What sort of research and development programs existed for medical technology and substances? What kind of diseases were they most focused on curing? Were there any notable successes or failures?
It might help if you narrowed down your question a little. The Soviet era is a solid seventy years, which is a very long time when you're talking about scientific advances in the 20th century. The answers to your questions will be very different directly post-revolution versus WWII versus the Cold War (which itself is almost 40 years)
From what I know the Soviet Union was responsible for some pioneering research. Vladimir Demikhov in particular pioneered the transplantation of heart, lung and head in animals. Gavriil Ilizarov developed external fixation for complicated fractures (Ilizarov apparatus) in the 1950s. It was borrowed in the West only in the 1980s when the Italian journalist Carlo Mauri got medicated in the Soviet Union.