Acetylcysteine: a drug with an interesting past and a fascinating future.

N-acetylcysteine (NAC) possesses a free sulfhydryl group that can rupture disulfide bridges. Although it is considered to be a mucolytic, its mucokinetic actions include expectorant, bronchorrheic and mucoregulatory contributions. New uses include the management of acetaminophen poisoning and the scavenging of free radicals liberated by cancer chemotherapy drugs. The antioxidant effects may be of prophylactic value in lungs at risk from smoking, pollution and infection. Other uses proposed for NAC include the therapy of connective tissue diseases and its use as a component in life extension diets.