U.S. regulators have approved a simple, one-dose treatment to prevent relapses of Plasmodium vivax malaria. One dose of GlaxoSmithKline’s Krintafel (tafenoquine) prevented relapses in three-in-four patients. Antimalarial drugs can cure the initial malaria infection, but parasites can get into the liver, hide in a dormant form, and cause recurrences months or years later. A second drug is used to stop relapses.
Krintafel is an 8-aminoquinoline derivative, known as tafenoquine. Data analysed from a total of thirty-three studies -- involving more than 4,000 trial subjects exposed to the 300mg single-dose, and other doses of tafenoquine -- were effective against all stages of the P. vivax lifecycle, including hypnozoites -- the dormant version of the parasite that resides in the liver. Scientists at the Walter Reed Army Institute of Research first synthesised tafenoquine in 1978. In 2008, GSK entered into a collaboration with the not-for-profit drug research partnership, MMV, to develop tafenoquine as an anti-relapse medicine for patients infected with P. vivax. GlaxoSmithKline plans to apply for approval in Brazil, then other countries where P. vivax malaria is prevalent. It says it will sell the pills at low cost in developing countries.