Two New Antibiotics Show Efficacy in Gonorrhea Treatment

Nancy A. Melville

July 16, 2013

Two novel antibiotic combinations of existing US Food and Drug Administration (FDA)-approved drugs show efficacy in the successful treatment of gonorrhea, offering urgently needed new options as antibiotic resistance continues to narrow the arsenal for treatment of the sexually transmitted disease.

According to a phase IV clinical trial conducted by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH), 240 mg of injectable gentamicin, combined with 2 g of oral azithromycin, showed 100% effectiveness in curing genital gonorrhea infections, while 320 mg of oral gemifloxacin, combined with 2 g of oral azithromycin, was close behind, with a 99.5% treatment efficacy.

The combinations were each also effective in curing 100% of infections of the throat and rectum.

The treatment regimens were not without side effects, however — in each arm of the trial, about a third of patients experienced gastrointestinal issues, prompting the CDC to stand by its current gonorrhea treatment guidelines recommending only injectable ceftriaxone in combination with either azithromycin or doxycycline as a first-line treatment regimen offering few side-effects.

"These trial results are an exciting step in the right direction in the fight against drug-resistant gonorrhea," said Gail Bolan, MD, director of CDC's Division of STD Prevention, in a press statement.

"But patients need more oral options with fewer side effects. It is imperative that researchers and pharmaceutical companies prioritize research to continue to identify new, effective, better-tolerated drugs and drug combinations."

The study was sponsored by the NIH's National Institute of Allergy and Infectious Diseases (NIAID) and included 401 men and women aged 15 to 60 years with untreated gonorrhea infection, who were enrolled at 5 sites around the country.

Among 202 subjects enrolled in the gentamicin/azithromycin arm, side effects included nausea in 28% of subjects, diarrhea in 19%, and either abdominal discomfort or pain or vomiting in 7%.

Among 199 participants in the gemifloxicin/azithromycin arm of the study, 37% experienced nausea, 23% had diarrhea, and 11% had abdominal discomfort or pain.

The study is the first to evaluate the drugs as combination therapy for gonorrhea, and is to be presented this week at the 20th Meeting of the International Society for Sexually Transmitted Diseases Research (ISSTDR), in Vienna, Austria.

The CDC says it is considering the trial's findings for possible inclusion in future treatment guidelines, and suggests in the meantime that the alternative regimens may be useful options among patients who cannot be treated with ceftriaxone, such as those with severe cephalosporin allergy.

With antibiotic resistance becoming a pressing concern for gonorrhea, NIAID director Anthony S. Fauci, MD, underscored the urgent need to continue to explore effective alternatives.

"In addition to developing new treatment options, additional measures to stay ahead of resistant gonorrhea are critical," he said in a press statement.

"For example, a point-of-care drug susceptibility test would help providers know — at the time of diagnosis — which treatment regimen will be most effective. Progress toward a vaccine is urgently needed."

Sex Transm Infect. 2013;89:A14-A15. Abstract


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