Rintatolimod

Rintatolimod, sold under the tradename Ampligen, is a medication intended for treatment of chronic fatigue syndrome. However, there is only low-strength evidence that it can improve the ability to exercise.

It is an immunomodulatory double stranded RNA drug synthesized in the 1970s and manufactured by Hemispherx Biopharma.

Although Ampligen was cleared for use in Canada in 1997, and obtained orphan drug status for treatment of CFS in the European Union in 2000, it is so far without FDA approval, and therefore classed as experimental in the United States. In 2007, Hemispherx filed a New Drug Application (NDA) with the U.S. Food and Drug Administration (FDA) to market and sell rintatolimod for the treatment of CFS, but this was rejected in December 2009, because the FDA concluded that the two RCTs "did not provide credible evidence of efficacy" and "because of clinical, statistical, clinical pharmacology, nonclinical, product quality, and facilities inspection deficiencies." The FDA requested Hemispherx conduct at least one additional controlled trial to demonstrate efficacy in treating CFS. In August 2012, Hemispherx submitted further analyses of the original clinical trial data, but did not submit additional trials for review. Four months later, a committee of the FDA voted 8-5 against approval for rintatolimod, again citing insufficient data.

For people with chronic fatigue syndrome, there is low quality evidence that rintatolimod can improve their ability to exercise.

Rintatolimod is designed to boost cellular defenses against viruses and tumors, and can be used for avian influenza.

An independent review of rintatolimod trials in chronic fatigue syndrome was published in the December 2006 issue of the Journal of Clinical Virology. It concluded that Ampligen has been "generally well tolerated", with a "low incidence of clinical toxicity", particularly when compared with the toxicity of the diseases it is used to treat. "No serious safety issues have resulted from the administration of ~75,000 doses IV (most commonly 400 mg) twice weekly for up to one year periods or greater. Animal toxicity studies support this observation in humans, with primates demonstrating the greatest margin of safety." A mild flushing reaction has occurred in about 15% of patients, and more rarely reported side effects include chills, fever, malaise, leukopenia, neutropenia and leukocytosis. Some of these side effects may be attributed to a temporary Herxheimer reaction in response to pathogen die off. According to Hemispherx and patient testimonials, side-effects, when they occur, usually subside within three to four months or less.