Study finds that co-administration of LEXIVA with esomeprazole does not affect blood levels of LEXIVA

Research Triangle Park, NC- July 5, 2006 – A study published in the Journal of Acquired Immune Deficiency Syndrome (JAIDS), demonstrated that the protease inhibitor LEXIVA® (fosamprenavir calcium) may be administered simultaneously with Nexium® (esomeprazole) without dose adjustment. The data showed that blood levels of LEXIVA remained unchanged when patients took LEXIVA 1400mg BID (twice-a-day) or LEXIVA 700 mg + ritonavir 100 mg bid at the same time as 20 mg once-daily esomeprazole.

“Drug interactions are an important consideration for all patients. Certain medications may be sensitive to the body’s normal environment. If taken with another medication that lowers levels of stomach acid, it might have an effect on the levels of the protease inhibitor in the blood,” said Mark Shaefer, Pharm. D., acting vice president, HIV, Infectious Disease Medicine Development Center at GlaxoSmithKline.

The authors point out that among HIV-positive patients, heartburn, gastroesophageal reflux disease and ulcers are common disorders. A survey of 200 HIV-positive patients found that nearly 80 percent of patients have used an OTC acid-reducing agent and 39 percent used a prescription proton pump inhibitor (PPI).1 In the month prior to the survey, 28 percent reported using an antacid, 25 percent used a prescription PPI and 13 percent used an OTC acid-reducing agent including OTC PPIs.

The study appearing in the May 2006 issue of JAIDS was a randomized, open-label, 2-arm, 3-period, drug-drug interaction study in 56 healthy adults. Subjects received 20 mg of esomeprazole alone for seven days followed by the addition of 1400 mg LEXIVA BIDor 700 mg LEXIVA boosted with 100 mg ritonavir (r) BID for 14 days at the same time with their dose of esomeprazole. This was followed by a 21- to 28-day washout period and then participants were given unboosted or boosted LEXIVA for 14 days. Results indicated that blood levels of LEXIVA were not changed when taken simultaneously with esomeprazole compared to LEXIVA administered without esomeprazole. Blood levels of esomeprazole were increased by 55 percent when taken with 1400 mg LEXIVA BID.

LEXIVA was co-discovered by GlaxoSmithKline and Vertex Pharmaceuticals Incorporated. It is the first PI to offer flexible dosing options (for PI-naïve patients) with no food or water restrictions.

Proton pump inhibitors such as esomeprazole reduce levels of stomach acid and are used to treat several stomach problems including heartburn. Over-the-counter antacids also reduce levels of stomach acid and, when co-administered with LEXIVA, did not significantly affect the blood levels of LEXIVA.

Important Prescribing and Safety Information

LEXIVA is indicated in combination with other antiretroviral agents for the treatment of HIV infection in adults. The PI-experienced patient study was not large enough to reach a definitive conclusion that LEXIVA/ritonavir and lopinavir/ritonavir are clinically equivalent. Once-daily administration of LEXIVA/ritonavir is not recommended for PI-experienced patients. LEXIVA does not cure HIV or prevent passing HIV to others.

You should not take LEXIVA if you have had an allergic reaction to LEXIVA or AGENERASE® (amprenavir). High blood sugar, diabetes or worsening of diabetes, and bleeding in hemophiliacs have occurred in some patients taking protease inhibitors. 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. The cause and long-term health effects of these conditions are not known at this time. Skin rashes can occur in patients taking LEXIVA. Rarely, rashes were severe or life threatening. Opportunistic infections can develop when you have HIV and your immune system is weak. It is very important that you see your healthcare provider regularly while you are taking LEXIVA to discuss any side effects or concerns. Most common side effects in clinical studies were diarrhea, headache, nausea, rash, and vomiting. In most cases, these side effects did not cause people to stop taking their medicine.

For full prescribing information for LEXIVA, please visit www.treathiv.com.

IMPORTANT INDICATION LANGUAGE

LEXIVA is indicated for the treatment of HIV infection in adults in combination with other antiretroviral medications. The following points should be considered when initiating therapy with LEXIVA plus ritonavir (RTV) (LEXIVA/r) in PI-experienced patients: the PI-experienced patient study was not large enough to reach a definitive conclusion that LEXIVA/r and lopinavir/ritonavir are clinically equivalent. Once-daily administration of LEXIVA plus RTV is not recommended for PI-experienced patients.

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.

Nexium is a registered trademark of the AstraZeneca group of companies.

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