Acetilcisztein

Acetilcisztein, known in English as N-acetylcysteine (NAC), is a thiol-containing derivative of the amino acid cysteine. It is used in medicine as a mucolytic agent and as an antidote for acetaminophen (paracetamol) poisoning, and it also serves as a precursor to the antioxidant glutathione.

Pharmacology and mechanism: NAC replenishes hepatic glutathione stores and acts as a scavenger of reactive oxygen species. Its thiol group reduces disulfide bonds in mucus, lowering viscosity and aiding mucus clearance from the airways.

Medical uses: The most established indication is treatment of acetaminophen overdose, where NAC prevents or mitigates liver injury when given promptly. It is also used as a mucolytic in respiratory diseases with thick secretions, such as chronic bronchitis, COPD, bronchiectasis, and cystic fibrosis. In other conditions, its use is more limited and guided by clinical judgment and local guidelines.

Safety and adverse effects: Common adverse effects include nausea, vomiting, and abdominal discomfort. Intravenous administration can cause hypersensitivity reactions, including flushing, rash, or, rarely, anaphylactoid reactions. Oral NAC often has a sulfurous taste and odor and can cause GI upset. Caution is advised in patients with asthma, significant kidney impairment, or those taking other medications as advised by a clinician.

Availability and regulation: NAC is available by prescription in many countries for overdoses and as a mucolytic, and is sold as an over-the-counter supplement in others. Dosing and duration depend on the indication, patient factors, and local medical guidelines.