There are many controversies about the role of N-Acetyl Cystein in preventing of contrast
nephropathy. These contradictory results may be due to different criteria for patients'
selection, different end points, different type and dose of N-Acetyl Cystein administration
and finally different prophylactic measures other than N-Acetyl Cystein. The investigators
try to enroll a double blind double dummy study with a good power to compare the effect of
this drug both in the form of oral and intravenous against the placebo in preventing the
contrast nephropathy in the patients whom undergo coronary angiography/angioplasty.