Abbott Agrees To Cut Kaletra Drug Price For ADAPs – Abbott Laboratories announced last week that it has agreed to cut the price of its protease inhibitor Kaletra (lopinavir/ritonavir) for government-funded AIDS Drug Assistance Programs (ADAPs). Abbott will reduce the price of Kaletra by 8 percent to $5,037 per patient per year. ADAPs provide antiretroviral drugs to low-income people with HIV who cannot afford their medications. Due to the recession, many state ADAPs have been faced with budget cutbacks and increasing enrollment. According to the National Alliance of State and Territorial AIDS Directors, as of April 22, there were 7,674 people on ADAP waiting lists nationwide. For more information, please see the article in the Chicago Tribune.

Federal Judge Orders New York City To Restore AIDS Funding – A federal judge has ruled against a plan by New York City to cut funding for the city’s HIV/AIDS Service Administration (HASA). The proposed cuts would have eliminated 254 case managers from HASA’s staff. The judge ruled that the cuts violated New York City Local Law 49 and a federal court order that require HASA to maintain a case manager to client ratio of 1 to 34. The judge informed lawyers representing the city that they have 30 days to show that the budget cuts to HASA will not occur. For more information, please see the Housing Works press release.

Tobira Therapeutics Recruits Participants For Phase 2 Clinical Trial For CCR5 Inhibitor Cenicriviroc – Pharmaceutical company Tobira Therapeutics is currently recruiting participants to study the effectiveness, safety, and tolerability of its investigational CCR5 inhibitor cenicriviroc (TBR-652). Currently the only CCR5 inhibitor approved by the U.S. Food and Drug Administration is Selzentry (maraviroc). Participants will receive cenicriviroc plus Truvada (tenofovir/emtricitabine) or Sustiva (efavirenz) plus Truvada. The study is recruiting approximately 150 previously untreated HIV-positive adults. Trial locations include sites in Arizona, Florida, New York, and New Jersey. For more information, please see the U.S. Clinical Trials Registry.

Florida ADAP Running Out Of Money For Anti-HIV Drugs – Florida’s AIDS Drug Assistance Program (ADAP) has run out of money and will need an additional $14.5 million before April if it is to continue running, according to state officials. Without additional funds Florida’s ADAP will have to stop providing anti-HIV drugs by next month. Florida has already instituted a waiting list for the program; at 2,500 people, Florida’s waitlist is larger than any other state’s. Officials have said unprecedented demand from people who have lost their jobs or insurance has strained the program’s finances. ADAP managers are looking to other government programs and assistance from pharmaceutical companies, charities, and other possible funding sources. For more information, please see the Highlands Today website.

French Doctor Calls For Creation Of International Coalition To Find A Cure For HIV – Dr. Alain Lafeuillade, chief of the department of infectious diseases at General Hospital in Toulon, France, has issued a call for the creation of an international agency dedicated to finding a cure for HIV. Dr. Lafeuillade states that costs for universal treatment of HIV are unreasonable and that government and private investors should focus instead on trying to cure HIV by eliminating latent HIV reservoirs – HIV that lies dormant and can start multiplying again if antiretroviral therapy is stopped. Current antiretrovirals cannot get rid of latent HIV. Dr. Lafeuillade argues that scientific breakthroughs have made such a cure feasible but need to be further pursued by creating an international agency dedicated to research on the topic. For more information, please see the press release by Dr. Lafeuillade.

However, one study that examined the efficacy of single versus double boosted protease inhibitors in adults with drug-resistant HIV found that double boosted protease inhibitors offered no additional benefits over single boosted.

Although antiretroviral therapy is usually highly successful at treating HIV, drug-resistant forms of the virus have emerged over time. Studies have suggested that about 15 percent of HIV strains show resistance to treatment with traditional antiretroviral drugs.

In some cases people have HIV that is resistant to all three of the main antiretroviral drug classes – nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors.

Newer Antiretroviral Drugs Are Effective For Treating Drug-Resistant HIV

A team of researchers in Spain found that four newer antiretroviral drugs – Isentress (raltegravir), Selzentry (maraviroc), Prezista (darunavir), and Intelence (etravirine) – safely and effectively treated people with drug-resistant HIV.

The small study examined people the researchers called “hard rescues” – patients with virologic failure, or a viral load (amount of virus in the blood) measuring greater than 50 copies per milliliter in two consecutive measurements, whose HIV was resistant to all three main antiretroviral classes.

Most of the patients (84 percent) were assigned to more than one of the new drugs, with 56 percent receiving more than two. In total, 84 percent received Isentress, 80 percent Prezista, 52 percent Selzentry, and 24 percent Intelence.

After 24 months, 78 percent of the study participants had undetectable viral loads, with a median CD4 (white blood cell) count of 634 cells per microliter.

There were no deaths during the study period, and none of the participants were hospitalized for opportunistic infections (infections that do not occur in individuals with healthy immune systems).

The researchers concluded that newer antiretrovirals are safe and effective for treatment of people with drug-resistant HIV.

Isentress Is Effective At Reducing Viral Loads In People With Highly Drug-Resistant HIV

A small study by the British Columbia Centre for Excellence in HIV/AIDS in Canada found that Isentress was capable of achieving viral suppression in up to 81 percent of highly drug-resistant HIV-positive patients.

Isentress is an integrase inhibitor, a relatively new class of antiretroviral drugs that work differently than most antiretrovirals. As a result, it can be effective against HIV strains that are resistant to more common antiretrovirals.

The study followed 112 individuals who were already treatment-experienced, with a median of 8 treatment switches before beginning treatment with Isentress.

At the end of the study, 81 percent of participants had achieved viral suppression – a viral load of 50 copies per milliliter or less – and participant CD4 cell counts increased a median of 15 percent over 17 months.

The researchers concluded that new antiretroviral drugs such as Isentress allow even patients with highly drug resistant HIV to successfully reach viral suppression.

Selzentry Is Safe And Effective In Treatment-Experienced Patients With Drug-Resistant HIV

Researchers in Italy conducted a small study to assess the effectiveness and safety of Selzentry in treatment-experienced patients with multi-drug-resistant HIV.

Selzentry is an entry inhibitor, a relatively new class of antiretrovirals that work by preventing HIV from entering human cells. Since it works differently than most antiretrovirals, it can be effective even against strains of HIV that are resistant to most antiretroviral drugs.

The study included 33 treatment-experienced patients with multi-drug-resistant HIV. After two months of treatment with Selzentry plus other antiretrovirals, 82 percent of study participants achieved viral suppression.

Participants also experienced notable increases in CD4 cell count, with a median increase of 10 cells per month.

Selzentry was used in combination with several different types of antiretrovirals, including boosted protease inhibitors such as Prezista; NNRTIs such as Intelence; and the integrase inhibitor Isentress. One study participant took Selzentry with Fuzeon (enfuvirtide).

In all cases and combinations, researchers concluded that Selzentry was both well-tolerated and effective in treating HIV-positive adults with multi-drug-resistant HIV.

CD4 Cell Counts Increase Faster During Treatment With Fuzeon

A small French study found that patients with drug-resistant HIV experienced greater CD4 cell count increases when Fuzeon was added to their optimized antiretroviral drug regimens.

Fuzeon is an entry inhibitor. Like Selzentry, it works by preventing HIV from entering and infecting human immune system cells.

During the study, half of the participants received a short, three-month course of Fuzeon in addition to an optimized antiretroviral drug regimen; the other half received the optimized regimen without Fuzeon.

After three months, participants who received Fuzeon had median CD4 cell counts that were 110 cells per microliter higher than participants who did not take Fuzeon.

Three months after the first group stopped taking Fuzeon, however, the two groups had the same median CD4 cell counts of 520 cells per microliter, suggesting that the immune system benefits of Fuzeon did not last once participants stopped taking it.

The two groups were equally successful at achieving viral suppression, indicating that adding Fuzeon did not provide additional improved viral control.

The researchers concluded that Fuzeon may have a beneficial effect on immune system restoration and that this effect is independent of its antiviral activity.

No Advantage Found In Treatment With Double Boosted Versus Single Boosted Protease Inhibitors

In a comparison between single boosted and double boosted protease inhibitor treatments, double boosted protease inhibitors were found to have no additional benefit over single boosted in people with HIV who were resistant to NNRTIs.

Boosting protease inhibitors is a method of increasing their effectiveness by administering Norvir (ritonavir) simultaneously. Norvir slows down the rate at which other protease inhibitors are broken down in the body, which keeps their concentrations in the blood higher.

The study was conducted by researchers at a hospital in Thailand and included 64 participants, none of whom had taken protease inhibitors before. All of the participants had previously exhibited resistance to treatment with NNRTIs.

Forty of the participants were given a single boosted protease inhibitor regimen of Kaletra (lopinavir/ritonavir), which contains Norvir. The rest received a double boosted regimen containing Reyataz (atazanavir), Invirase (saquinavir mesylate), and Norvir.

After 48 weeks, no difference was observed between the two treatment strategies in terms of effectiveness and side effects.

By the end of the study, 60 percent of participants taking the single boosted protease inhibitor achieved viral suppression versus 67 percent in the double boosted group. There were no differences in final CD4 counts or side effects such as raised cholesterol levels.

The researchers concluded that there was no added benefit to using a double boosted versus single boosted protease inhibitor regimen.

For more information, please see the AIDS 2010 conference website.

The guidelines include updates on preferred regimens for prevention of HIV transmission during pregnancy.

According to the report, fewer than 200 children are now born with HIV in the United States each year, as a result of efforts to limit mother-to-child transmission.

Transmission of HIV from a pregnant woman to her baby can occur during pregnancy, labor, or while breastfeeding after the baby is born. To prevent this, women are usually treated with antiretrovirals throughout the pregnancy and are told not to breastfeed their babies.

In this latest report, the NIH now recommends that pregnant women with HIV who are not already taking antiretrovirals start taking them sooner than previously suggested. The NIH suggests initiating treatment after the first trimester, and no later than 28 weeks into the pregnancy.

The guidelines also recommend pregnant women take a combination regimen consisting of at least three drugs, preferably two nucleoside reverse transcriptase inhibitors (NRTIs) and one non-nucleoside reverse transcriptase inhibitor (NNRTI) or protease inhibitor.

The recommended NRTI regimen is Combivir (zidovudine/lamivudine), based on clinical trials demonstrating its effectiveness.

The recommended NNRTI is Viramune (nevirapine), although only in women with CD4 cell counts of less than 250 cells/mm3 unless the benefits outweigh the risk of potential liver toxicity. Women already taking Viramune may continue during pregnancy.

The recommended protease inhibitor regimen is Kaletra (lopinavir/ritonavir). Alternative protease inhibitors include Norvir (ritonavir) in combination with Invirase (saquinavir), Crixivan (indinavir) or Reyataz (atazanavir).

Several treatments are not recommended for part or all of the pregnancy:

• The combination of stavudine (Zerit) and didanosine (Videx) are not recommended since they may cause serious side effects, including liver failure, in pregnant women.

• Sustiva (efavirenz) should not be taken in the first trimester of pregnancy because of possible harm to the baby. Sustiva is also an ingredient in Atripla (efavirenz/emtricitabine/tenofovir).

• Viread (tenofovir) should only be used when there is intolerance or resistance to zidovudine (Retrovir) or if the pregnant woman has hepatitis B because it may harm the baby. Viread is also an ingredient in Atripla and Truvada (emtricitabine/tenofovir).

• There is not yet enough data on Intelence (etravirine), Prezista (darunavir), Lexiva (fosamprenavir), Aptivus (tipranavir), Fuzeon (enfuvirtide), Selzentry (maraviroc), or Isentress (raltegravir) to recommend their use in pregnancy, although in some cases they may be used if other drugs are not well tolerated.

Prevention of mother-to-child transmission in HIV-positive women with hepatitis B (HBV) is also discussed. Treatment options depend on whether the mother requires anti-HIV treatment for her own health, anti-HBV treatment, or both.

The NIH also reaffirmed its recommendation that HIV-positive women should avoid breastfeeding. Although clinical trials in Africa have shown that antiretrovirals reduce the chances of transmitting HIV through breastfeeding, there is still a risk.

Since women in the U.S. have a safe, viable alternative to breastfeeding – formula feeding – the NIH strongly discourages HIV-positive women from breastfeeding.

After the baby is born, antiretroviral treatment of the infant is usually continued to ensure infection does not occur. The recommended treatment is zidovudine for six weeks after birth. In the new guidelines, the NIH warns that combining zidovudine with other treatments is not well-studied and should be done with caution.

Both Norvir and Kaletra have been associated with heart block, a problem with the heart’s electrical system, in babies, and therefore require especially close monitoring if used in infants.

Finally, food pre-chewed by HIV-positive caregivers should not be given to infants since this potentially increases the risk of HIV transmission.

The NIH welcomes feedback on the guideline revisions. Comments should be sent to ContactUs@aidsinfo.nih.gov with the subject line “Perinatal Comments” by June 7, 2010.

For more information, please see the complete guidelines at the NIH (pdf) website.

Description

Fuzeon is the first fusion inhibitor approved by the U.S. Food and Drug Administration for patients who have already started antiretroviral therapy for HIV infection. Fusion inhibitors are drugs that disable HIV from “fusing,” or binding, to healthy CD4 cells in HIV-positive patients. Fuzeon must be used in combination with other drugs – usually three or four – in a regimen known as Highly Active Antiretroviral Treatment (HAART).

Fuzeon is an option for patients who don’t respond well to other HIV treatments or have developed resistance to other HIV drugs. The FDA has not approved Fuzeon for HIV-positive patients beginning drug therapy for the first time. Fuzeon is only approved to treat adults or children ages 6 years or older for HIV-1.

Mechanism of Action

Fuzeon prevents HIV from infecting healthy CD4 cells by binding to the virus’s “gp41” protein on the surface of the virus. This prevents HIV copies from attaching to the surface of CD4 cells. Currently, Fuzeon is the only FDA approved fusion inhibitor in the Entry Inhibitor drug class. The drug is unique for its ability to target the virus’s protein to prevent membrane fusion (binding and fusing) rather than proteins on the surface of the human cell.

By disabling HIV infections in CD4 cells, Fuzeon may improve CD4 count because healthy cells are able to divide into new, uninfected daughter cells. This also results in a decrease of viral load.

History

The active ingredient in Fuzeon, enfuvirtide (T-20), was created by the pharmaceutical company Trimeris in 1996. Three years later, Trimeris partnered with Hoffmann-La Roche Inc. to develop the drug further. Fuzeon was approved by the FDA on March 15, 2003 as a treatment component for HIV-1 in patients who have already undergone antiretroviral therapy.

Usage in HIV

Fuzeon is often an option for patients unresponsive to previous antiretroviral treatments. For the best results, researchers suggest taking Fuzeon with other HIV drugs that are still fully or moderately effective in treating HIV if a patient has developed resistance to other antiretroviral drugs. Although Fuzeon is an alternative to drugs an individual has developed resistance to, it should be taken with other medications with little resistance to achieve the best possible outcome.

Dosage and Administration

Fuzeon cannot be taken in pill form because it has a fragile structure. Instead, the drug must be injected under the skin twice daily. Ninety milligrams (mg) of Fuzeon is considered one dose – making daily intake of the drug 180 mg for individuals receiving the treatment. The drug can be injected into areas near the lower stomach, upper arm, or upper leg. To prevent infection or irritation, individuals should avoid using the same injection sites more than once in a day or two.

The drug is originally packaged as two separate vials: one with the drug in powder form, and another with sterilized water to mix with the powder. Both vials must be stored at room temperature (59 to 86 degrees Fahrenheit) or in a refrigerator if room temperature storage is not an option. To prepare a dose, the contents of the water vial must be transferred and mixed with the powder in the opposite vial with a sterile syringe. For best results, the powder must be completely dissolved in the liquid.

If a dose is mixed, it must either be used immediately or stored for use up to 24 hours in the refrigerator. Food does not affect Fuzeon, so patients can take the drug on an empty or full stomach.

Taking Fuzeon regularly is important for the health of the patient using the drug. If doses are missed or skipped, patients are at an increased risk of HIV developing resistance to Fuzeon, making the virus harder to treat. If a patient misses a dose, he or she should prepare and inject the dose as soon as possible. If the missed dose is close to the next planned one, do not take two doses. Instead, wait 12 hours to administer more of the drug.

Like all other injectable medications, patients should carefully handle and dispose used syringes in specialized containers for sharp objects. Syringes should never be thrown in the trash can. Patients should talk to their doctor or pharmacist about obtaining a specialized container and how to dispose of used syringes.

For children ages 6 to 16 years, dosage is calculated by weight. For every kilogram of a child’s weight, two milligrams of Fuzeon are measured and administered. Children should still take two doses per day without exceeding 90 milligrams of the drug.

Since Fuzeon can be difficult to prepare and administer, Roche offers a free support program for patients taking or starting the drug. The Nurse Connections Program is dedicated to helping patients prepare Fuzeon vials for use. The program connects patients to nurses who visit patients at home and teach them how to inject properly. In addition, the program has an assistance hotline staffed by nurses to answer any questions patients have about the drug, including how to prepare and administer Fuzeon.

Side Effects

Irritation and inflammation of injection sites are common side effects from using Fuzeon. Pain, discomfort, hardened skin, redness, bumps, itching, and swelling may occur. Contact a physician immediately if a severe skin reaction develops or if these symptoms last more than seven days.

Results from a clinical trial by Hoffmann-La Roche recorded two cases of bacterial pneumonia thought to result from the use of Fuzeon. One patient with the condition discontinued treatment and subsequently died. Bacterial pneumonia did not occur in the other control groups of the study who were taking other HIV medications, but not Fuzeon. At this time, researchers do not know the relationship between Fuzeon and bacterial pneumonia. Notify a physician immediately if a cough, fever, or issues with breathing arise.

More common side-effects include peripheral neuropathy (damage to nerves in the brain and spinal cord), insomnia, depression, decreased appetite, fatigue, muscle pain, constipation, sinus problems, enlarged lymph nodes, loss of weight, weakness or loss of strength, pancreas problems, and glomerulonephritis – inflammation of the glomeruli (small blood vessels in the kidneys).

In rare cases, some patients have allergic reactions to the drug. Symptoms of an allergic reaction to Fuzeon include rash, trouble breathing, fever with vomiting, nausea, blood in the urine, swelling of the feet, chills, shaking, low blood pressure, and increased liver enzymes.

Drug Interactions

Fuzeon is not known to interact with the effectiveness of other medications, including other HIV drugs, but the drug can negatively affect some medical conditions. Patients who are allergic to any of Fuzeon’s ingredients should not consider taking it. Because each person has a different reaction or sensitivity to drugs, patients should discuss all medical conditions and both over-the-counter and prescription medications while taking Fuzeon. Similarly, patients taking the drug should talk to a physician about alcohol consumption and if adverse reactions occur.

Precautions

Women who are pregnant or breastfeeding should talk to a doctor about taking Fuzeon. The FDA lists Fuzeon as a “Category B” threat, which means that animal trials have shown that Fuzeon was no risk to fetuses; however, there have been no such controlled studies on pregnant woman. Although it is not clear whether Fuzeon can be transferred through breast milk, HIV-positive women should not breastfeed because of the possibility of the virus being transferred to the child.

Patients should discuss their medical conditions with their doctors before and while using the drug. Although Fuzeon increases CD4 counts and decreases viral loads, patients can still experience opportunistic infections. Fuzeon does not slow the transmission of HIV, so patients must continue to use condoms or other forms of protection to prevent transmission of the virus during sexual intercourse.

Ongoing Clinical Trials:

Open:

Currently, there are four open clinical trials for Fuzeon, most for the development of new combination therapies.

Phase not determined (0):

• National Institute of Allergy and Infectious Diseases (NIAID): Safety and effectiveness of addition of maraviroc to ART regimens in HIV-infected adults with suboptimal CD4 T-cell count recovery despite sustained virologic suppression (NCT00709111)

Phase 2:

• Canadian Immunodeficiency Research Collaborative: Study to assess safety and quality of life of patients using biojector versus needles for Fuzeon administration (NCT00333736)

Phase 2/3:

• University of California, San Diego: Clinical trial of CNS-targeted HAART (CIT2) (NCT00624195)

Phase 3:

• National Institute of Allergy and Infectious Diseases (NIAID): Optimizing treatment for treatment-experienced, HIV infected people (NCT00537394)

Closed:

Phase not determined:

• Institute for Interdisciplinary Infectiology: Cohort study for patients using Fuzeon (NCT00216359)

• National Institute of Allergy and Infectious Diseases (NIAID): Effect of a Fuzeon-based anti-HIV drug regimen on latent HIV reservoirs in treatment naive adults (NCT00051831)

• National Institute of Allergy and Infectious Diseases (NIAID): Treatment Intensification for HIV Infected Patients With Multi-Drug Resistant Virus (NCT00102934)

Phase 2:

• Hoffmann-La Roche: INNOVE Study: A study of 3 months induction with Fuzeon + Optimized Background (OB) versus OB alone in HIV-1 infected patients with virological failure (NCT00615134)

Phase 3:

• French National Agency for Research on AIDS and Viral Hepatitis: Intensification with Fuzeon in naive HIV-infected patients (ANRS130) (NCT00302822)

For a more detailed listing of clinical trials involving Fuzeon, please see the U.S. government clinical trials Web site.

Clinical Trial Results:

A study to evaluate the safety and efficacy of adding Fuzeon to oral highly active antiretroviral therapy (HAART) in human immunodeficiency virus (HIV) patients with prior treatment experience (2008): The study compared patients taking Fuzeon with HAART to the results of patients taking HAART alone. Fuzeon used with HAART resulted in better viral suppression. A summary of the study can be found at the Clinical Trials Web site.

BLQ Study: A study of a protease inhibitor with Fuzeon in treatment-experienced patients with HIV-1 (2006): The experimental study measured the safety and effectiveness of Fuzeon with developing protease inhibitors. The study confirmed that Fuzeon is a safe and effective addition to protease inhibitor treatments. A summary of the study can be found at the Clinical Trials Web site.

Fuzeon, an HIV-1 fusion inhibitor, for drug-resistant HIV infection in North and South America (also known as the TORO 1 study group) (2003): Along with the TORO 2 study group, this Phase 3 study of Fuzeon was the basis for FDA approval of the drug in 2003. Researchers found that when the drug was used with other HIV medications, viral load decreased more and CD4 cells increased in comparison to treatments undergone over the course of at least six months by the same patients. Patients were twice as likely to achieve undetectable plasma levels of HIV in comparison to patients receiving an antiretroviral alone. These patients were previously treated with three classes of other antiretroviral drugs, with some patients having developed resistance to other HIV drugs. The study can be found in the New England Journal of Medicine.

Efficacy of Fuzeon in patients infected with drug-Resistant HIV-1 in Europe and Australia (also known as the TORO 2 study group) (2003): This Phase 3 study concluded that an optimized background regimen with Fuzeon was effective in combination with other HIV medications in decreasing viral load and increasing CD4 cell count.  The study can be found in the New England Journal of Medicine.

Patient Assistance Programs:

Roche Patient Assistance Foundation
877-757-6243
http://www.rocheusa.com/programs/patientassist.asp

Fuzeon Reimbursement Assistance Program
877-4FUZEON
http://www.fuzeon.com/consumer/reimbursement_assistance.aspx

Roche Nurse Connections Program
877-438-9366
http://www.fuzeon.com/consumer/fuzeon_nurse_connections.aspx

Links of Interest

Fuzeon Product Web site
http://www.fuzeon.com/

Disposing of used needles responsibly
http://www.rocheusa.com/sharps/index.asp

The FDA approves Fuzeon
http://www.fda.gov/ForConsumers/ByAudience/ForPatientAdvocates/HIVandAIDSActivities/ucm125088.htm

Roche’s Detailed Information on Fuzeon for Patients and Caregivers
http://www.rocheusa.com/products/fuzeon/ppi.pdf

Fuzeon is injected into the body, while Selzentry is taken orally. Both drugs work by preventing the virus from entering and infecting human immune cells. Fuzeon binds to an HIV protein and blocks its necessary conformational change to bring the viral and cellular membranes together. Selzentry prevents the virus from binding to a host cell protein that HIV uses as a co-receptor to preferentially infect macrophages. This binding is necessary to form a stable interaction between the two membranes.

In addition to providing drug-resistant HIV patients with a new treatment alternative, Fuzeon and Selzentry have been proven effective in clinical trials. Results published in July of 2007 showed 64 percent of participants taking Fuzeon achieved undetectable levels of HIV, which is less than 50 copies of the virus per mL of blood. Selzentry clinical trial results in February earlier that year showed significant increases in HIV suppression and CD4 T cell counts in comparison to control groups.

Drawbacks to fusion inhibitors include their administration, side effects, and restricted application. Fuzeon requires injection twice a day and causes injection site reactions. During clinical trials, participants taking Fuzeon had increased incidences of bacterial pneumonia. Selzentry is broken down by the liver and may cause complications with other medications. Its usage is limited by the type of HIV virus and will be much less effective against strains that use a different co-receptor. Additionally, both of these drugs are not recommended for people undergoing therapy for the first time.

Other experimental drugs are still awaiting FDA approval. Schering-Plough’s Vicriviroc, Progenics’s PRO140, and Tanox’s TNX-355 all inhibit different proteins involved in HIV attachment and fusion, which is necessary for the virus to infect healthy human cells and cause the disease.