist

Not for the faint of heart or those squeamish over needles, and definitely no fun. Fuzeon is a twice-daily injectable drug that must go through a fairly complicated "mixing" process (reconstitution) just to get it in the needle. Then, one has to contend with rather painful injection site reactions -- and it's woefully expensive. Fuzeon has the dubious reputation of being a measure of last resort, a salvage drug for the heavily treatment-experienced, but seems to increase CD4s and reduce viral loads when added to a multiple-drug regimen. If nothing else, Fuzeon can be an excellent motivator for adherence to more user-friendly treatment. -- Morris Jackson

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