A new patient visited Northwestern University sex therapist Karen Donahey last week. She was a married 50-something woman troubled enough to make an appointment. Her husband had just filled a prescription for Viagra, the impotency drug that has either prompted frank and widespread discussion of an important men's health issue or further eroded moral values, depending on who is doing the listening.

During three weeks on the market, Viagra has ruffled more than a few bedroom routines, especially those once more sleepy than sexy. The drug is proving beyond satisfactory to most men who have tried it, many medical experts say. And the same goes for shareholders of skyrocketing Pfizer Inc. stock.

As the Viagra frenzy continues, complete with questions about a potential black market and about insurance coverage, behind it all are more basic questions about aging and sex in American culture. The issues range from what defines a normal sex life after age 40 to what exactly constitutes impotence. Will a drug that purports to cure a widespread sexual problem alter expectations for Americans in their later years? Will it change, for better or worse, the dynamics of long-term marriages? And will it ultimately be a boon to women as well as their mates?