Pharmacokinetics Of Ramipril Research Articles

Pharmacokinetics and pharmacodynamics of ramipril and ramiprilat in healthy cats

The pharmacokinetics of ramipril and its active metabolite, ramiprilat, was determined in cats following single and repeated oral doses of ramipril (Vasotop tablets) (once daily for 9 days) at dose rates of 0.125, 0.25, 0.5 and 1.0 mg/kg. The pharmacodynamic effects were assessed by measuring plasma angiotensin-converting enzyme (ACE) activity. Maximum ramipril concentrations were attained within 30 min following a single dose and declined rapidly (concentrations were below the limit of quantification 4 h after treatment). Peak ramiprilat concentrations were detected at approximately 1.5 h. The apparent terminal half-life (t((1/2)beta)) was > or =20 h irrespective of the dose. Ramiprilat accumulated in plasma (ratio of accumulation 1.3 to 1.9 depending on the dose rate) following repeated administration. Steady-state conditions were attained after the second dose. Excretion was predominant in faeces (87%) and to a lesser extent in urine (11%). The rate and extent of absorption of ramipril as well as its conversion to ramiprilat were not significantly influenced by the presence of food in the gastrointestinal tract. Plasma-ACE activity was almost completely abolished 0.5-2.0 h after treatment, irrespective of the dose rate. Significant inhibition of ACE activity of 54.7 to 82.6% (depending on the dosage) was still present 24 h after treatment. Treatment was well-tolerated in all cats. Ramipril at a dose rate of 0.125 mg/kg once daily produces significant and long-lasting inhibition of ACE activity in healthy cats. The appropriateness of this dosage regime needs to be confirmed in diseased cats.

Pharmacokinetics of ramipril in patients undergoing haemodialysis

Pharmacokinetics of ramipril in patients undergoing haemodialysis

Multiple-Dose Pharmacokinetics of Ramipril in Patients with Chronic Congestive Heart Failure

Thirteen patients with chronic congestive heart failure of NYHA class II-III received multiple doses (14 days) of ramipril (5 mg once daily); the concentrations of ramipril and ramiprilat in plasma, as well as ramipril, ramiprilat, glucuronides, diketopiperazine, and diketopiperazine acid in urine were measured at various times for 14 days. One patient dropped out after the first day due to hypotension and another who accidentally received another ACE inhibitor additionally was excluded, so that 11 patients completed the study. Ramipril and ramiprilat in plasma were determined by radioimmunoassay, and ramipril and its metabolites in urine were measured by gas chromatography in the laboratories of Hoechst AG. Peak concentrations of the active substance ramiprilat were reached after about 4 h and amounted to 22.3 +/- 11.1 ng/ml after the first dose, and a peak concentration of 26.6 +/- 10.0 ng/ml was observed 2.5 +/- 1.4 h on average after administration on day 14. Practically no accumulation was observed for ramiprilat; the AUD (0-24 h) values increased from 191.3 +/- 83.1 ng.h/ml for the first study day to 238.3 +/- 98.0 ng.h/ml for day 14. As expected, only very small fractions of the dose were excreted with urine as unchanged ramipril and ramipril glucuronide. Ramiprilat is excreted with urine to a larger extent than is rampiril--on average 6.6 +/- 3.0% on the first day and 12.2 +/- 3.8% on day 14. The total amount excreted increased by 34% on average, and was mainly due to an increased ramiprilat excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

The Pharmacokinetics of Ramipril in a Group of Ten Elderly Patients with Essential Hypertension

This open, general practice study looked at the pharmacokinetics of ramipril over a period of 1 year in elderly (greater than 65 years) hypertensive patients. Ten patients with a diastolic blood pressure between 95 and 125 mm Hg were treated with 5 mg of ramipril daily for 4 weeks, followed by an additional 11 months of treatment in which the dose was titrated against the blood pressure. Pharmacokinetic data were collected at baseline, 4 weeks, and 1 year. Mean peak concentrations of ramiprilat (the active diacid) were 11.5 ng/ml acutely, 18.5 ng/ml at 1 month, and 31.3 ng/ml at 1 year, and these were all statistically significantly different. Mean half-lives of ramiprilat were 5.5 h acutely, 5.2 h at 1 month, and 4.6 h at 1 year, and these were not statistically significantly different. Mean areas under the curve excluding the component for saturable binding were 106.8 ng/h/ml acutely, 115.7 ng/h/ml at 1 month, and 248 ng/h/ml at 1 year; the latter was statistically significantly different from the earlier readings. There is no evidence from this study that the pharmacokinetics change in any clinically relevant way.

The Pharmacokinetics of Ramipril in a Group of Ten Elderly Patients with Essential Hypertension

This open, general practice study looked at the pharmacokinetics of ramipril over a period of 1 year in elderly (>65 years) hypertensive patients. Ten patients with a diastolic blood pressure between 95 and 125 mm Hg were treated with 5 mg of ramipril daily for 4 weeks, followed by an additional 11 months of treatment in which the dose was titrated against the blood pressure. Pharmacokinetic data were collected at baseline, 4 weeks, and 1 year. Mean peak concentrations of ramiprilat (the active diacid) were 11.5 ng/ml acutely, 18.5 ng/ml at 1 month, and 31.3 ng/ml at 1 year, and these were all statistically significantly different. Mean half-lives of ramiprilat were 5.5 h acutely, 5.2 h at 1 month, and 4.6 h at 1 year, and these were not statistically significantly different. Mean areas under the curve excluding the component for saturable binding were 106.8 ng/h/ml acutely, 115.7 ng/h/ml at 1 month, and 248 ng/h/ml at 1 year; the latter was statistically significantly different from the earlier readings. There is no evidence from this study that the pharmacokinetics change in any clinically relevant way.

Pharmacokinetics of ramipril in hypertensive patients with renal insufficiency

In an open trial, the pharmacokinetics of ramipril and its active metabolite ramiprilat were studied in 25 hypertensive patients with various degrees of renal insufficiency given 5 mg ramipril p.o. for 14 days. Ramipril was rapidly absorbed and reached a peak concentration after 1-2 h. Cmax was greater in patients with severe renal insufficiency, which might indicate a reduced renal elimination rate, although, the rapid decline of the concentration-time curve for ramipril was almost independent of renal function. The mean initial apparent half-lives on Days 1 and 12, respectively, were 2.8 and 3.4 h (Group I: creatinine clearance 5-15 ml/min), 1.8 and 2.3 h (Group II: creatinine clearance 15-40 ml/min), and 1.9 and 1.9 h (Group III: creatinine clearance 40-80 ml/min). No accumulation was observed after multiple dosing. In contrast, the kinetics of its active acid metabolite ramiprilat was significantly influenced by renal function. The mean times to the peak plasma concentration were 5.7 h in Group I, 4.4 h in Group II and 3.8 h in Group III. The initial decline in plasma ramiprilat was dependent upon renal function; the mean initial apparent half-lives (Days 1 and 12, respectively) were 16.0 and 14.8 h (Group I), 10.1 and 9.5 h (Group II) and 10.6 and 8.0 h (Group III). Mean trough concentrations and absolute accumulation also increased with worsening renal function, and the renal clearance of ramiprilat was significantly correlated with the creatinine clearance. The subsequent long terminal phase at low plasma ramiprilat concentrations represented slow dissociation of the ACE-inhibitor complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Steady-State Kinetics of Ramipril in Renal Failure

In an open trial, the pharmacokinetics of ramipril and its active metabolite ramiprilat were studied in 23 hypertensive patients with various degrees of renal insufficiency. During a 2-week treatment period, each subject took daily a 5-mg tablet of ramipril. Serum profiles and urinary excretion of the parent compound and ramiprilat, the active metabolite, were then evaluated. Peak concentrations of ramipril were slightly greater in patients with severe renal insufficiency; however, most of the ramipril was metabolized in the liver. The drug concentration-time curve was almost independent of renal function and no accumulation was observed after multiple dosing. In contrast, ramiprilat kinetics were significantly influenced by renal function. Initial apparent half-lives (8-16 h), mean trough concentrations (5-19 ng/ml), and absolute accumulation all increased with worsening renal function, and renal clearance of ramiprilat was significantly correlated with creatinine clearance. The subsequent long terminal phase at low ramiprilat serum concentration represents the slow dissociation of the angiotensin converting enzyme (ACE)-bound drug. This study indicates that in patients with severe renal insufficiency (creatinine clearance below 30 ml/min), smaller doses of ramipril will be required than in patients with normal or borderline normal renal function.

Pharmacokinetics of ramipril in the elderly

Ramipril (HOE 498) is a pro-drug of which the main metabolite (HOE 498 diacid or ramiprilat) is a potent angiotensin converting enzyme inhibitor. Thirteen healthy white volunteers (5 females and 8 males, ages 65 to 76 years) participated in a study to investigate the pharmacokinetics of HOE 498 in the elderly. After administration of 10 mg of HOE 498, sequential urine and serum specimens were obtained for assay of HOE 498 and metabolites (HOE 498-glucuronide, diacid, diacid-glucuronide, diketopiperazine and diketopiperazine acid). Side effects, clinical chemistry and hematology were monitored. HOE 498 reached peak concentrations of 62.4 ± 23.3 ng/ml in serum after 0.7 ± 0.3 hours. Serum levels decreased with an apparent half-life of 0.9 ± 0.4 hours. The diacid was rapidly formed in serum, reaching peak concentrations of 40.6 ± 14.0 ng/ml after 2.0 ± 0.6 hours and declining with a half-life of 2.2 ± 0.5 hours. A prolonged terminal phase of serum concentration versus time curve was observed at concentrations <1 ng/ml. The mean recovery of HOE 498 and metabolites in urine, up to 26 hours after administration, was 35 ± 14% of the dose. The apparent half-lives, calculated from urine parameters, for HOE 498 and the diacid were 2.6 ± 0.9 and 4.0 ± 1.1 hours, respectively. The mean peak concentration and half-life of HOE 498 in serum are slightly higher in the elderly than in younger volunteers. Complete urinary collection was not possible, but urinary recovery did not seem different from younger volunteers.

Influence of renal function on the pharmacokinetics of ramipril (HOE 498)

The pharmacokinetics of ramipril (HOE 498) were studied after oral administration of a single 10 mg dose to 24 hypertensive patients with different degrees of renal function. The creatinine clearance ranged between 4.1 and 126 ml/min/1.73 m 2 and was below 35 ml/min/1.73 m 2 in 16 patients. Angiotensin converting enzyme activity and the concentrations of ramipril and its active diacid metabolite ramiprilat were measured in plasma up to 10 days after drug intake. Urine levels of ramipril, ramiprilat, their glucuronides and 2 major metabolites (a diketopiperazine and a diketopiperazine acid) were measured up to 4 days after medication. The plasma concentration-time curve of ramiprilat was poly-phasic with an initial steep decline after the peak level and a subsequent very long terminal phase at low concentrations. Impaired renal function resulted in higher peak levels of ramiprilat, longer times to peak and a markedly slower decline of plasma ramiprilat levels. Hence, the duration of angiotensin converting enzyme inhibition was considerably prolonged in renal failure and depended on the severity of renal impairment. The urinary excretion of ramipril and its metabolites decreased with decreasing renal function and was linearly related to the creatinine clearance, suggesting an alternative pathway of elimination. The pattern of excretion rates of ramipril and its various metabolites was not affected by renal failure. In contrast to the marked changes in the renal elimination, no relevant differences were observed in the absorption of ramipril from the gastrointestinal tract. Systolic and diastolic blood pressure decreased in all groups. The single 10 mg dose of ramipril was well tolerated.

Pharmacokinetics and effects on the renin-angiotensin system of ramipril in elderly patients

Converting enzyme inhibitors are likely to be prescribed with increasing frequency in elderly patients. The pharmacokinetics of ramipril, a new potent long-acting non-sulphydryl converting enzyme inhibitor, and its effects on blood pressure, plasma renin activity and angiotensin II concentrations were studied in a group of 8 elderly volunteers (mean age 77, range 61 to 84). Circulating concentrations of the active diacid formed from its parent drug were consistently higher in this group despite apparently normal renal function, assessed by serum creatinine and urea concentrations, compared with younger volunteers (age range 21 to 30). The initial dose of ramipril should be lower in older subjects. The study emphasizes the importance of careful extrapolation of data obtained from young volunteers to older subjects.

P-325 - Pharmacodynamics and pharmacokinetics of ramipril (Hoe 498), an angiotensin converting enzyme (ACE) inhibitor, in dogs

P-325 - Pharmacodynamics and pharmacokinetics of ramipril (Hoe 498), an angiotensin converting enzyme (ACE) inhibitor, in dogs