his calming and sleep-inducing substance is probably the most frequently prescribed drug in the benzodiazepine class. Alprazolam is used ainly to help persons suffering from panic attacks and other anxiety disorders, but it is not recommended for posttraumatic stress disorder. The compound can dramatically lessen premenstrual syndrome (PMS) and is routinely iven to women of child-bearing age. Improvement of PMS is not invariable, owever, and two careful experiments yielded results showing little benefit. Theoretical reasons and results from a rat experiment suggest that alprazolam may help maintain bone mass. That action may be especially important to athletes and elderly women, who commonly suffer loss of bone mass—an affiiction making breakage easier.