Shares in Paratek were up almost a third in premarket trading this morning after Bloomberg said the company, gearing up to file a new antibiotic, is considering a sale.

Last month, Paratek said a phase 3 trial of an oral-only omadacycline regimen hit its efficacy objectives—matching Pfizer's standard therapy Zyvox (linezolid) in skin and soft tissue infections—with the company saying it is planning a rolling regulatory submission to the FDA starting December of this year.

Nausea and vomiting side effects in the trial raised a few eyebrows, but the company insisted physicians and patients will be comfortable with the trade-off for efficacy. Meanwhile, the positive data backed up two earlier phase 3 trials and set up a dual filing for community-acquired pneumonia and skin infections, taking in both oral and intravenous formulations of the drug.

The newswire suggested Paratek was exploring strategic options—including a sale—and received takeover interest from multiple large drugmakers, citing people familiar with the situation. Bloomberg also said no firm decision had been taken but that Paratek retained advisors to help it assess its options.

It's not the first time Boston-based Paratek has been the subject of M&A speculation, with a Financial Times report in May also suggesting it could be subject to a takeover attempt. That suggested Allergan, already Paratek's partner for acne treatment sarecycline, had already put an offer on the table.

Sarecycline is also on course for filing before yearend after two positive phase 3 trials but would be a much smaller product than omadacycline—which has been tipped as a blockbuster given the pressing need for new antibiotic therapies. Aside from Allergan, Bayer, Merck and Novartis have all at one time worked with the biotech, but have all since dropped out.

On Paratek's second-quarter conference call late last month CEO Michael Bigham pointed to the achievement of developing a once-daily oral antibiotic, saying these have "historically been the purview of large pharma companies only ... and large pharma has not developed such a drug in almost a generation."

"It is important to remember that a once-daily oral only dosage regimen is a hallmark of the most successful blockbuster antibiotics," he said.

Paratek is also confident it will be able to secure favorable pricing for the antibiotic if approved, particularly as oral omadacycline can cut costs by allowing patients to be discharged from hospital early and in some cases avoid hospitalization altogether.