N-Acetylcysteine

ACETADOTE, an FDA-approved intravenous acetylcysteine product under NDA 021539, has prescription marketing status and may be dispensed only on a practitioner's prescription under 21 U.S.C. § 353(b). Its label is a human prescription drug label bearing the designation ‘Rx only’, and DailyMed lists its DEA schedule as none. FDA considers NAC excluded from the statutory definition of a dietary supplement because acetylcysteine was approved as a new drug in 1963, but currently exercises enforcement discretion for certain otherwise lawful NAC products labeled as dietary supplements.

Health Canada classifies N-acetylcysteine products case by case. Its N-Acetyl-L-Cysteine monograph provides a product-licence pathway for oral natural health products; the monograph limits that route to oral use and its compendial adult quantity to no more than 600 mg per day. Those are conditions for using the monograph, not a substance-wide possession or sale threshold. The Licensed Natural Health Products Database lists a 600 mg oral capsule (NPN 80113725) as active and marketed. Section 4 of the Natural Health Products Regulations prohibits sale of a natural health product without a product licence and during a stop-sale, suspension, or after cancellation of its licence. Separately, the Drug Product Database lists acetylcysteine solution USP 200 mg/mL (DIN 02538431), for oral, inhalation, and intravenous administration, as a marketed human drug classified ETHICAL—an unscheduled, non-prescription professional-use classification. Section C.01.014 of the Food and Drug Regulations prohibits a manufacturer from selling a drug in dosage form unless its DIN has been assigned and remains in force. These NHP and ETHICAL classifications are product-specific: route, dosage form, claims, composition, and intended use can place different NAC products under different regulatory pathways.

Malaysia's current Poisons List names acetylcysteine and classifies all preparations for parenteral administration as Group C. Under section 22 of the Poisons Act 1952, their retail sale or supply is prohibited except where the transaction would be authorized under the Group B rules or the preparation is supplied as a dispensed medicine or an ingredient in one. The same schedule exempts all acetylcysteine preparations that are not in Group C, and section 7 provides that the Act does not apply to an exempted preparation. The route-based exemption does not establish that every nonparenteral acetylcysteine product is currently registered or marketed over the counter.

Singapore's National Drug Formulary identifies the HSA-registered FLUIMUCIL A 600 Effervescent Tablet 600 mg (OTC Pack), registration SIN15339P, as containing acetylcysteine 600 mg and classifies it as General Sale List. The Health Sciences Authority defines a General Sale List therapeutic product as obtainable from any retailer. This classification applies to the registered SIN15339P formulation and does not establish the classification of bulk acetylcysteine or every acetylcysteine formulation.