A Comprehensive Monograph on Acetylcysteine (N-Acetyl-L-cysteine)

Introduction and Drug Profile

Executive Summary

Acetylcysteine, more commonly known by its abbreviation NAC, is a small molecule drug derived from the naturally occurring amino acid L-cysteine. First approved by the U.S. Food and Drug Administration (FDA) on September 14, 1963, it has carved out an indispensable niche in modern medicine with a remarkable dual identity.[1] On one hand, it is a cornerstone of acute care, serving as a life-saving antidote for acetaminophen poisoning and as a potent mucolytic agent for patients with debilitating respiratory conditions.[1] In these roles, its mechanisms are well-defined and its clinical efficacy is undisputed. On the other hand, Acetylcysteine has emerged as a compound of immense interest in clinical research, investigated for a vast and diverse array of off-label indications. This second identity is driven by its complex biological activities as a powerful antioxidant, a modulator of inflammation, and a regulator of glutamatergic neurotransmission in the central nervous system.[4] This report provides an exhaustive, evidence-based monograph on Acetylcysteine, synthesizing foundational chemical data, elucidating its multifaceted mechanisms of action, detailing its pharmacokinetic profile, outlining its clinical applications—both approved and investigational—and concluding with a thorough analysis of its safety, tolerability, and risk management strategies.

Drug Identification and Physicochemical Properties

A precise understanding of Acetylcysteine's chemical and physical properties is fundamental to appreciating its formulation, biological activity, and clinical handling.

Nomenclature and Identifiers