• Merck & Co. Inc. program reaches 20 million people in areas with onchocerciasis, or river blindness;
• Expanded program will also reach Africans at risk for lymphatic filariasis;
• The World Health Organization estimates that 300 million people in Africa are at risk of lymphatic filariasis.

WHITEHOUSE STATION, N.J., Oct. 22, 1998 /PRNewswire/ -- Merck & Co., Inc. (NYSE: MRK), announced today a major expansion of the program in Africa through which the drug Mectizan(R) (ivermectin, MSD) is donated to treat the parasitic disease onchocerciasis, or river blindness. This decision expands the donation within Africa to include lymphatic filariasis -- a disease for which, according to the World Health Organization, an estimated 300 million Africans are at risk and may need treatment each year -- in countries where lymphatic filariasis and other parasitic diseases (onchocerciasis or loaisis) are co-endemic.

The decision to expand the donation program was made after Merck received French regulatory approval this year for use of ivermectin to treat lymphatic filariasis.

The original Mectizan Donation Program is now in its eleventh year, with more than 20 million people being treated each year for onchocerciasis, or river blindness. The new program for lymphatic filariasis could increase that number dramatically.

In the United States, ivermectin is sold under the brand name Stromectol(R) for treatment of infection with nondisseminated intestinal threadworm (strongyloidiasis) and for treatment of the parasite that causes a condition known as river blindness (onchocerciasis). The drug is not indicated for the treatment of lymphatic filariasis in the United States.

The decision to expand the Mectizan Donation Program comes after research conducted by Merck in collaboration with the World Health Organization that demonstrated that Mectizan is effective against lymphatic filariasis. While lymphatic filariasis occurs throughout many parts of the world, the decision to donate Mectizan for lymphatic filariasis in Africa was based on the fact that diethylcarbamazine, or DEC, which is commonly used to treat the disease, cannot be widely used in Africa because it can cause severe side effects in patients who have either onchocerciasis or loaisis -- two diseases that are common in Africa.

"Merck's decision to expand our already successful Mectizan Donation Program is a logical and sensible step in providing this medicine to the many millions of people who suffer from -- or are at risk of developing -- lymphatic filariasis," said Merck Chairman and CEO Raymond V. Gilmartin. "The expanded use of Mectizan for lymphatic filariasis in Africa fits well with the existing program through which, for more than 10 years, Merck has donated Mectizan."

Merck's donation is part of a coordinated effort involving national health ministries, the World Health Organization, The World Bank, UNICEF, The Carter Center in Atlanta, Ga., USA, and numerous non-governmental organizations working in Africa.

Background on the Disease

Lymphatic filariasis, commonly known as elephantiasis, is a major parasitic disease resulting in serious social and economic burden. The World Health Organization estimates that nearly 1 billion people in 73 countries are at risk from lymphatic filariasis and over 120 million are infected.

Approximately one-third of those infected live in India, one-third in Asia and the Pacific, and one-third live in Africa. It is in sub-Saharan Africa that the prevalence of onchocerciasis and loaisis, and the reactions that can occur following treatment with diethylcarbamazine, makes a medication like Mectizan so important.

Lymphatic filariasis is transmitted by mosquitoes. The thread-like, parasitic filarial worms Wuchereria bancrofti and Brugia malayi that cause lymphatic filariasis live almost exclusively in humans. The worms lodge in the lymphatic system, the network of nodes and vessels that maintain the fluid balance in the tissues and blood, and an essential component of the body's immune system. They live for years, producing millions of immature microfilariae that circulate in the blood. To complete the life cycle, these microfilariae are picked up by mosquitoes which then transmit the disease to other humans.

Since the clinical manifestations of filarial diseases develop relatively slowly, some people with lymphatic filariasis can have the disease for many years without even being aware of it. Some of these individuals may develop kidney damage due to blockage of the lymphatic system. The reason that lymphatic filariasis is commonly known as elephantiasis is because the disease can lead to disfiguring enlargement of the arms, legs and genitals.

Current Treatment

While diethylcarbamazine alone has been used for more than 50 years to treat lymphatic filariasis, recent studies indicate that a combination of albendazole and DEC or albendazole and ivermectin is more effective, reducing microfilarial level in the blood by 99 percent. Recent studies also indicate that ivermectin alone reduces the microfilarial levels in the blood by more than 90 percent.

The World Health Organization currently recommends that lymphatic filariasis be treated with a combination of DEC plus ivermectin, DEC plus albendazole, or albendazole plus ivermectin. The WHO believes the effectiveness of these regimens makes them suitable for annual treatment designed to interrupt disease transmission with the hypothetical possibility of eliminating the disease.

In clinical trials of ivermectin in patients with strongyloidiasis and onchocerciasis, the drug was generally well tolerated. In trials on strongyloidiasis, the following adverse experiences occurred in greater than 1 percent of the patients: diarrhea (1.8 percent), nausea (1.8 percent), dizziness (2.8 percent) and pruritus [itching] (2.8 percent). In trials for onchocerciasis, some patients experienced allergic and inflammatory responses to the death of microfilariae. These adverse events included arthralgia/synovitis (9.3 percent), axillary lymph node enlargement and tenderness (11.0 and 4.4 percent, respectively), cervical lymph node enlargement and tenderness (5.3 percent and 1.2 percent, respectively), inguinal lymph node enlargement and tenderness (12.6 percent and 13.9 percent, respectively), other lymph node enlargement and tenderness (3.0 percent and 1.9 percent, respectively), pruritus (27.5 percent), skin involvement including edema, papular and pustular or frank urticarial rash (22.7 percent) and fever (22.6 percent). Ivermectin does not kill the adult Onchocerca parasites.

Merck's Decision to Donate Mectizan for Lymphatic Filariasis

Given the medical need for ivermectin to treat lymphatic filariasis in countries where there is concomitant onchocerciasis or loaisis, Merck decided to expand the Mectizan Donation Program beyond the treatment of onchocerciasis.

How the Donation Will Work

Merck plans to donate Mectizan for lymphatic filariasis through the same system successfully established for treating onchocerciasis. Mectizan will be donated and delivered to institutions including non-governmental development organizations (NGDOs) and ministries of health, in countries where lymphatic filariasis as well as onchocerciasis or loaisis occur.

Program is Supported by Key Organizations

WHO's Director-General, Dr. Gro Harlem Brundtland, welcomed the decision by Merck. "Merck's generous contribution will greatly strengthen the global coalition to fight lymphatic filariasis, and in particular the private sector representation in this coalition. It includes partners from the governments of endemic and non-endemic countries, international organizations of the United Nations family and a number of important non-government institutions -- all working together to overcome this debilitating disease and to improve the health of those served by this effort."

The World Bank has also endorsed Merck's decision to expand the Mectizan Donation Program in Africa.
Merck & Co., Inc. is a leading research-driven pharmaceutical company that discovers, develops, manufactures and markets a broad range of human and animal health products, directly and through its joint ventures, and provides pharmaceutical benefit services through Merck-Medco Managed Care.

SOURCE: Merck & Co., Inc.