CINCINNATI (AP) - Procter & Gamble Co. has received federal approval to market Actonel, its drug for prevention and treatment of osteoporosis. Actonel, which received Food and Drug Administration approval Monday, faces some well-established competition in the lucrative market, which is quickly expanding as the baby boom generation ages. Merck & Co.'s Fosamax, also sold as a prevention and treatment medication for osteoporosis, has been on the market five years. It had sales of $1.06 billion last year and has been used by more than 3.5 million patients. And in September, the FDA approved Eli Lilly & Co.'s Evista as an osteoporosis drug.