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Potential new treatments for tough infections

September 14, 2009 |  2:44 pm

SwineIcon A combination of three antiviral drugs may be more effective at treating seasonal and novel H1N1 influenza compared with a single drug or two drugs, according to research presented today at the Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco. The study found that the triple therapy is also effective against drug-resistant flu strains.

The treatment, called TCAD, for triple combination antiviral drug, is a proprietary, fixed-dose combination of the drugs amantadine and ribavirin administered with the drug Tamiflu (oseltamivir). The study, from researchers from Adamas Pharmaceuticals, was performed in laboratory cultures, not in patients. The findings are somewhat surprising, however, because many seasonal flu strains have been found to be resistant to either the adamantane class of drugs or oseltamivir. It appears that, when combined, the drugs act synergistically to provide a higher level of antiviral activity than is seen in any of the medications alone.

"We're not quite sure how it works; how we derive synergy with the three drugs," said Amy Patick, vice president of research for Adamas.

The company is beginning phase-two clinical trials in patients with novel H1N1. Until further studies are completed, Patick discouraged use of the three drugs - which are already on the market - together to treat severe flu cases.

"I think that might not be the best idea," she said. "The dosages we have selected for clinical study are not the standard doses. We are proceeding with this unique formulation. . .and we'll study it as if it were a new drug."

In other news from the ICAAC meeting:

  • A phase-three study on a drug to treat traveler's diarrhea showed good results and could be on the market next year. Traveler's diarrhea causes diarrhea, cramps, nausea, fever and headache. About 85% of cases are caused by the bacteria E. coli, shigella, salmonella or campylobacter. Therapies exist to treat traveler's diarrhea, but some only work against specific bacteria or have side effects. The new drug, prulifloxacin, was tested in 133 travelers in Mexico, India and Guatemala while 135 patients received a placebo. The patients treated with prulifloxacin recovered from diarrhea faster than the patients taking a placebo. The manufacturer of the compound, Optimer Pharmaceuticals Inc. of San Diego, said it plans on filing a new drug application during the first half of next year.
  • A medication already on the market and approved for treating adults with community-acquired bacterial pneumonia may also be effective in treating methicillin-resistant staphylococcus aureus. The laboratory study of tigecycline (Tygacil) showed effectiveness against all multiple-drug-resistant strains of MRSA.

-- Shari Roan