As part of the company's ongoing commitment to the fight against HIV/AIDS, Merck has researched and developed the following pediatric formulations for its ARVs, one of which, ISENTRESS^® (raltegravir), remains under development at this time.

ISENTRESS: In 2007 Merck initiated in collaboration with the National Institute of Allergy and Infectious Diseases, the National Institute of Child Health and Human Development, and the International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) Group, a Phase I/II, multicenter, open-label, noncomparative study to evaluate the safety, tolerability, pharmacokinetics and antiretroviral activity of ISENTRESS in children and adolescents. The trial involves HIV infected children ranging from 4 weeks to 18 years of age in the United States, Latin America, and Africa.

This is a study of three formulations: the adult tablet, an investigational chewable tablet, and an investigational granule formulation for oral suspension. The study is being conducted in two stages. The first stage is designed to collect intensive pharmacokinetics and short-term safety data in order to make a dose selection. The second stage will provide data on safety and efficacy at the selected dose with chronic use over 48 weeks, and will include collection of additional pharmacokinetics data. There is a protocol extension to five years.

Preliminary results from the study have been presented at several scientific meetings, including the Conference on Retroviruses and Opportunistic Infections (2009, 2010, 2011), Interscience Conference on Antimicrobial Agents and Chemotherapy (2008, 2009) and the International Workshop on Clinical Pharmacology of HIV Therapy (2008). Merck is dedicated to continuing the work necessary to obtain regulatory approval for the pediatric formulation of ISENTRESS.

STOCRIN^® (efavirenz): is indicated for the treatment of HIV-1 infection and has pediatric indications (for patients ages three to 17 years) in many countries, particularly in the developing world. For those countries for which Merck has the right to distribute STOCRIN under our agreement with Bristol-Myers Squibb, we are currently marketing four formulations: STOCRIN oral solution, STOCRIN 50mg, STOCRIN 200mg and STOCRIN 600mg tablets.

CRIXIVAN^® (indinavir): is indicated for the treatment of HIV-1 infection and has pediatric indications in many countries, particularly in the developing world. CRIXIVAN has not been evaluated in children under three years of age.

Merck is also working in partnership with the U.S. President's Emergency Plan for AIDS Relief (PEPFAR), Partnership for Pediatric AIDS Treatment, to identify scientific and technical solutions to improve access to ARV treatment for children living with HIV in resource-limited settings. Participating in this effort are the U.S. Government, multilateral organizations such as the United Nations Children's Fund (UNICEF) and the United Nations Joint Programme on HIV/AIDS (UNAIDS), research-based pharmaceutical companies and generic drug companies. The partners have committed to work toward identifying scientific obstacles to treatment, share best practices and take concrete practical steps to address barriers to access.