Some 10 years ago, Russians who were ill usually opted to treat themselves by choosing from a tightly restricted selection of mostly locally produced medicines available at the country's drugstores. Now, with thousands of imported drugs flooding the pharmaceutical market, Russians are facing a new problem - how not to get lost among the enormous variety of new medicines available. How Russian patients and doctors educate themselves about the new brands of drugs hitting the market is one of the issues being discussed this week at the seventh annual Chelovek i Lekarstva, or ""Man and Medicine"" congress, which opened Monday. ""Russia today is experiencing a boom in imported medicines,"" said Gleb Fedoseyev, a professor at St. Petersburg Medical University, addressing the congress Tuesday. ""Doctors face colossal difficulties in using and prescribing some drugs.