Cempra Pharmaceuticals‘ bacterial pneumonia drug candidate was demonstrated to be just as effective as a currently available antibiotic and more important, it posed less risk of causing adverse reactions.

[The venture capital backed firm closed on $5 million in new funding last month.]

In announcing phase 2 clinical trial results for solithromycin on Thursday, the Chapel Hill-based biotechnology company said the efficacy of its drug candidate was comparable to the antibiotic levofloxacin. Also sold under brand names Levaquin and Tavanic, that drug is used to treat serious bacterial infections that are either life threatening or have not responded to other antibiotics.

But levofloxacin carries safety and toxicity risks. The drug can increase chances a patient will develop tendinitis or suffer a ruptured tendon, a risk that increases with age of a patient. The drug can also exacerbate muscle weakness in people who have the nervous system disorder myasthenia gravis. Those risks led the Food and Drug Administration to put a black box warning on the product.

Cempra’s research on macrolides, a class of compounds that has produced effective antibiotics, aims to develop new antibiotics to fight drug-resistant bacteria. Solithromycin, formerly known as CEM-101, is being studied as a treatment for community-acquired bacterial pneumonia (CABP). Besides the pneumonia indication, solithromycin is also expected to be effective against Legionnaires’ disease as well as sexually transmitted diseases such as syphilis.

Dr. David Oldach, Cempra’s senior vice president of clinical research, said in a statement that the company believes the data support progression of solithromycin into phase 3 trials. The full data will be presented at an upcoming scientific conference.

Cempra has another clinical stage antibacterial compound. Taksta is being developed to fight skin infections such as MRSA. Taksta is ready to enter clinical trials though the company has been looking for a pharmaceutical partner that could finance late-stage development of the compound. It’s possible that Cempra could also seek a partner for solithromycin.

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