Antibiotics developer Cempra’s (NASDAQ:CEMP) first quarter net loss widened to $10.3 million, compared to a net loss of just $3.5 million in the same period of 2012.

The wider loss came as the Chapel Hill company boosted R&D spending on two clinical stage compounds, including its lead antibiotics candidate solithromycin, currently in phase III trials in patients with community-acquired bacterial pneumonia.

“The first quarter of 2013 was one of ramping up for Cempra,” CEO Prabhavathi Fernandes said during a conference call to discuss results.

Cempra’s R&D expenses in the quarter ended March 31 totaled $7.4 million, an increase of 293 percent compared to the first quarter of 2012. The company said the R&D expense was primarily due to the start of the oral solithromycin phase III trial as well as the start of phase II studies of another compound, Taksta. That antibiotic is being studied in patients with prosthetic joint infections.

Cempra, which does not yet have any Food and Drug Administration approved products, expects R&D expenses to continue to increase due to the clinical trial work. But CFO Mark Hahn said Cempra has enough cash and equivalents to fund the company’s operations into 2015.