Johnson & Johnson said that U.S. regulators have approved its new type of blood thinner shown to reduce deadly blood clots in patients who have undergone knee and hip replacements, according to the Associated Press. The Food and Drug Administration decision makes rivaroxaban the first U.S.-approved drug that works by blocking a clotting protein called factor Xa. That''s in contrast to older blood thinners that work by preventing platelets from sticking together. The once-a-day pill will serve as an alternative to the popular injection Lovenox, which is the standard treatment for patients who have undergone orthopedic surgery. Rivaroxaban had greater efficacy than Lovenox in head-to-head trials, and similar rates of side effects such as major internal bleeding. J&J said its new drug would be priced similarly to Lovenox, which is marketed by French drugmaker Sanofi-Aventis SA.