Effects of fosinopril on renal function, baroreflex response and noradrenaline pressor response in conscious normotensive dogs

The blood pressure. renal function, baroreflex response of heart rate and noradrenaline (norepinephrine) pressor response were determined in conscious, normotensive, sodium-replete dogs that had received fosinopril. Oral administration of fosinopril at a dose of 1 mg/kg per day for 5 days decreased the systolic arterial pressure from 147.1 +/- 3 to 131.8 +/- 4.3 mmHg (p < 0.05) and the mean arterial pressure from 99.7+/- 3.9 to 87.5 +/- 2.8 mmHg (p < 0.05), while heart rate was unchanged. A study of the noradrenaline pressor response showed a tendency to alleviate the increased MAP by fosinopril treatment, although this was not significant. There were no significant changes in the sensitivity of the baroreflex response in HR, although the setpoint was reduced. After 7 days of fosinopril treatment, the glomerular filtration rate had increased by 18.5% (p < 0.05). The effective renal plasma flow tended to increase, leaving the filtration fraction unchanged. The renal vascular resistance was reduced by 11.3% (p < 0.05). Fosinopril caused a significant 41.5% increase in urinary excretion of Na+ (p < 0.05), along with an elevation of urinary excretion of K+ and Cl- . It is concluded that fosinopril can lower the blood pressure, reduce the noradrenaline pressor response and lower the cardiac baroreflex setpoint to noradrenaline. Oral administration of fosinopril for 7 days affects both the renal haemodynamics and electrolyte excretions in conscious, normotensive, sodium-replete dogs.

Fosinopril: pharmacokinetics and pharmacodynamics in Chinese subjects

This study examined thepharmacokinetics and pharmacodynamics of fosinopril (IVand oral) in Chinese subjects to determine whether they were different from a group of somewhat heavier and older Western control subjects previously published using the same methods. It was an open-label, randomized, balanced, two-way crossover study comparing oral and IV pharmacokinetics in 12 healthy Chinese subjects in a clinic in Taiwan. Each subject received 10 mg of oral fosinopril or 7.5 mg of IV fosinoprilatin a randomized sequence with sampling for fosinoprilat concentrations over 48 hours. Standard pharmacokinetics, including AUC, Cmax Tmax, T 1/2, Vss, bioavailability, total clearance, and renal and nonrenal clearance, were determined as well as pharmacodynamic effects on angiotensin-converting enzyme (ACE) activity. Following oral administration of 10 mg fosinopril, AUC0-T and AUCinf were 1,556 +/- 586 ng x hr/mL and 1,636 +/- 620 ng x hr/mL, respectively; T 1/2 was 17.4 +/- 11.4 hr; Cmax was 183.4 +/- 59.4 ng/mL; and median Tmax was 4.0 hr, with > 99% protein binding. Following IV administration of 7.5 mg fosinoprilat, AUC0-T and AUCinf were 7,727 +/- 2,638 ng x hr/mL and 7,816 +/- 2,693 ng x hr/mL, respectively; T 1/2 was 13.0 +/- 5.2 hr; and median Tmax was 4.0 hr, with 99.5% +/- 0.22% protein binding and a Vss of 5,850 +/- 2,780 mL. Bioavailability was 22.3% +/- 7.9%. Percent urinary excretion was 7.6% +/- 2.6% after oral dosing and 42.6% +/- 6.1% after IV dosing. After IV, dosing total clearance was 1,088 +/- 439 mL/hr, renal clearance was 472 +/- 213 mL/hr, and nonrenal clearance was 617 +/- 246 mL/hr. ACE inhibition was essentially complete through 12 hours and markedly reduced through 24 hours. Compared to a somewhat heavier and older previously reported control group, pharmacokinetic values were similar except for a slightly lower AUC and total clearance in Chinese and a statistically significantly lower nonrenal clearance. Pharmacodynamic effects on ACE activity were essentially identical. There is no reason to expect significant differences in fosinopril dosing or effect in a Chinese population compared to a Western population.

Invasive pharmacodynamics of fosinopril in patients with congestive heart failure

Five patients with NYHA Class III CHF received 5 mg of fosinopril on each of 4 days. Hemodynamics were measured with a Swan-Ganz catheter after dosing on day 1. Measurements of plasma fosinoprilat, ACE activity, renin, and aldosterone were obtained. An Emax model was used to fit the effect-site concentration and mean arterial pressure change. A linear model was used to fit the effect-site concentration and the pulmonary artery wedge pressure (PAWP) change. At steady state on day 4, AUC0-24 was 1668 +/- 476 ng.hr/mL and Cmax was 143.5 +/- 33.6 ng/mL. The mean elimination half-life of fosinoprilat was 11.3 +/- 0.7 hours, and median Tmax occurred at 3 hours, corresponding to maximum plasma ACE inhibition. Plasma renin activity was unchanged, and mean plasma aldosterone level declined. Emax modeling using fosinoprilat concentrations and mean arterial pressure showed good prediction of the pharmacodynamic effects from the effect-site concentration. A linear relationship was observed between the effect-site concentrations of fosinoprilat and PAWP. When expressed in an Emax model, the pharmacodynamic actions of fosinopril in patients with CHF are a reflection of its pharmacokinetics.