***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background : Pharmacokinetic data suggests that the intravenous form of n‐acetylcysteine ( NAC ) may be more effective than the oral formulation in preventing contrast induced nephropathy ( CIN ) . NAC owing to its anti‐oxidant properties might be beneficial for patients with acute coronary syndromes ( ACS ) who are at increased risk for CIN . The aim of this prospect i ve r and omized , single‐center , double‐blind , placebo controlled trial ( NCT00939913 ) was to assess the effect of high‐dose intravenous NAC on CIN in ACS patients undergoing coronary angiography and /or percutaneous coronary intervention ( PCI ) . Methods : We r and omized 398 ACS patients scheduled for diagnostic angiography ± PCI to an intravenous regimen of high‐dose NAC ( 1,200 mg bolus followed by 200 mg/hr for 24 hr ; n = 206 ) or placebo ( n = 192 ) . The primary end‐point was incidence of CIN defined as an increase in serum creatinine concentration ≥25 % above the baseline level within 72 hr of the administration of intravenous contrast . Results : There was no difference found for the primary end point with CIN in 16 % of the NAC group and in 13 % of the placebo group ( p = 0.40 ) . Change in serum cystatin‐C , a sensitive marker for renal function , was 0.046 ± 0.204 in the NAC group and 0.002 ± 0.260 in the control group ( p = 0.07 ) . Conclusion : In ACS patients undergoing angiography ± PCI , high‐dose intravenous NAC failed to reduce the incidence of CIN . © 2011 Wiley Periodicals , BACKGROUND Contrast-induced nephropathy ( CIN ) is a leading cause of acute renal failure and affects mortality and morbidity . We investigated the efficacy of prophylactic intravenous ( IV ) N-acetylcysteine ( NAC ) and hydration for the prevention of CIN in patients with mild to moderate renal dysfunction who are undergoing coronary angiography and /or percutaneous coronary intervention ( PCI ) . METHODS A total of 220 patients who had mild to moderate renal dysfunction with serum creatinine ( SCr ) ≥ 1.1mg/dL or creatinine clearance ≤ 60 mL/min were r and omized in 3 groups : 80 patients were assigned to IV NAC plus high-dose hydration with normal saline , 80 patients to only high-dose hydration with normal saline and 60 patients to st and ard hydration with normal saline ( control group ) . The primary end point was the alteration of SCr level . The secondary end point was the development of CIN after the procedure . RESULTS SCr levels changed the least in the NAC plus high-hydration group ( P=0.004 ) . The rate of the CIN in the NAC plus high-dose hydration group was also lower than the high-dose hydration group ( P=0.006 ) . No significant differences in the primary and secondary end points were found between high-dose hydration and control group . CONCLUSION The results of this study suggest that NAC plus high-dose hydration was superior to high-dose hydration alone as well as st and ard hydration for the protection of renal functions in patients with mild to moderate renal dysfunction who are undergoing coronary angiography and /or PCI . High-dose hydration without NAC was not better than st and ard hydration alone OBJECTIVES Prophylactic acetylcysteine along with hydration seems to be better than hydration alone in preventing the reduction in renal function induced by a contrast dye . BACKGROUND Contrast media can lead to acute renal failure that may occasionally require hemodialysis . METHODS One hundred eighty-three consecutive patients with impairment of renal function , undergoing coronary and /or peripheral angiography and /or angioplasty , were r and omly assigned to receive 0.45 % saline intravenously and acetylcysteine ( 600 mg orally twice daily ; group A , n = 92 ) or 0.45 % saline intravenously alone ( group B , n = 91 ) before and after nonionic , low-osmolality contrast dye administration . RESULTS The baseline serum creatinine concentrations were similar ( 1.5 + /- 0.4 mg/dl in group A vs. 1.5 + /- 0.4 mg/dl in group B ; p = 0.37 ) . An increase of > or = 25 % in the baseline creatinine level 48 h after the procedure occurred in 6 ( 6.5 % ) of 92 patients in group A and in 10 ( 11 % ) of 91 patients in group B ( p = 0.22 ) . In the subgroup with a low ( < 140 ml ) contrast dose , renal function deterioration occurred in 5 ( 8.5 % ) of 60 patients in group B and in 0 of 60 patients in group A ( p = 0.02 ; odds ratio [ OR ] 0.44 , 95 % confidence interval [ CI ] 0.35 to 0.54 ) . In the subgroup with a high contrast dose , no difference was found ( 5/31 vs. 6/32 patients , p = 0.78 ) . By multivariate analysis , the amount of contrast agent , but not the treatment strategy , was a predictor of the occurrence of contrast dye-associated nephrotoxicity ( OR 2.58 , 95 % CI 1.1 to 4.9 ; p = 0.035 ) . CONCLUSIONS In patients with reduced renal function undergoing angiography and /or angioplasty , the amount of contrast agent , but not the administration of prophylactic acetylcysteine , was a predictor of renal function deterioration .  Prophylactic acetylcysteine might provide better protection than hydration alone , only when a small volume of contrast agent is used BACKGROUND Contrast-induced nephropathy ( CIN ) after cardiac catheterization is common in patients with preexisting renal dysfunction . Studies of oral acetylcysteine to prevent CIN have produced conflicting results . Intravenous N-acetylcysteine ( NAC ) has logistic advantages in this setting . The objective of this study was to evaluate , in a blinded , r and omized , placebo-controlled fashion , whether intravenous NAC reduced CIN in the setting of cardiac catheterization in patients with preexisting renal insufficiency . METHODS Patients with renal dysfunction undergoing cardiac catheterization were r and omly assigned to intravenous NAC 500 mg immediately before the procedure or placebo . All patients received isotonic saline ( 200 mL ) beforeh and , followed by 1.5 mL/kg per hour for 6 hours , unless contraindicated . Exclusion criteria included acute renal failure , creatinine > 400 micromol/L , concurrent dialysis , unstable clinical status , and prior NAC use . Baseline creatinine was obtained immediately before the procedure and repeated 2 to 8 days later . The primary end point was the occurrence of CIN defined as a reduction in creatinine clearance from baseline of > 5 mL/min ( Cockcroft-Gault formula ) . RESULTS The study was terminated early because of a determination of futility by the Data Safety Monitoring Committee after enrollment of 487 patients . The median baseline creatinine clearance was 44 mL/min ( interquartile range , 33 , 55 ) . Median contrast received was 120 mL ( interquartile range , 80 , 175 ) . Baseline characteristics were similar in the two groups . Altogether , 98 ( 22.0 % ) subjects had the primary end point : 23.3 % in the NAC group and 20.7 % in the placebo arm ( P = .57 ) . CONCLUSIONS In this large , r and omized trial , enrolling a high-risk group of patients with impaired renal function , intravenous NAC was ineffective in preventing CIN OBJECTIVES The aim of this r and omized , single-blind , controlled trial was to assess N-acetylcysteine effects on contrast-induced nephropathy and reperfusion injury in ST-segment elevation myocardial infa rct ion patients undergoing primary angioplasty with moderate contrast volumes . BACKGROUND High-dose N-acetylcysteine reduced the incidence of contrast-induced nephropathy in patients with high contrast volumes and reduced reperfusion injury in animal trials . METHODS Patients undergoing primary angioplasty were r and omized to either high-dose N-acetylcysteine ( 2 x 1,200 mg/day for 48 h ; n = 126 ) or placebo plus optimal hydration ( n = 125 ) . The 2 primary end points were : 1 ) the occurrence of > 25 % increase in serum creatinine level < 72 h after r and omization ; and 2 ) a reduction in reperfusion injury measured as myocardial salvage index by magnetic resonance imaging . RESULTS The median volume of an iso-osmolar contrast agent during angiography was 180 ml ( interquartile range [ IQR ] 140 to 230 ml ) in the N-acetylcysteine and 160 ml ( IQR 120 to 220 ml ) in the placebo group ( p = 0.20 ) . The primary end point contrast-induced nephropathy occurred in 14 % of the N-acetylcysteine group and in 20 % of the placebo group ( p = 0.28 ) . The myocardial salvage index was also not different between both treatment groups ( 43.5 ; IQR 25.4 to 71.9 vs. 51.5 ; IQR 29.5 to 75.3 ; p = 0.36 ) . Activated oxygen protein products and oxidized low-density lipoprotein as markers for oxidative stress were reduced by as much as 20 % in the N-acetylcysteine group ( p < 0.05 ) , whereas no change was evident in the placebo group . CONCLUSIONS High-dose intravenous N-acetylcysteine reduces oxidative stress . However , it does not provide an additional clinical benefit to placebo with respect to CIN and myocardial reperfusion injury in nonselected patients undergoing angioplasty with moderate doses of contrast medium and optimal hydration . ( Myocardial Salvage and Contrast Dye Induced Nephropathy Reduction by N-Acetylcysteine [ LIPSIA-N-ACC ] ; NCT00463749 ) CONTEXT The antioxidant acetylcysteine prevents acute contrast nephrotoxicity in patients with impaired renal function who undergo computed tomography scanning . However , its role in coronary angiography is unclear . OBJECTIVE To determine whether oral acetylcysteine prevents acute deterioration in renal function in patients with moderate renal insufficiency who undergo elective coronary angiography . DESIGN AND SETTING Prospect i ve , r and omized , double-blind , placebo-controlled trial conducted from May 2000 to December 2001 at the Grantham Hospital at the University of Hong Kong . PARTICIPANTS Two hundred Chinese patients aged mean ( SD ) 68 ( 6.5 ) years with stable moderate renal insufficiency ( creatinine clearance < 60 mL/min [ 1.00 mL/s ] ) who were undergoing elective coronary angiography with or without intervention . INTERVENTION Participants were r and omly assigned to receive oral acetylcysteine(600 mg twice per day ; n = 102 ) or matching placebo tablets ( n = 98 ) on the day before and the day of angiography . All patients received low-osmolality contrast agent . MAIN OUTCOME MEASURES Occurrence of more than a 25 % increase in serum creatinine level within 48 hours after contrast administration ; change in creatinine clearance and serum creatinine level . RESULTS Twelve control patients ( 12 % ) and 4 acetylcysteine patients ( 4 % ) developed a more than 25 % increase in serum creatinine level within 48 hours after contrast administration ( relative risk , 0.32 ; 95 % confidence interval [ CI ] , 0.10 - 0.96 ; P = .03 ) . Serum creatinine was lower in the acetylcysteine group ( 1.22 mg/dL [ 107.8 micromol/L ] ; 95 % CI , 1.11 - 1.33 mg/dL vs 1.38 mg/dL [ 122.9 micromol/L ] ; 95 % CI , 1.27 - 1.49 mg/dL ; P = .006 ) during the first 48 hours after angiography . Acetylcysteine treatment significantly increased creatinine clearance from 44.8 mL/min ( 0.75 mL/s ) ( 95 % CI , 42.7 - 47.6 mL/min ) to 58.9 mL/min ( 
    Output:
    
The results of the present paper support the use of NAC in the prevention of CIN  in patients undergoing CAG±PCI .