Design strategy for circular/infinite navigation in android

Suppose we have a "User Info" screen. In this screen we list the friends of this user. When we tap a friend in the list, we navigate to this user's "User Info" screen. If we continue navigating like this, the activity back stack will be full of "User Info" activities, and eventually we'll get a "out of memory" exception. Is there any way we can prevent this to happen? What is the proper way of navigation in this situations?