High serum enalaprilat in chronic renal failure

Are ACEI/ARBs associated with the decreased peritoneal protein clearance in long-term PD patients?

Objective. Peritoneal protein clearance (PrC) is recognized as a new marker of systemic endothelial dysfunction and predictor of mortality in patients on peritoneal dialysis (PD). Given that angiotensin-converting enzyme inhibitors (ACEI)/angiotensin II receptor blockers (ARBs) could improve endothelial dysfunction in the general population, we aim to explore whether this benefit is present in the PD population.

METHODS

We analysed data from a PD cohort with data prospectively collected. The PrC, defined daily doses (DDDs) of ACEI/ARBs, as well as other clinical variables were recorded at baseline and then repeatedly measured at 3- to 6-month intervals till to death or censoring. A total of 156 patients were treated with ACEI/ARBs with 0.60 of median time-averaged DDDs, the untreated group consisted of 149 patients who received none of the above drugs during the follow-up.

RESULTS

The baseline and time-averaged PrC were 69.9 ± 34.7 mL/day and 75.2 ± 28.3 mL/day, respectively. Time-averaged PrC was an independent predictor of mortality adjusted for recognized confounders in a multivariate Cox regression model (P = 0.037). There were no significant differences in the time course of PrC (P = 0.82) and peritoneal protein loss (P = 0.83) between the ACEI/ARBs group and the untreated group after adjustment for age, gender, diabetes, baseline C-reactive protein, mean blood pressure and baseline PrC or baseline peritoneal protein loss in the generalized linear mixed model.

CONCLUSIONS

We conclude that ACEI/ARBs did not correlate with a decreased PrC in this observational study. The effect of higher doses of ACEI/ARBs needs to be determined in future interventional studys.

Feasibility of combined treatment with enalapril and candesartan in advanced chronic kidney disease

BACKGROUND

Dual blockade of the renin-angiotensin system (RAS) has been claimed to have a specific renal protective effect in chronic kidney disease (CKD). The present short-term study reports on the feasibility of dual blockade in a consecutive group of patients with CKD stage 3-5.

METHODS

Forty-seven CKD patients, mean age 59 years, with mean estimated glomerular filtration rate (GFR) 26 ml/min/1.73 m(2) (range 13-49) and blood pressure (BP) 133/78 mmHg, were block randomized in an open study to 16 weeks of monotherapy with increasing doses of RAS blockade aiming at enalapril 20 mg o.d. or candesartan 16 mg o.d. Thereafter, the complementary drug was added in incremental doses over a period of 5 weeks aiming at combined enalapril 20 mg and candesartan 16 mg for 3 weeks. Seventy-five percent of the patients were known to be RAS blockade tolerant. Blood samples and BP were measured every 2-3 weeks. Doses of study medication were reduced in case of hyperkalemia >5.5 mmol/l, a sustained rise in p-creatinine >30% or symptomatic hypotension.

RESULTS

Twenty-one patients (45%) did not tolerate dual blockade in aimed dosages due to unacceptable p-creatinine increase (n = 12, including two study withdrawals), hypotension (n = 6), general discomfort (n = 2) or unmanageable hyperkalemia (n = 1). Hyperkalemia >5.5 mmol/l was seen in seven patients (15%). The reduced-dose group had baseline lower eGFR and diastolic BP.

CONCLUSIONS

Forty-five percent of CKD stage 3-5 patients did not tolerate dual RAS blockade with 20 mg enalapril and 16 mg candesartan daily, primarily due to loss of renal function or hypotension. Hyperkalemia could be managed in most patients. Caution is recommended when giving this treatment to patients with advanced CKD.

Enalapril dosage in progressive chronic nephropathy: a randomised, controlled trial

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).

CONCLUSION

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.

Blood pressure response to conventional and low-dose enalapril in chronic renal failure

AIMS

In chronic renal failure, the clearance of most ACE inhibitors including enalapril is reduced. Hence, with conventional dosage, plasma enalaprilat may be markedly elevated. It is unclear whether this excess of drug exposure affords an improved control of blood pressure. The aim of the present study was to evaluate short-term blood pressure response to two different plasma levels of enalaprilat.

METHODS

As part of an open, randomized, controlled trial of the effect of high and low dosage of enalapril on the progression of renal failure, short-term blood pressure response was evaluated. Data were analysed in all patients completing 3 months of follow-up. The patients were allocated to two trough plasma concentrations of enalaprilat, either above 50 ng ml(-1) (high) (n = 17) or below 10 ng ml(-1) (low) (n = 18), and the daily dose of enalapril titrated accordingly.

RESULTS

Median (range) glomerular filtration rate (GFR) at baseline was 18 (7.9) in the high enalaprilat concentration group and 17 (7.3) ml min(-1) 1.73 m(2) in the low concentration group (NS). Nine patients in each group were on treatment with enalapril at baseline with a median daily dose of 5 mg in both the high (5-10) and low (2.5-20) concentration group. At 3 months' follow-up, the dose was 10 (2.5-30) and 1.9 (1.25-5) mg (P < 0.0001), respectively. After 3 months median trough concentrations of enalaprilat were 82.5 (22-244) ng ml(-1) and 9.1 (2.5-74.8) ng ml(-1) (P < 0.002). At baseline the median systolic blood pressures in the two groups were 140 (110-200) and 133 (110-165), in the high and low enalaprilat concentration groups, respectively, and after 3 months they were 135 (105-170) and 130 (105-170) mmHg (NS). Median diastolic blood pressure was 80 mmHg in each group both at baseline (65-100) and at follow-up (60-95) (NS). There was no difference between the groups in concomitant antihypertensive treatment (number of patients treated, mean daily dose) during the observation period. Proteinuria remained stable during the study period in both groups; patients in the high concentration group had higher plasma potassium concentrations at day 90 and patients in the low group experienced a slight increase in GFR.

CONCLUSIONS

In moderate to severe chronic renal insufficiency the same degree of blood pressure control was achieved on low as well as moderate daily doses of enalapril. This was irrespective of concomitant antihypertensive treatment.