Research Triangle Park, NC - July 22, 2008 - The U.S. Food and Drug Administration (FDA) has approved GlaxoSmithKline's request to add new language to the prescribing information for its HIV nucleoside reverse transcriptase inhibitor (NRTI) Ziagen (abacavir sulfate). The newly added information recommends taking into consideration two separate factors in prescribing decisions: patients' HLA-B*5701 allele status and underlying heart disease risk factors when prescribing antiretroviral therapies including abacavir.

The FDA approved language regarding the association between abacavir hypersensitivity reaction (ABC HSR) and the HLA-B*5701 allele, a genetic marker. ABC HSR, which occurs in approximately eight percent [8%] of patients and usually emerges within the first six weeks of therapy, is a potentially serious and sometimes fatal allergic reaction that has been reported in certain patients taking abacavir.

Screening for the HLA-B*5701 allele is recommended for any patient prior to initiating HIV treatment with abacavir, or prior to reinitiation of it in patients who have previously tolerated abacavir but whose HLA-B*5701 status is unknown. Screening has been found to decrease the risk of ABC HSR by avoiding the use of abacavir in patients who are positive for the HLA-B*5701 allele. It is recommended that physicians do not initiate treatment with an abacavir-containing regimen in any patient that screens positive for the HLA-B*5701 allele.

This update to the Ziagen product labeling is based on PREDICT-1 (Prospective Randomised Evaluation of DNA screening In a Clinical Trial), a randomized, double-blind study published in the February 7, 2008 issue of the New England Journal of Medicine. PREDICT-1 demonstrated that the exclusion of patients who screened positive pre-therapy for HLA-B*5701 significantly reduced the incidence of clinically suspected ABC HSR from 7.8% to 3.4%.

"Screening for HLA-B*5701 has been shown to reduce the incidence of ABC HSR by allowing healthcare professionals to identify patients who may be at a higher risk of developing this adverse reaction," said John Pottage, MD, VP Global Clinical Development Antivirals, GSK.

In addition to the information on HLA-B*5701 screening, wording was also added to the Ziagen product label regarding the findings of a prospective, observational, epidemiological study, "The Data collection of Adverse effects on anti-HIV Drugs (D:A:D) Study." This study was published in the April 26, 2008 issue of The Lancet. Results of this study of over 30,000 patients suggest that current or recent use (within the past 6 months) of abacavir may be associated with a potential increased risk of myocardial infarction [heart attack].

Also included in the label is a pooled analysis of 54 GSK-sponsored clinical trials involving abacavir and found no relationship between use of abacavir and increased risk of myocardial infarction. This analysis included a total of almost 10,000 patients receiving abacavir. The labeling states that in totality, the available data from the observational cohort and clinical trials are inconclusive.

As a precaution, GSK requested a label update to inform health care providers that the underlying risk of coronary heart disease should be considered when prescribing antiretroviral therapies, including abacavir, and action should be taken to minimize all modifiable risk factors (e.g., hypertension, hyperlipidemia, diabetes mellitus, and smoking).

About Abacavir

Abacavir sulfate is a nucleoside reverse transcriptase inhibitor with a proven safety and efficacy profile as part of an HIV treatment regimen. Abacavir is a key component in Ziagen, Trizivir and Epzicom. The most significant treatment-limiting event known to occur with abacavir is a hypersensitivity reaction, which occurs in approximately eight percent of patients and emerges within the first six weeks of therapy.

Important Safety Information about ZIAGEN

Ziagen, in combination with other antiretroviral agents, is indicated for the treatment of HIV-1 infection in adults.

Ziagen is one of 3 medicines containing abacavir. Before starting Ziagen, your healthcare professional will review your medical history in order to avoid the use of abacavir if you have experienced an allergic reaction to abacavir in the past.

In one study, more patients had a severe hypersensitivity reaction in the abacavir once-daily group than in the abacavir twice-daily group.

Ziagen does not cure HIV infection/AIDS or prevent passing HIV to others.

Important Safety Information

Ziagen contains abacavir sulfate, which is also contained in Epzicom (abacavir sulfate and lamivudine) and Trizivir (abacavir sulfate, lamivudine, and zidovudine). Patients taking Ziagen may have a serious allergic reaction (hypersensitivity reaction) that can cause death.

If you get a symptom from 2 or more of the following groups while taking Ziagen, stop taking Ziagen and call your doctor right away:

1. Fever
2. Rash
3. Nausea, vomiting, diarrhea, or abdominal (stomach area) pain
4. Generally ill feeling, extreme tiredness, or achiness
5. Shortness of breath, cough, or sore throat.

Carefully read the Warning Card that your pharmacist gives you and carry it with you at all times.

If you stop Ziagen because of an allergic reaction, NEVER take Ziagen or any other abacavir-containing medicine (Epzicom, Trizivir) again. If you take Ziagen or any other abacavir-containing medicine again after you have had an allergic reaction, WITHIN HOURS you may get life-threatening symptoms that may include very low blood pressure or death.

If you stop Ziagen for any other reason, even for a few days, and you are not allergic to Ziagen, talk with your healthcare professional before taking it again. Taking Ziagen again can cause a serious or life-threatening reaction, even if you never had an allergic reaction before. If your healthcare professional tells you that you can take Ziagen again, start taking it when you are around medical help or people who can call a doctor if you need one.

A buildup of lactic acid in the blood and an enlarged liver, including fatal cases, have been reported.

Do not take Ziagen if your liver does not function normally.

Worsening of liver disease (sometimes resulting in death) has occurred in patients infected with both HIV and hepatitis C virus who are taking anti-HIV medicines and are also being treated for hepatitis C with interferon with or without ribavirin. If you are taking Ziagen as well as interferon with or without ribavirin and you experience side effects, be sure to tell your doctor.

When you start taking HIV medicines, your immune system may get stronger and could begin to fight infections that have been hidden in your body, such as pneumonia, herpes virus, or tuberculosis. If you have new symptoms after starting your HIV medicines, be sure to tell your doctor.

Changes in body fat may occur in some patients taking antiretroviral therapy. These changes may include an increased amount of fat in the upper back and neck ("buffalo hump"), breast, and around the trunk. Loss of fat from the legs, arms, and face may also occur. The cause and long-term health effects of these conditions are not known at this time.

Some HIV medicines including Ziagen may increase your risk of heart attack. If you have heart problems, smoke, or suffer from diseases that increase your risk of heart disease such as high blood pressure, high cholesterol, or diabetes, tell your doctor.

The most common side effects of Ziagen include nausea, vomiting, tiredness, headache, diarrhea, trouble sleeping, fever and chills, and loss of appetite. Most of these side effects did not cause people to stop taking Ziagen.

For additional important information about Ziagen please visit www.treathiv.com

About GlaxoSmithKline

GlaxoSmithKline is one of the world's leading research-based pharmaceutical and healthcare companies and an industry leader in HIV research and therapies. The company is engaged in basic research programs designed to investigate new targets to treat HIV. For full prescribing information please go to www.TreatHIV.com.