The effect of HN-65021 on responses to angiotensin II in human forearm vasculature

We studied the effect of (2-butyl-4-chloro-1[[2'-(1H-tetrazol-5-yl) [1,1'-biphenyl]methyl]-1H-imadazole-5-carboxylic acid,-1-(ethoxycarbonyloxy) ethyl-ester (HN-65021), on angiotensin II induced vasoconstriction in forearm vasculature of eight healthy men. Placebo and HN-65021 (5, 10 and 100 mg) were administered orally. Forearm blood flow was measured by venous occlusion plethysmography during rising dose brachial artery infusions of angiotensin II (0.3-1000 pmol min-1) 2 h after dosing. HN-65021 inhibited angiotensin II, causing a shift to the right of the dose-response curve. Angiotensin II (100 pmol min-1) decreased mean blood flow in the infused arm by 63.1 +/- 3.2% when infused following placebo and by 49.9 +/- 4.3%, 50.7 +/- 3.5% and 36.4 +/- 2.8% following HN-65021 doses of 5.10 and 100 mg respectively. These results demonstrate that HN-65021 antagonises angiotensin II receptor mediated vasoconstriction in human forearm resistance vessels.

Magnesium deficiency may be an important determinant of ventricular ectopy in digitalised patients with chronic atrial fibrillation

Digitalised patients with chronic atrial fibrillation (AF) have a high prevalence of ventricular premature beats (VPB); magnesium deficiency may be a contributory factor. We have used a magnesium loading-test to examine the relationship between ventricular ectopy and magnesium status in 14 digitalised patients with chronic AF. Among seven patients with infrequent VPB (less than 250 24 h-1; mean 107 24 h-1) mean magnesium retention was 10.1% and four subjects retained no significant quantities of magnesium, indicating magnesium repletion. Among the remaining seven patients, mean magnesium retention was significantly higher (33.1%, P less than 0.02) and all patients retained 20% or more of the load given. There was an overall relationship between Mg retention and numbers of VPB (rs = 0.54; P less than 0.05). Magnesium deficiency may be determinant of ventricular ectopy in digitalised patients with chronic AF.

A pharmacokinetic study of cilazapril in elderly and young volunteers

1. Cilazaprilat is an inhibitor of angiotensin converting enzyme (ACE) and is the active metabolite of cilazapril. The pharmacokinetics of cilazaprilat, and the inhibition of plasma ACE were investigated in 12 elderly and 12 young healthy volunteers. 2. Single oral 1 mg doses of cilazapril were given to the elderly (age range 65-83 years) and the young (age range 18-31 years) in an open study. Plasma and urinary cilazaprilat concentrations, and plasma ACE activities were measured up to 72 h after dosing by radioenzymatic methods. 3. Cilazapril was well tolerated in both young and elderly subjects. Small falls in blood pressure were observed up to 8-24 h after dosing. 4. The mean peak plasma cilazaprilat concentration in the elderly (11.5 ng ml-1) was significantly greater (P less than 0.02) than the corresponding value in the young (8.3 ng ml-1). Total and renal clearances were significantly lower (both P less than 0.05) in the elderly (12.8 and 5.11 h-1) than in the young (16.0 and 7.21 h-1). Total urinary recovery of cilazaprilat was similar for the two groups at about 43% of dose. 5. Plasma ACE inhibition was slightly greater in the elderly but the mean inhibition in the two groups did not differ by more than 10% at any time-point from 1-72 h. 6. The plasma concentrations of cilazaprilat required for 90% ACE inhibition were similar at 4.7 and 4.8 ng ml-1 in the elderly and young respectively. 7. It is concluded that the age-related changes in cilazaprilat kinetics and in the degree of ACE inhibition are small.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacokinetics and bioavailability of cilazapril in normal man

1. The pharmacokinetics of cilazapril and its active metabolite, cilazaprilat, were investigated in a three-part crossover study in 12 healthy male volunteers aged 19-38 years, excluding one subject who withdrew from the study. 2. Single 2.5 mg oral doses of cilazapril, and equivalent oral and intravenous doses of cilazaprilat were administered as aqueous solutions to the fasted subjects. There was an interval of 1 week between treatments. Concentrations of cilazapril and cilazaprilat in plasma and urine, and activities of angiotensin converting enzyme (ACE) in plasma were measured by radioenzymatic methods. 3. After 10 min infusion of cilazaprilat, the mean plasma concentration was 194 ng ml-1, and ACE inhibition was almost 100%. The decline in concentrations was polyphasic, with mean half-lives for the periods 1-4 h and 24-168 h of 0.90 and 46 h, respectively. Between 4 and 24 h the decline was non-linear, and ACE inhibition decreased from 91% to 67%. Urinary recovery of cilazaprilat averaged 91% of dose. 4. After oral cilazapril, the parent drug was rapidly absorbed and rapidly eliminated, with a mean maximum plasma concentration of 82 ng ml-1 at 0.83 h and a single elimination half-life of 1.3 h. Cilazaprilat peaked at 36 ng ml-1 about 1.7 h after dosing and the decline in concentrations was biphasic, with half-lives of 1.8 h and 45 h. After oral cilazaprilat, plasma concentrations were considerably lower, and the peak later (2.2 h). 5. Urinary recovery data indicated an absolute bioavailability for cilazaprilat of 57% (range 45-75%) from oral cilazapril, but only 19% (range 8-40%) from oral cilazaprilat.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in morning hyperglycaemia with basal human ultratard and prandial human actrapid insulin--a comparison of multiple injection regimens

Three 'pen'-administered multiple injection regimens have been compared with twice daily insulin injection regimens by means of 24-h profiles of plasma glucose and free insulin concentrations. Ten Type 1 diabetic patients received their usual twice daily insulin regimen and were then randomized to receive the same total daily insulin dose in four divided doses using (1) 50:50 premixed soluble and isophane, (2) 30:70 premixed soluble and isophane, and (3) preprandial soluble and evening crystalline-zinc insulins. Profiles were performed after 1 week on each regimen. Plasma glucose concentrations were similar during the twice daily regimen and the two premixed regimens, rising during the early hours of the morning to a peak between 0900 and 0930 h of 13.8 +/- 2.8 (+/- SD) mmol l-1 on the twice daily regimen, 13.6 +/- 5.3 mmol l-1 on the premixed 50:50 regimen, and 13.5 +/- 4.2 mmol-1 on the premixed 30:70 regimen. With the basal and prandial regimen, overnight plasma glucose concentrations were higher than with the other regimens between 2400 and 0300 h (p less than 0.05). Concentrations then fell until breakfast, and rose after this meal to a peak of 9.5 +/- 4.3 mmol l-1 (p less than 0.01). Mean plasma glucose concentrations were significantly lower than on the other three regimens between 0830 and 1100 h (p less than 0.05). Less variability was observed in 24-h mean plasma glucose concentrations during the basal and prandial regimen than during the other three regimens.