It is commonly assumed that thiazide diuretics are ineffective in patients with advanced renal failure (GFR < 30 ml/min/1.73 m2). Thiazides act on the nephron segment distal to the ascending thick loop of Henle, that is, the site of action of loop diuretics. Blockade of sodium reabsorption in the thiazide-sensitive segment should therefore obliterate the compensatory increase in sodium reabsorption seen after administration of loop diuretics and thus potentiate the natriuretic efficacy of loop diuretics even in advanced renal failure. In a single-blind, randomized, placebo controlled crossover study we compared the natriuretic and chloruretic effect of the loop diuretic, torasemide, given alone or in combination with the thiazide diuretic, butizid, in 10 patients with advanced renal failure (mean CIn 13.1 +/- 5.9 ml/min/1.73 m2). For two weeks patients adhered to a diet containing a standardized amount of Na+ and K+. On the 6th and 13th study days, two sham infusions were given to patients in order to assess basal 24-hour urinary electrolyte excretion. On the 7th and 14th days they were randomly allocated to receive either 50 mg i.v. torasemide in combination with a sham infusion or torasemide in combination with 20 mg i.v. butizid. Administration of torasemide alone significantly (P < 0.01) increased mean cumulative 24-hour excretion of sodium (from 154 +/- 30 to 232 +/- 59 mmol/24 hr) and chloride (from 128 +/- 21 to 233 +/- 84 mmol/24 hr) as compared with baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

The cardiovascular effects and pharmacokinetics of once-daily enalapril were studied after single-dose and subchronic treatment in eight patients with hypertension by use of ambulatory blood pressure monitoring. Enalapril, 10 mg, was given at either 7 AM or 7 PM in a randomized crossover design. In addition, inhibition of serum converting enzyme was studied. Subchronic treatment at 7 AM significantly reduced blood pressure during the day but was less effective at night. Subchronic dosing at 7 PM significantly further decreased nighttime blood pressure followed by a slow increase during the day, with no effect on elevated afternoon values. Peak concentrations of enalaprilat were found 3.5 hours (morning) and 5.6 hours (evening) after drug intake (p < 0.05), whereas peak effects occurred 7.4 hours (morning) and 12 hours (evening) after drug administration. In conclusion, 24-hour blood pressure profiles in patients with hypertension were significantly influenced by the time of enalapril dosing. Differences in effect profiles could not be attributed to similar changes in pharmacokinetics or to different time courses of angiotensin converting enzyme inhibition.

To prevent drug accumulation and adverse effects the dose of hydrophilic angiotensin-converting enzyme (ACE) inhibitors, e.g. lisinopril, must be reduced in patients with renal failure. To obtain a rational basis for dose recommendations, we undertook a prospective clinical trial. After 15 days of lisinopril treatment pharmacokinetic and pharmacodynamic parameters were determined in patients with advanced renal failure (n = 8; endogenous creatinine clearance [CLCR]: 18 ml.min-1.1.73 m-2) and in healthy subjects with normal renal function (n = 16; CLCR: 107 ml.min-1.1.73 m-2). The volunteers received 10 mg lisinopril once daily, the daily dose in patients (1.1-2.2 mg) was adjusted to the individual CLCR according to the method of Dettli [13]. After 15 days of lisinopril treatment the mean maximal serum concentration (Cmax) in patients was lower than in volunteers (30.7 vs 40.7 ng.ml-1, while the mean area under the concentration-time curve (AUC0-24 h) was higher (525 vs 473 ng.h-1.ml-1). ACE activity on day 15 was almost completely inhibited in both groups. Plasma renin activity, angiotensin I and angiotensin II levels documented marked inhibition of converting enzyme in volunteers and patients. Furthermore, average mean arterial blood pressure in patients decreased by 5 mmHg and proteinuria from 3.9-2.7 g per 24 h after 15 days of treatment with the reduced dose of lisinopril. Adjustment of the dose of lisinopril prevents significant accumulation of the drug in patients with advanced renal failure during chronic therapy. Mean serum levels did not exceed this in subjects with normal renal function receiving a standard dose.(ABSTRACT TRUNCATED AT 250 WORDS)