Ethel Siris, MD: If you need to take medication for your bones, the probability is you're going to need to be doing something for the rest of your life. Whether that something is that drug that you started with or not, remains to be determined. People who were told they had hypertension 10 years ago might have been put on a drug that three years later was changed to some other drug, and that's not at all unusual. As we learn more, as we develop even better drugs, we have good drugs, but as we develop even better drugs, we may be switching people from time to time. We may find that certain drugs, when given for a length of time can be stopped, and nothing further needs to be done for a period of time. We are learning as we go, but I think at a minimum, most of our clinical trials go through three years, four years. Some of our studies have extensions up to 8 to 10 years. We feel pretty comfortable giving people these drugs for a significant duration. They seem to work as long as they are taken. The question is when you stop 'em, how quickly do you lose the effect, and that differs from drug to drug. So when you stop estrogen, you quickly lose the effect. When you stop Evista, you quickly lose the effect. With the Actonel, Fosomax, Boniva, Reclast agents the loss of effect is slower, but it will depend on how long you took it, and which one you took as to how soon you're going to start to have bone loss again, and these are things we are still learning. But certainly, several years of use of these drugs appears to be very well tolerated and continues to be effective.