Optimalization of Nephroprotection Using N-Acetylcysteine

Inclusion Criteria: * Chronic kidney disease * Stable proteinuria above 300 mg/24 hours (no variations above 25% in the last 6 months) * Normal or slightly impaired stable renal function defined as serum creatinine level below 1.7 mg/dl (eGFR \> 45 ml/min) Exclusion Criteria: * Nephrotic syndrome * Steroids or other immunosuppressive treatment minimum during six months before the study * Diabetes mellitus * Potassium serum level \> 5.1 mEq/L * Albumin serum level \< 2.0mg/dL * Creatinine serum level \>2 mg/dl * Current diagnosis of heart failure New York Heart Association (NYHA) Class II-IV * Clinically significant valvular heart disease or second or third degree heart block without a pacemaker * History of hypertensive encephalopathy, cerebrovascular accident or transient ischemic cerebral attack * History of myocardial infarction, unstable angina pectoris, coronary bypass surgery, or any percutaneous coronary intervention * History of malignancy including leukemia and lymphoma (but not basal cell skin carcinoma) within the past five years * Pregnant or nursing women * Any surgical or medical condition which might significantly alter the absorption, distribution, metabolism, or excretion of study drugs. * History of alcohol abuse * NSAID abuse (more than 2 doses per week) * Known or suspected contraindications to the study medications, including history of allergy to ACE inhibitors, AT-1 receptor blockers and N-acetylcysteine