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NAC (N-acetyl-L-cysteine)

Cysteine itself and several derivatives thereof, as S-carboxy methyl-cysteine or N-acyl-cysteine, are already known in therapy and cosmetology. N-acetyl-cysteine (NAC) is a compound endowed with several useful pharmacological properties, making it a widely used drug. N-acetyl cysteine is a popular pharmaceutically active ingredient which dissolves or reduces the viscosity of mucous as produced in the respiratory airways, and including not only the lung tree but all the upper airways including the cavities in the forehead and the cheeks, to prevent or treat sinusitis, to thereby eliminate or reduce the symptoms of virus infections causing rhinitis, bronchitis and other respiratory tract congestion. N-acetyl-L-cysteine has been used as a therapeutic agent against e.g. chronic bronchitis for over 20 years. N-acetyl-cysteine is a critical substrate for glutathione GSH synthesis which has direct antioxidant properties and therefore along with glutamine, is a rate limiting factor in GSH production. NAC also appears to have endothelial derived relaxing factor properties, as well as protective properties and may, therefore, improve microvascular blood flow. N-acetyl-L-cysteine has been used extensively, primarily against obstructive lung disease like chronic bronchitis claimed to act as a mucolytic. In addition, this compound has been used as an antidote against liver toxicity caused by paracetamol overdose. N-acetyl cysteine can also be used as a scavenger to prevent cell death due to free radicals, and to prevent nitrate intolerance following chronic treatment with nitroglycerine and sustained release nitrate formulations. N-acetyl cysteine also has value as a nutritional supplement. N-acetyl-cysteine is a relatively strong acid and cannot be directly applied to the ocular surface as such, but only after being suitably neutralised.

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