The Medicines

A Need for Medicines

Neglected Tropical Diseases

Mectizan® (ivermectin)—donated by Merck & Co., Inc., Rahway, N.J., U.S.A.*—was the first drug donated for the control and elimination of a neglected tropical disease.

Before Mectizan, the only safe and effective intervention for river blindness was vector control, achieved by aerial larviciding of the rivers where the blackflies that transmit the disease breed. Similarly, the co-administration of Mectizan and albendazole—donated by GlaxoSmithKline (GSK)—was recommended by the World Health Organization (WHO) for the elimination of lymphatic filariasis (LF) in African countries where the disease is co-endemic with river blindness.

A Safe and Effective Treatment for River Blindness

Mectizan Proven To Be Effective

In the late 1970s, Nobel laureate Dr. William Campbell of Merck Research Laboratories (MRL) suggested the use of ivermectin (later named Mectizan) for river blindness (also called onchocerciasis) in humans. Following the breakthrough lab work by Dr. Campbell, another MRL researcher, Dr. Mohammed Aziz, championed the clinical development of Mectizan. Dr. Aziz led the collaboration with WHO in the early 1980s to design and implement field studies in West Africa that ultimately proved the effectiveness of the drug against river blindness. In 1987, Merck committed to donate Mectizan—as much as needed for as long as needed—for the control, and ultimately for the global elimination, of river blindness.

In 1998, Merck expanded the donation of Mectizan to be co-administered with GSK’s donation of albendazole for the elimination of LF in African countries and Yemen where river blindness and LF co-exist. 

Eliminating Lymphatic Filariasis (LF) where River Blindness & LF are Co-endemic

Mectizan (ivermectin) & Albendazole

In Yemen and African countries where river blindness and LF are co-endemic, DEC is not considered a safe treatment due to its potential for severe ocular side effects. In these countries, Merck donates Mectizan to be co-administered with albendazole, donated by GSK, for LF elimination. A single annual dose of the two drugs has been found to effectively reduce microfilaremia for one full year after treatment. This regimen was designed to interrupt disease transmission after five rounds to a level that will result in elimination of the disease as a public health problem.  

Mectizan is effective against river blindness and LF because it kills the juvenile parasites (microfilariae) produced by the adult worm, thereby reducing and eventually suppressing the patient’s microfilarial load. Following a single-dose regimen, the microfilariae reduction is maintained for 12 months in river blindness- and/or LF-infected persons. The drug produces only mild, short-lived post-treatment effects in some individuals (e.g., itching, swollen lymph nodes, fever, etc.). This unique profile makes Mectizan well suited for annual, large-scale, mass treatment programs for the elimination of river blindness and LF.

IDA or "Triple Therapy"

Ivermectin, DEC, and Albendazole

In 2017, in response to the new WHO-issued guidelines for “triple therapy”—ivermectin, diethylcabamazine (DEC), and albendazole—Merck further expanded its donation of Mectizan with up to 100 million treatments annually through 2025 to accelerate elimination of LF in countries where river blindness is not endemic. Known as “IDA,” the new strategy is implemented through the co-administration of ivermectin (Mectizan), DEC, and albendazole. GSK and Eisai are donating albendazole and DEC, respectively. The Mectizan Expert Committee published a set of guidelines designed to ensure fair and transparent allocation of this donation. 

*Merck & Co., Inc., Rahway, N.J., U.S.A., is known as MSD outside of the United States and Canada.