* Alza Corp., of Palo Alto, Calif., received marketing clearance from the FDA for Ditropan XL, a once-a-day treatment for overactive bladder. The drug combines conventional oxybutynin with Alza's Oros delivery technology. Alza entered into a deal in which Synthelabo SA, of Montrouge, France, will commercialize the product in Europe.

* Aquasearch Inc., of Kailua-Kona, Hawaii, signed a drug-discovery collaboration with EnzyMed Inc., of Iowa City, Iowa. Microalgae provided by Aquasearch will be screened for potential pharmaceutical applications, with the companies sharing revenues from any resulting commercialization of libraries.

* Corvas International Inc., of San Diego, and Schering-Plough Corp., of Madison, N.J., extended their collaboration in oral anticoagulants based on inhibitors of protease enzymes in the blood-clotting process. Schering-Plough will continue to support preclinical development and provide another $3 million to Corvas. The companies also are working together in the area of hepatitis C.

* Immunomedics Inc., of Morris Plains, N.J., said the FDA approved its new manufacturing facility and process for CEA-Scan, a product to diagnose colorectal cancer.