title: Enalapril dosage in progressive chronic nephropathy: a randomised, controlled trial.
abstract: OBJECTIVE
  In chronic renal failure, clearance of enalapril is reduced. Hence, a renoprotective effect may be achieved with lower doses than conventionally used. Since marked inter-patient variation in concentrations of enalaprilat has been shown in patients with renal failure despite equivalent dosage of enalapril, a direct comparison of the effect of high versus low plasma concentrations of enalaprilat on the progression of renal failure was undertaken.
  
  
  METHODS
  Forty patients with a median glomerular filtration rate (GFR) of 17 (6-35) ml/min/1.73 m2 were studied in an open-label, randomised trial comparing patients with a high (>50 ng/ml) with patients with a low (<10 ng/ml) target trough plasma concentration of enalaprilat. The dose of enalapril was titrated accordingly. The patients were followed for 12 months or until they needed renal replacement therapy. GFR was measured at 3-month intervals by the plasma clearance of 51Cr-EDTA, and the individual rates of progression of renal failure were calculated as the slope of GFR versus time plot.
  
  
  RESULTS
  In the high-concentration group, the median enalaprilat trough concentration was 92.9 ng/ml (21.8-371.0 ng/ml) and in the low-concentration group it was 9.1 ng/ml (2.5-74.8 ng/ml) at 3 months follow-up (P<0.001). The median daily doses of enalapril were 10 mg (2.5-30 mg) and 1.88 mg (1.25-5 mg) in the high and low groups, respectively (P<0.001). In the high-concentration group, the mean+/-SE decline in renal function was 6.1+/-1.5 ml/min/1.73 m2 per year and in the low-concentration group it was 4.3+/-14.4 ml/min/1.73 m2 per year (P=0.48). Five patients in the high-concentration group reached end-stage renal failure whereas none in the low-concentration group did (P=0.04). There were no statistically significant differences in blood pressure level, concomitant antihypertensive therapy or urinary albumin excretion. However, the high-enalaprilat concentration group had an overall higher plasma potassium concentration of 0.42 mmol/l than the low group (P<0.001).
  
  
  CONCLUSIONS
  In patients with moderate to severe renal insufficiency, a low concentration of enalaprilat afforded the same degree of renoprotection, blood pressure control and minimisation of proteinuria as a high concentration, during 12 months of follow-up. The high-dosage treatment was associated with a more pronounced tendency to hyperkalaemia. Thus, there seems to be no indication for increasing the daily dose of enalapril beyond what achieves adequate blood pressure control in this group of patients.
authors.affiliation: Department of Nephrology, Herlev Hospital, University of Copenhagen, Denmark. thomaselungjensen@hotmail.com
authors.forename: Thomas
authors.initials: T
authors.lastname: Elung-Jensen
authors.forename: Jens
authors.initials: J
authors.lastname: Heisterberg
authors.forename: Jesper
authors.initials: J
authors.lastname: Sonne
authors.forename: Svend
authors.initials: S
authors.lastname: Strandgaard
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Kamper
mesh_terms: D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004656:Enalapril / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D015773:Enalaprilat / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D004656:Enalapril; D015773:Enalaprilat