title: The impact of lipoic acid on endothelial function and proteinuria in quinapril-treated diabetic patients with stage I hypertension: results from the QUALITY study.
abstract: BACKGROUND
  We sought to determine whether a combination of angiotensin-converting enzyme inhibitors (ACEIs) and the nutraceutical α-lipoic acid (ALA) regulates blood pressure, endothelial function, and proteinuria in diabetic patients with Stage I hypertension.
  
  
  METHODS
  A total of 40 diabetic patients with Stage I hypertension were treated in a crossover double-blinded manner. Patients were administered quinapril ([QUI] 40 mg/d) for 8 weeks or QUI + ALA (600 mg/d) for 8 weeks. Measurements included blood pressure, 24-hour collection of urinary albumin, and endothelial-dependent flow-mediated dilation (FMD).
  
  
  RESULTS
  There was a change of metabolic parameters in both study groups after 8 weeks of therapy. In comparison to baseline, the 24-hour urinary albumin significantly decreased by 30% in the QUI group (P = .018, time comparison) and 53% in QUI + ALA group (P < .005, time and group comparison). Also, when compared with baseline, FMD significantly increased by 58% in QUI group (P < .005, time comparison) and by 116% in QUI + ALA group (P < .005, time and group comparison). Systolic and diastolic blood pressure reduced significantly by 10% with QUI treatment. There was no further blood pressure reduction when patients were administered both QUI and ALA.
  
  
  CONCLUSIONS
  In diabetic patients with hypertension, QUI reduces blood pressure, proteinuria, and improves endothelial function. Moreover, this effect is strongly potentiated with a combination of QUI and ALA. These results may attenuate the progression of vascular pathophysiology seen in patients with a combination of diabetes and hypertension.
authors.affiliation: Emory University School of Medicine, Division of Cardiology, Atlanta, GA, USA.
authors.forename: Syed T
authors.initials: ST
authors.lastname: Rahman
authors.forename: Nadya
authors.initials: N
authors.lastname: Merchant
authors.forename: Tahir
authors.initials: T
authors.lastname: Haque
authors.forename: Jessica
authors.initials: J
authors.lastname: Wahi
authors.forename: Sujan
authors.initials: S
authors.lastname: Bhaheetharan
authors.forename: Keith C
authors.initials: KC
authors.lastname: Ferdinand
authors.forename: Bobby V
authors.initials: BV
authors.lastname: Khan
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000188:drug therapy / Q000209:etiology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000188:drug therapy / Q000209:etiology; D000077583:Quinapril; D044005:Tetrahydroisoquinolines / Q000008:administration & dosage / Q000627:therapeutic use*; D008063:Thioctic Acid / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D044005:Tetrahydroisoquinolines; D008063:Thioctic Acid; D000077583:Quinapril