The Other Indication of N-acetylcysteine

Apart from being the antidote to paracetamol poisoning, N-acetylcysteine is also used for the prevention of nephropathy associated with radiographic contrast media. (For instance, before and after primary angioplasty for acute myocardial infarction to reduce the risk of contrast-induced nephropathy.)

When it is used for such indication, the dose is 600mg bd orally before and the day of contrast media administration (total of 4 doses) [cf antidote to paracetamol poisoning: 150mg/kg over 15 min, then 50mg/kg over 4h, then 100mg/kg over 16h intravenously]. This indication is not in the MOH Formulary hence Ketua Pengarah Kesihatan (KPK) application is required.

Contrast agents reduce renal function by altering renal haemodynamics and by exerting direct toxic effects on tubular epithelial cells. It is on the assumption that reactive oxygen species in the pathogenesis of acute contrast-agent–induced reductions in renal function that the effects of the prophylactic oral administration of the antioxidant acetylcysteine have been studied in various trials.

According to EBSCO, to date, the outcomes for the use of acetylcysteine in the prevention of contrast nephropathy is of level 2 (mid level) and level 3 (lacking direct evidence). For those who are interested in the summary of various trials from EBSCO, you may email me at bpharmer05[at]gmail[dot]com.


References

1. Tepel M, van der Giet M, Schwarzfeld C et al. Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine. N Engl J Med 2000; 343: 180-184.
2. Acetylcysteine. Dynamed-powered by EBSCOhost. 2010 May 8 [Accessed 2010 May 22]; Available from: URL: http://dynaweb.ebscohost.com/