PHILADELPHIA — Dermatologist Albert M. Kligman, whose research led to discoveries including the acne and wrinkle drug Retin-A but whose pioneering work was overshadowed by his experiments involving prisoners, died Feb. 9 at age 93.

Kligman died of heart failure at Pennsylvania Hospital, his daughter Gail Kligman, a sociology professor at the University of California, Los Angeles, said Sunday.

Kligman is credited as being the first dermatologist to show a link between sun exposure and wrinkles. He coined the term "photoaging" to describe skin aging caused by the sun. In 1967, he patented Retin-A, a vitamin A derivative known generically as tretinoin, as an acne treatment and received a new patent in 1986 after discovering the drug's wrinkle-fighting ability.