Enfuvirtide

Enfuvirtide is a prescription drug used for the treatment of HIV, the virus that causes AIDS. It belongs to a family of antiretroviral drugs called fusion inhibitors. It was the first fusion inhibitor to be developed. Fusion inhibitors prevent the HIV viral particle from "fusing" with the host cell (see video). The Food and Drug Administration approved enfuvirtide on March 13, 2003. Enfuvirtide is sold under the name Fuzeon and is co-marketed by Roche and Trimeris. In the United States, enfuvirtide is very expensive (annual treatments can cost $25,000). This cost, coupled with injections that need to be administered twice daily, have relegated the use of enfuvirtide to use in combination with other drugs in people for whom previous treatments have failed.

Uses

Enfuvirtide is indicated for the treatment of HIV-1 infection in people for whom previous treatments are ineffective. It is used in combination with other HIV—1 drugs.

How Enfuvirtide is Taken

Enfuvirtide is supplied in a 90 mg/ml vial. The recommended dose is 90 mg (1 ml) twice daily injected subcutaneously (below the skin) into the upper arm, anterior thigh or abdomen. In children 6–16 years of age, the recommended dosage is 2 mg/kg twice daily up to a maximum dose of 90 mg twice daily.

How Enfuvirtide Works

Enfuvirtide is a fusion inhibitor, or entry inhibitor. Fusion inhibitors prevent the entry of HIV into cells by inhibiting the fusion of the virus to the host cell. Specifically, enfuvirtide binds to a protein on the surface of HIV-1 called gp41. This protein normally attaches to cell membranes and forms a pore through them. The pore allows the virus to enter the host cell. Enfuvirtide hinders attachment of the virus to the cell membrane, prevents pore formation and infection of the host cells.

How the Body Affects Enfuvirtide

Peak circulating levels of enfuvirtide are reached approximately eight hours post-dosing. Enfuvirtide is a protein and is broken down into its amino acid constituents just like proteins made in the body. The concentration of enfuvirtide in the blood is reduced by half in approximately 3.8 hours.

Side Effects

Below are the most common side effects of enfuvirtide:

• Injection site reactions
• Weight loss
• Sinusitis
• Abdominal Pain
• Cough
• Herpes Simplex infection
• Pancreatitis
• Pain in the limbs
• Pneumonia
• Muscle aches
• Flu-Like Illness
• Infection of the hair follicles
• Decreased or loss of appetite
• Dry Mouth
• Conjunctivitis (pink eye, inflammation of the thin membrane covering the cornea)
• Insomnia
• Depression
• Hypersensitivity or allergic reactions (fever, rash, nausea, vomiting, low blood pressure, chills)

Injection site reactions occur in almost all people taking enfuvirtide. Some of these reactions include redness or itching at the site of injection.

Risks and Precautions

Precaution is warranted in people who are susceptible to pneumonia. Some risk factors for the development of pneumonia during treatment with enfuvirtide include smoking, intravenous drug use, history of lung disease, and high viral load.

The effects of enfuvirtide on pregnancy are not known. Animal studies showed that enfuvirtide did not cause fetal harm.

Drug Interactions

Few drug interactions are likely with enfuvirtide because the drug is not metabolized in the liver. Accordingly, no significant interactions have been reported.

History

Enfuvirtide was developed by researchers at Duke University in the United States. The researchers formed the company Trimeris and originally investigated enfuvirtide as an HIV vaccine. Trimeris partnered with Roche in 1999 and completed development of the drug. The U.S. Food and Drug Administration approved enfuvirtide four years later.

Clinical trials

One study of over 500 patients showed that the addition of enfuvirtide to an ongoing medication regimen provided significant viral suppression and immunologic benefit in HIV-1–infected patients who had previously received multiple antiretroviral drugs.^[1]

References

1. ↑ Lazzarin A, Clotet B, Cooper D, et al. Efficacy of Enfuvirtide in Patients Infected with Drug-Resistant HIV-1 in Europe and Australia. N Engl J Med. 2003 May 29;348(22):2186-95. Abstract | Full Text | PDF

External Links

FDA: Patient Information Sheet

• Drugs.com