enalaprilat-anhydrous and Kidney-Failure--Chronic

Enalapril maleate is a prodrug which when administered orally is hydrolysed to release the active converting enzyme inhibitor enalaprilat. Enalapril maleate is 60% absorbed and 40% bioavailable as enalaprilat. Both compounds undergo renal excretion without further metabolism. The functional half-life for accumulation of enalaprilat is 11 h, and this is increased in the presence of a reduction in renal function. Inhibition of converting enzyme inhibition is associated with reductions in plasma angiotensin II and plasma aldosterone, and with increases in plasma renin activity and plasma angiotensin I. Acute and chronic effects have been reviewed. When given with hydrochlorothiazide, enalapril attenuates the secondary aldosteronism and ameliorates the hypokalaemia from diuretics. Both acutely and chronically in patients with essential hypertension, enalapril reduced blood pressure with a rather flat dose-response curve. No evidence of a triphasic response such as seen with captopril has been demonstrated with enalapril, and blood pressure returns smoothly to pretreatment levels when the drug is abruptly discontinued. Once- or twice-daily dosing gives similar results. The antihypertensive effects of enalapril are potentiated by hydrochlorothiazide. Haemodynamically, blood pressure reduction is associated with a reduced peripheral vascular resistance and an increase in cardiac output and stroke volume with little change in heart rate. Renal vascular resistance decreases, and renal blood flow may increase without an increase in glomerular filtration in patients with normal renal function. In patients with essential hypertension and glomerular filtration rates below 80 ml/min/m2, both renal blood flow and glomerular filtration rates may increase.

Topics: Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Bradykinin; Dipeptides; Drug Administration Schedule; Enalapril; Enalaprilat; Heart Failure; Heart Rate; Humans; Hydrochlorothiazide; Hypertension; Kidney; Kidney Failure, Chronic; Norepinephrine; Prostaglandins; Renal Circulation; Renin

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.. 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.. 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).. 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.

Topics: Adult; Aged; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Dose-Response Relationship, Drug; Enalapril; Enalaprilat; Female; Glomerular Filtration Rate; Humans; Hypertension; Kidney Failure, Chronic; Male; Metabolic Clearance Rate; Middle Aged

Most angiotensin-converting enzyme (ACE) inhibitors and their metabolites are excreted renally and doses should hence be reduced in renal insufficiency. We studied whether the dosage of enalapril in daily clinical practice is associated with drug accumulation of enalaprilat in chronic renal failure.. Fifty nine out-patients with plasma creatinine >150 micromol/L and chronic antihypertensive treatment with enalapril were investigated, in a cross-sectional design.. Median glomerular filtration rate (GFR) was 23(range 6-60) ml/minute/1.73 m2. The daily dose of enalapril was 10 (2.5-20) mg and the trough serum concentration of enalaprilat was 31.8 (<2.5-584.7)ng/ml. Ninety percent of the patients had higher serum concentrations of enalaprilat than has been reported in subjects with normal kidney function, and a marked elevation of serum enalaprilat was observed in patients with GFR <30 ml/minute. All but three patients had serum ACE activity below the reference range. The ACE genotype did not influence the results. Additional pharmacokinetic studies were done in nine patients in whom GFR was 23 (10-42)ml/minute/1.73 m2. The median clearance of enalaprilat was 28 (16-68) ml/minute and correlated linearly with GFR (r=0.86, p=0.003). Intra-subject day-to-day variation in trough concentrations was 19.7%.. Patients with chronic renal failure given small or moderately high doses of enalapril may thus have markedly elevated levels of serum enalaprilat. Whether this affords extra renoprotection, or on the contrary may inappropriately impair renal function, is not known, and should be investigated in prospective, controlled studies.

Topics: Adult; Aged; Angiotensin-Converting Enzyme Inhibitors; Cross-Sectional Studies; Enalapril; Enalaprilat; Female; Genotype; Glomerular Filtration Rate; Humans; Hypertension, Renal; Kidney Failure, Chronic; Male; Middle Aged; Peptidyl-Dipeptidase A; Polymorphism, Genetic

To compare the serum pharmacokinetics of fosinoprilat with enalaprilat and lisinopril after 1 and 10 days of dosing with fosinopril, enalapril and lisinopril.. Patients with congestive heart failure (CHF, NYHA Class II-IV) and chronic renal insufficiency (creatinine clearance

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Angiotensin-Converting Enzyme Inhibitors; Blood Pressure; Enalaprilat; Female; Fosinopril; Heart Failure; Humans; Kidney Failure, Chronic; Lisinopril; Male; Middle Aged; Peptidyl-Dipeptidase A; Time Factors

The pattern of binding of monoclonal antibodies (mAbs) to 16 epitopes on human angiotensin I-converting enzyme (ACE) comprise a conformational ACE fingerprint and is a sensitive marker of subtle protein conformational changes.. Toxic substances in the blood of patients with uremia due to End Stage Renal Disease (ESRD) can induce local conformational changes in the ACE protein globule and alter the efficacy of ACE inhibitors.. The recognition of ACE by 16 mAbs to the epitopes on the N and C domains of ACE was estimated using an immune-capture enzymatic plate precipitation assay. The precipitation pattern of blood ACE by a set of mAbs was substantially influenced by the presence of ACE inhibitors with the most dramatic local conformational change noted in the N-domain region recognized by mAb 1G12. The "short" ACE inhibitor enalaprilat (tripeptide analog) and "long" inhibitor teprotide (nonapeptide) produced strikingly different mAb 1G12 binding with enalaprilat strongly increasing mAb 1G12 binding and teprotide decreasing binding. Reduction in S-S bonds via glutathione and dithiothreitol treatment increased 1G12 binding to blood ACE in a manner comparable to enalaprilat. Some patients with uremia due to ESRD exhibited significantly increased mAb 1G12 binding to blood ACE and increased ACE activity towards angiotensin I accompanied by reduced ACE inhibition by inhibitory mAbs and ACE inhibitors.. The estimation of relative mAb 1G12 binding to blood ACE detects a subpopulation of ESRD patients with conformationally changed ACE, which activity is less suppressible by ACE inhibitors. This parameter may potentially serve as a biomarker for those patients who may need higher concentrations of ACE inhibitors upon anti-hypertensive therapy.

Topics: Angiotensin-Converting Enzyme Inhibitors; Antibodies, Monoclonal; Biomarkers; Enalaprilat; Epitopes; Humans; Immunoprecipitation; Kidney Failure, Chronic; Models, Molecular; Peptidyl-Dipeptidase A; Protein Binding; Protein Conformation; Teprotide; Uremia

1. Lisinopril and enalapril were administered as 2.5 mg single doses and as eight single daily 2.5 mg doses to separate groups of six patients with chronic renal failure. Patients were receiving regular haemodialysis. 2. In the absence of haemodialysis, the decline in plasma concentrations of lisinopril and enalaprilat was extremely slow and plasma concentrations were generally high. 3. Haemodialysis had large effects on plasma concentrations of lisinopril and enalaprilat. A 4 h period reduced plasma concentrations of both drugs by around one-half and often by significantly more than this. Even 1 or 2 h of haemodialysis had significant effects. 4. Haemodialysis plasma clearance was similar for both drugs with mean values of the order of 40 ml min-1. Clearance did not markedly differ when measured after 1, 2 or 4 h of haemodialysis or after single or multiple doses of lisinopril or enalapril. 5. The design of dosage regimens of both lisinopril and enalapril for patients with severe renal impairment or chronic renal failure should take into consideration the use and effects of haemodialysis.

Topics: Adult; Angiotensin-Converting Enzyme Inhibitors; Creatinine; Enalapril; Enalaprilat; Female; Humans; Kidney Failure, Chronic; Lisinopril; Male; Middle Aged; Renal Dialysis