Watson Pharmaceuticals Inc. said it won Food and Drug Administration approval to sell a new once-daily treatment for mild to moderate high blood pressure. Watson said it expects to begin selling the drug, Microzide, in the first quarter. Microzide is the first branded drug that Corona-based Watson has developed. The introduction of Microzide will be supported by a team of 60 salespeople, Watson said. Microzide is a diuretic type of hypertension drug. The U.S. market for diuretic hypertension drugs is expected to reach $500 million in 1997, Watson said. Watson's shares rose 37.5 cents to close at $44 on Nasdaq.