Pharmacokinetics of nitrendipine in terminal renal failure

Summary The pharmacokinetics and plasma protein binding of nitrendipine in patients with terminal renal failure have been compared with those in subjects with normal renal function.Kinetic parameters were calculated after a single 40 mg oral dose, an i.v. injection of 3 mg and after a 15 mg i.v. infusion of nitrendipine. Steady-state plasma levels were determined after 5 days of oral treatment with 20 mg b.d.Pharmacokinetic parameters and steady-state plasma levels in patients with renal failure did not differ from those in subjects with normal renal function.Nitrendipine was as highly bound to plasma proteins in patients with renal failure, as in subjects with normal renal function. The plasma protein did not differ between the two.The dosage of nitrendipine need not be modified for kinetic reasons in patients with renal failure.     

Pharmacokinetics of verapamil in patients with renal failure

Summary The pharmacokinetics of verapamil was studied in patients with end-stage chronic renal failure and in normal subjects after i.v. injection of 3 mg and a single oral dose of 80 mg. Plasma levels of verapamil and its active metabolite norverapamil were measured by HPLC. After i.v. injection, the terminal phase half-life and total plasma clearance of verapamil in both groups were similar. Haemodialysis did not change the time course of plasma verapamil levels after i.v. administration. After a single oral dose, the plasma levels of verapamil and norverapamil in both groups of subjects were similar. Subsequently, normal volunteers and patients with renal failure were treated for 5 days with oral verapamil 80 mg t.d.s. There was no difference between the 2 groups of subjects in the trough and peak levels of verapamil or of norverapamil. Intravenous and oral administration of the calcium channel blocking agent had similar effects on blood pressure, heart rate and the PR-interval in the electrocardiogram in both groups. The study demonstrated that the disposition of verapamil was similar in normal subjects and in patients with renal failure.Some of the results were presented at the Joint Spring Meeting of the German Pharmacological and Physiological Societies in Mainz, 1983 (Schols et al. 1983)     

Antisecretory effect and oral pharmacokinetics of omeprazole in patients with chronic renal failure

Summary The inhibitory effect of omeprazole on gastric acid secretion was tested in a group of patients on haemodialysis for chronic renal failure. Single 30 mg doses almost totally inhibited basal acid output on both dialysis and non-dialysis days. Plateau acid output was reduced by a mean of 77% and 90% on non-dialysis and dialysis days respectively. The absorption and pharmacokinetic profile of omeprazole were not affected by dialysis. Omeprazole was not recoverable from dialysis fluid. It is concluded that omeprazole is a potent inhibitor of gastric acid secretion in patients with chronic renal failure, and its effect is not influenced by haemodialysis.     

慢性肾衰患者血液透析时司帕沙星的药物动力学

目的 观察司帕沙星在慢性肾衰患者血液透析时的药物动力学特征.方法 用高效液相色谱法测定透析和非透析住院患者单剂量口服司帕沙星后血清和尿药物浓度,并计算药物动力学参数.结果 经PKNP-N_1药代动力学软件摸拟和计算,司帕沙星的药物动力学符合一级吸收二室开放模型,主要药动学参数:透析时T_(1/2(ka))=(1.25±0.57)h,T_(1/2β)=(11.88±4.13)h,T_(peak)=(4.18±0.78)h,C_(max)=(0.80±0.17)mg·L~(-1),AUC_(0~∞)=(6.90±3.25)mg·h·L~(-1)尿中24h原形药物排除率为(8.98±3.92)%;未透析时T_(1/2(ka))=(1.12±0.42)h,T_(1/2β)=(15．93±5．20)h,T_(peak)=(3.88±0.75)h,C_(max)=(0.69±0.37)mg·L~(-1),AUC_(0~∞)=(10.05±4.13)mg·h·L~(-1),尿中24h原形药物排出率为(10.58±5.64)%.结论 司帕沙星在慢性肾衰患者血液透析时消除加快.     

Pharmacodynamics and pharmacokinetics of oral nitrendipine solution in hypertensive patients with advanced renal failure

Summary Nitrendipine solution 5 mg·ml^–1 in the dose of 5 mg was given orally to 20 patients with chronic renal failure and elevated diastolic blood pressure (110 mmHg), of whom 10 were on maintenance haemodialysis (endogenous creatinine clearance <5 ml·min^–1) and 10 were at the predialysis stage (endogenous creatinine clearance 5–20 ml·min^–1).The aim of the study was to investigate the influence of kidney function and/or dialysis treatment on the pharmacokinetic and pharmacodynamic profile of a solution of nitrendipine and to assess its antihypertensive efficacy.After 10 min there was a significant reduction in blood pressure from 188/113 to 173/100 (patients not dependent on dialysis) and from 197/112 to 161/94 mmHg (patients dependent on dialysis). The maximum fall in blood pressure (approximately 30%) was attained after 90 min in the dialysis patients and after 120 min in the non-dialysis group. Blood pressure increased again about 3 h after the administration of nitrendipine but it was still below baseline after 12 h. The terminal elimination half-life (4.1 h in the dialysis patients and 3.6 h in non-dialysis patients) was similar to that observed in patients with normal renal function. The pharmacokinetics of nitrendipine did not differ between the dialysis and non-dialysis groups. There was a correlation between plasma concentration and the blood pressure reduction. The maximum plasma concentration of nitrendipine was reached after 0.5 h (median) and did not differ between the two groups. The mean maximum plasma concentration was 14.8 g·1^–1 in the study population as a whole, with comparable means in the dialysis (17.3 g·1^–1) and non-dialysis (12.4 g·1^–1) groups.The nitrendipine solution proved to be effective in lowering acutely elevated blood pressure in patients with advanced renal failure and renal hypertension, and was well tolerated. The pharmacokinetics was not affected by renal impairment or by dialysis.     

The pharmacokinetics of nifurtimox in chronic renal failure

Summary The pharmacokinetics of nifurtimox, a drug used in the treatment of Trypanosoma cruzi infections, has been studied in seven patients with chronic renal failure undergoing haemodialysis, and in seven healthy subjects.Each subject took nifurtimox 15 mg·kg^–1 orally and blood samples were obtained for 10 h after administration. Nifurtimox in serum was analyzed by HPLC.The patients with chronic renal failure had a higher C_max than the control subjects due to a change in systemic availability. An alternative explanation would be that both the distribution volume and the clearance had changed.The mean half-life in the patients with chronic renal failure was similar to that in the healthy subjects.     

兔急性肾功能衰竭对盐酸四甲基吡嗪药物动力学的影响

目的 :研究盐酸四甲基吡嗪 (TMPH)在正常肾功能与急性肾功能衰竭 (ARF)家兔体内的药物动力学变化。方法 :正常组和肾衰组家兔均分别按TMPH 10mg·kg-1和 30mg·kg-1,iv。以气相色谱法测定不同时相点的血药浓度 ,应用 3P97药物动力学程序处理 ,求得各药物动力学参数。结果 :TMPH药 时曲线均符合二室开放模型。肾衰组药 时曲线出现肩峰。结论 :家兔ARF改变正常药物动力学变化规律     

慢性肾功能衰竭患者环丙沙星药物动力学研究

对８例健康志愿者，１１例慢性肾功能衰竭患者（Ｃｃｒ＜１０ｍｌ／ｍｉｎ）静脉恒速滴注乳酸环丙沙星２００ｍｇ（３０ｍｉｎ）注射液后的临床药物动力学进行了研究，用高效液相色谱法对血清中环丙沙星进行测定，主要药动学参数分别是滴注完时浓度Ｃｏ健康人组为２．２６ｍｇ／Ｌ，未透析组为２．５２ｍｇ／Ｌ，血透组为２．３７ｍｇ／Ｌ，腹透组为２．３５ｍｇ／Ｌ。清除相半衰期健康人为２．７±０．８ｈ，未透析组为１５±４ｈ，血透组为５．０±１．９ｈ，腹透组为６．３±２．７ｈ。表明慢性肾功能衰竭患者的环丙沙星药物动力学过程较健康者有明显的改变，根据以上数据提出慢性肾功能衰竭时的一些给药方案     

Effect of uranyl nitrate-induced acute renal failure on the pharmacokinetics of sulfobromophthalein in rats

The effect of acute renal failure (ARF) on the pharmacokinetics of sulfobromophthalein (BSP) was investigated in order to elucidate if renal failure modifies the hepatic metabolism of drugs. ARF was induced by intravenous (iv) injection of uranyl nitrate (UN) to rats (5 mg/kg) five days before the experiment. Area under the plasma concentration-time curve (AUC) of BSP after portal vein (pv) injection increased by 2-fold and total body clearance (CL _t) decreased one half (p<0.01) in UN-induced ARF (UN-ARF) rats compared to the control rats. But the plasma disappearance of BSP afteriv injection did not differ significantly between control and UN-ARF rats. Since BSP is excretedvia the liver,CL _t representd the approximate hepatic clearance of BSP. Therefore, the decrease inCL _t represents a decrease in hepatic intrinsic clearance (CL _int) for BSP since plasma free fraction (f _p) of BSP was not affected by UN-ARF. The content of hepatic cytoplasmic Y-protein, which catalyzes BSP-glutathione conjugation and limits the transfer of BSP from blood to bile, increased significantly (p<0.01), however its binding activity (BA) for BSP was decreased significantly (p<0.01) by UN-ARF. The decrease inCL _int might have some correlation with the changed characteristics of hepatic Y-protein, specifically its decreased BA for BSP.     

硝苯地平控释片与普通片治疗老年高血压病比较

目的 比较硝苯地平控释片与普通片对老年高血压患者的降压疗效。方法 采用随机、单盲的方法，对８４例老年高血压患者进行２４ｈ动态血压监测，比较其疗效及副反应。结果 两药均能显著降低老年高血压患者的偶测血压及２４ｈ平均血压（Ｐ〈０．０１）。两药在降低偶测压缩压、２４ｈ平均收缩压及白天平均血压幅度方面差异无显著性（Ｐ〉０．０５），硝苯地平控释片能明显降低患者的偶测舒张压（Ｐ〈０．０５）、２４ｈ平均舒张压（     

The pharmacokinetics of single doses of metoclopramide in renal failure

Summary The pharmacokinetics of metoclopramide have been studied after intravenous and oral dosing (10 mg) to 6 patients with chronic renal failure. The mean terminal half-life was 13.9 h after intravenous and 14.8 h after oral administration. Total body clearance after i. v. dosing was 16.7 l/h. Oral bioavailability was 71.8%. In comparison to previous studies on normal subjects these results indicate that clearance of metoclopramide in renal failure is approximately 30% of normals. This difference is not accounted for by the change in renal clearance and suggests impaired metabolism or an alteration in enterohepatic circulation of metoclopramide in renal failure.     

Clinical pharmacokinetics of bezafibrate in patients with impaired renal function

Summary The pharmacokinetics of the new lipidlowering drug bezafibrate has been investigated in patients with impaired renal function and hyperlipoproteinaemia. 12 patients received a single oral dose of bezafibrate 300 mg. Plasma and urine samples were collected and bezafibrate was analyzed by gas chromatography. Eight of the patients had moderately impaired renal function, with a creatinine clearance between 20 and 40 ml/min; the mean plasma half-life of bezafibrate in them was 7.8±3.9 h (SD) and the plasma clearance was 0.03±0.02 l/kg · h. Three of the patients had a creatinine clearance>40 ml/min; in them the plasma half-life was shorter, 4.6±1.2 h, and the plasma clearance was higher, 0.06±0.01 l/kg · h. The slowest elimination of bezafibrate was found in a patient with a creatinine clearance of only 13 ml/min. This patient had a plasma half-life of 20.1 h, which is ten times longer than has been reported in healthy volunteers. Thus, when treating hyperlipoproteinaemia in patients with impaired renal function, the dosage of bezafibrate must be individualized because of its reduced renal elimination.     

Clinical pharmacokinetics and pharmacodynamics of fazadinium in renal failure

Summary The pharmacokinetic behaviour and neuromuscular blockade produced by the administration of fazadinium bromide at a dose of 1 mg/kg have been studied in seven patients with end-stage renal failure. No significant differences were found in the pharmacokinetic or pharmacodynamic properties when compared with patients with normal renal function. It is suggested that fazadinium may be superior to either d-tubocurarine or pancuronium in providing muscle relaxation for patients with renal failure.     

Kinetics of morphine in patients with renal failure

Summary The kinetics of morphine and its glucuronidated metabolites were investigated in seven patients with advanced renal failure. The terminal elimination half life of morphine varied between 1.5 and 4.0 h (mean 2.4 h), the volume of distribution between 2.5 and 6.3 l·kg^–1 (mean 4.4 l·kg^–1) and the total plasma clearance between 13.3 and 31.3 l·min^–1·kg^–1 (mean 21.1 l·kg^–1). There were no statistically significant differences between the pharmacokinetic data in the uraemic patients and in a control group of cancer patients with normal kidney function. The concentrations of the glucuronidated metabolites rapidly rose to levels above those of morphine. The elimination half-life of M3G varied between 14.5 and 118.8 h (mean 49.6 h) in the renal failure patients, which is distinctly different from the 2.4 to 6.7 h (mean 4.0 h) found in patients with normal kidney function. There was a significant correlation between the half-life of M3G and renal function estimated as serum urea. Thus, the metabolism of morphine in patients with kidney disease is not significantly impaired. The clinical importance of the high concentrations of glucuronides in uraemic patients is not known.     

硝苯地平对氨茶碱血药浓度及药动学参数的影响

本文采用紫外分光光度法对单用氨茶碱及氨茶碱与硝苯地平合用后,家兔体内茶碱血药浓度进行了测定,并对两组药动学参数进行了统计学处理,结果表明,硝苯地平略使氨茶碱血药浓度升高,但药动学参数无显著变化。     

Pharmacokinetics of quinine in patients with chronic renal failure

Methods: We investigated the pharmacokinetics of quinine (Qn) following administration of a single oral dose of 600 mg Qn sulphate in six male Thai patients with a moderate degree of chronic renal failure (CRF), and six male Thai subjects with normal renal function. Results: The drug was well tolerated in both groups of subjects; no major adverse reactions were observed. A marked alteration in the pharmacokinetics of Qn was found in patients with CRF compared to healthy subjects; there were six signifiicant changes in the pharmacokinetic parameters. Absorption was delayed, but increased in CRF (t_max 4.5 vs 1.6 h, C_max 6.17 vs 3.45 g·ml^–1). Total clearance was significantly reduced 0.94 vs 2.84 ml·min^–1·kg^–1, whereas V_z/f remained unchanged (1.82 vs 2.78 1·kg^–1). This resulted in the increased values of AUC and prolongation of the t_1/2z and MRT in the patients (AUC 181.5 vs 61.8 g·min^–1·ml^–1, t_1/2z 26 vs 9.7 h, MRT 36.4 vs 11.3 h). Median concentrations of plasma unbound fraction of Qn collected at 4 h after drug administration in patients and healthy subjects were 7.3 vs 9.8%, respectively.     

Elimination and haemodynamic effects of nitrendipine in patients with chronic renal failure

Summary In sixteen patients with arterial hypertension and differing degrees of renal function the pharmacokinetics and haemodynamic effects of nitrendipine have been studied after treatment for 7 days. The AUC (0–24) and the elimination half-life of nitrendipine were significantly increased; the AUC (0–24) in patients with renal failure (median creatinine clearance 27.1 ml × min^–1) was 196 ng × ml^–1 × h compared to 97.8 ng × ml^–1 × h in control subjects (median creatinine clearance 94.4 ml × min^–1). The corresponding elimination half-lives were 13.5 h in renal failure and 4.4 h in the controls. The haemodynamic effects of nitrendipine were not enhanced in the patients.     

Lisinopril in hypertensive patients with and without renal failure

Summary Lisinopril (MK521), a lysine analogue of enalaprilic acid, the bioactive metabolite of enalapril, has a longer half-life than enalaprilic acid, and is excreted unchanged in the urine. Its kinetic profile and antihypertensive and hormonal effects have been investigated in an open study in 3 groups each of 6 hypertensive patients, with normal, moderate and severe impairment of renal function. Serum drug level, blood pressure, converting enzyme activity (CEA), plasma renin activity (PRA), aldosterone concentration (PAC), and serum potassium and creatinine were measured during 1 week following a single oral dose and subsequently following 8 daily doses of 5 mg lisinopril. Accumulation of lisinopril was found in the severe renal failure group. CEA was suppressed to less than 10% of its initial value from 4 to 24 h after the initial dose in all three groups, and the suppression was more marked and lasted longer in patients with severe renal failure. An inverse correlation was found in all patients between log serum lisinopril concentration and log CEA. Lisinopril lowered blood pressure in all three groups over 24 h. PRA rose and PAC fell similarly in the groups. Serum potassium increased in the renal failure groups and creatinine remained unchanged in all groups.Thus, when lisinopril 5 mg is given daily to patients with severe renal failure it may accumulate. The high serum lisinopril concentration does not cause an excessive antihypertensive effect. In patients with severe renal failure, adjustment of the dose or the dosing frequency to the degree of renal failure is recommended to avoid administration of doses in excess of those required to achieve adequate inhibition of converting enzyme.     

Protein binding of tolfenamic acid in the plasma from patients with renal and hepatic disease

Summary The protein binding of tolfenamic acid in plasma from patients with renal and hepatic disorders was studied by equilibrium dialysis. Drug binding to the cellular components of whole blood and blood cell suspensions was also measured. Salicylic acid was used as the reference drug in all experiments. Renal and hepatic diseases increased the unbound fraction of tolfenamic acid. Free drug fractions were significantly correlated with changes in creatinine, urea, and total bilirubin, but not with those in albumin or total protein in plasma. Comparison of the theoretical binding parameters in control plasma and similar changes in protein binding in all the plasma samples studied revealed that tolfenamic acid and salicylic acid probably share a common primary binding site. The significance of the correlation permits use of salicylic acid as a model drug for predicting changes in the protein binding of tolfenamic acid. The measurements of binding properties in whole blood and blood cell — buffer suspension showed that tolfenamic acid interacts with the lipid membrane structures of blood cells, while salicylic acid is distributed into the aqueous cell space.This paper is based on a scientific cooperation agreement between the University of Tampere, Tampere, Finland, and Charles University, Prague, Czechoslovakia