Wyeth ( WYE ) Friday said the Food and Drug Administration granted priority review status to its experimental antibiotic Tygacil. Tygacil is the first in a new class of antibiotics, and it is being aimed at serious and complicated infections or against bacteria that have developed a resistance to other antibiotics. In its peak year, analysts estimate the drug could be a $1 billion product. A priority designation is applied to a drug that, if approved, would be a significant improvement compared with existing treatments. FDA review takes about half the time of the normal 12-month period. Wyeth is seeking market approval for Tygacil as a treatment for patients with complicated intra-abdominal infections and complicated skin and skin structure infections. The New Jersey-based drugmaker reports fourth-quarter earnings Monday. Shares ended at $42.67 Thursday.