Monalazone

Monalazone, used as monalazone disodium (INN; the disodium salt) and sold under the brand names Naclobenz-Natrium, Spergisin, and Speton, is a vaginal disinfectant or antiseptic and spermicidal contraceptive. It is a sulfonylbenzoic acid derivative and is closely related structurally to halazone. The compound was synthesized in 1937. A vaginal tablet combination of 0.125 mg estradiol benzoate and 10 mg monalazone was previously marketed under the brand name Malun 25.