Influence of N-acetylcysteine on hepatic amino acid metabolism in patients undergoing orthotopic liver transplantation

N-Acetylcysteine Infusion Improves Hepatic Perfusion in the Early Stages of Systemic Sclerosis

The aim of our study is to evaluate portal and hepatic hemodynamic changes after N-acetylcysteine infusion in patients with systemic sclerosis. In an open-label study 40 patients with Systemic Sclerosis (SSc) were treated with 15mg/kg/hour intravenous N-acetylcysteine for 5 consecutive hours in a single day. Hepatic flow volume, congestion index, portal flow volume, resistance index and pulse rate index were measured in each subject before and after infusion. In all patients mean hepatic flow volume (HFV) and mean portal flow volume (PFV) values after the five-hour infusion with NAC increased not significantly. In 22 selected patients with active capillaroscopic pattern, modified Rodnan Total Skin Score (mRTSS) <18 and mild-moderate score to vascular domain of disease severity scale (DSS), mean HFV increased significantly when compared with mean HFV of 18 SSc patients with late capillaroscopic pattern, mRTSS >18 and severe-end stage score to vascular domain of DSS. The results of our study demonstrate that NAC is able to increase HFV and total liver perfusion after a single infusion in SSc patients with low disease activity and severity scores.

Clinical results of N-acetylcysteine after major hepatic surgery: a review

BACKGROUND/PURPOSE

Ischemia/reperfusion injury is thought to play an important role in postoperative liver dysfunction and morbidity following major liver surgery. N-acetylcysteine may be protective by serving as a precursor to glutathione and replenishing intracellular stores, in addition to other mechanisms. The purpose of this review is to summarize the clinical evidence that N-acetylcysteine may reduce liver dysfunction and the postoperative complications following major liver surgery.

METHODS

A PubMed (MEDLINE) search was performed using the search terms "N-acetylcysteine", "Mucomyst", "liver", and "surgery" to identify all relevant articles published in English prior to February 2007.

RESULTS

Seventy-three articles were identified, and of these, there were seven studies that involved human patients undergoing orthotopic liver transplantation (six randomized controlled trials and one retrospective study).

CONCLUSIONS

The evidence that routine use of N-acetylcysteine reduces ischemia/reperfusion injury and prevents complications after major liver surgery is not conclusive. The available studies may have been limited by small sample sizes, and heterogeneous outcome measures prevent conclusions being made across studies and prevent pooling of the data. Further study with more relevant clinical endpoints and larger sample sizes is warranted.

N-acetylcysteine -- passe-partout or much ado about nothing?

In experimental studies, the old mucolytic agent N-acetylcysteine (NAC) has had beneficial effects in disorders supposedly linked to oxidative stress. Numerous, mainly small clinical trials with variable doses have yielded inconsistent results in a wide variety of diseases. NAC added to the conventional therapy of human immunodeficiency virus infection might be of benefit; in respect of chronic obstructive pulmonary disease, systematic reviews and meta-analyses suggested that prolonged treatment with NAC is efficacious, but a recent multicentre study has questioned this. In a large intervention trial on cancer recurrence, NAC was ineffective. NAC infusions have been widely used in acute hepatic failure but convincing evidence of its benefits is lacking. A preliminary study reported that NAC is effective in preventing radiocontrast-induced nephropathy but thereafter highly mixed results have been published, and even meta-analyses disagree on its efficacy. In intensive care NAC has mostly been a disappointment but recently it has 'given promises' in surgery with cardiopulmonary bypass. NAC therapy is routine only in paracetamol intoxication.

N-Acetylcysteine Use in Ischemic Hepatitis

We describe a case of antidepressant-induced ischemic hepatitis that responded to intravenous administration of N-acetylcysteine. Cytoprotection in the setting of ischemic hepatitis may be a therapeutic effect of N-acetylcysteine.

A Clinical and Pharmacoeconomic Justification for Intravenous Acetylcysteine

Paracetamol (acetaminophen) poisoning remains the most common exposure reported to US poison information centres and the leading cause of poisoning-related fatalities, despite the availability of an effective antidote, acetylcysteine. Oral acetylcysteine solution has been approved for the management of acetaminophen poisoning in the US for four decades. Until the recent approval of intravenous acetylcysteine in the US, it was necessary to compound the oral solution for intravenous administration. The effectiveness and tolerability of oral and intravenous acetylcysteine for the prevention of hepatotoxicity induced by paracetamol poisoning are well established in the literature. Intravenous acetylcysteine may be preferred over oral administration based on improved tolerability, ease of administration and the shortened course of therapy (20 hours intravenous vs 72 hours oral). The two intravenous acetylcysteine regimens documented in the literature, 48 hours and 20 hours, have similar efficacy when started within 8-10 hours of ingestion. Although there are no legal concerns with continuing the routine compounding of the oral solution to an intravenous product, new standards for pharmacy compounding of sterile preparations set forth by the US Pharmacopoeia highlight that the risk of compounding products for intravenous use must be assessed carefully. Changing the route of administration of a sterile oral solution to an intravenous preparation, when a commercial sterile and pyrogen-free product is available, may not be advisable. The best cost-containment strategies must be used for introduction of the more costly sterile, pyrogen-free intravenous acetylcysteine formulation by hospitals and healthcare systems. The intravenous acetylcysteine product is more cost effective when given for 20 hours than other treatment protocols based on the costs of acetylcysteine and hospitalisation. If used per protocol, the 20-hour intravenous acetylcysteine regimen may decrease hospital length of stay, thereby, offsetting the increased drug cost. Data conflict on the efficacy and administration of intravenous acetylcysteine for off-label uses, such as radiographic contrast media-induced nephropathy prevention and reperfusion in orthotopic liver transplantation. The costs for the intravenous formulation for these indications is significantly higher than use of the oral formulation for oral administration in radiographic contrast media-induced nephropathy prevention and compounded for intravenous use in orthotopic liver transplantation. The oral solution should be retained by healthcare systems for oral and inhalation applications, such as respiratory conditions, oral administration for radiographic contrast media nephropathy prevention, or the use of the 72-hour oral protocol to treat paracetamol poisoning, when the intravenous preparation cannot be used.