21 CFR § 333.320 Topical Antimicrobial Drug Products for Over-the-Counter Human Use§ 333.320 Permitted combinations of active ingredients.Current through Sep 8, 2026 · Read all of Part 333(a) Resorcinol identified in § 333.310(b) may be combined with sulfur identified in § 333.310(f). (b) Resorcinol monoacetate identified in § 333.310(c) may be combined with sulfur identified in § 333.310(f). [75 FR 9776, Mar. 4, 2010]