Biomedical subjects
Heinrich Knauf
Publications and source records attributed to Heinrich Knauf.
[Sequential nephron blockade].
Explore the source record for details and available documents.
[Mechanism of action of xipamide and its classification as a "low ceiling diuretic". Pharmacodynamic-pharmacokinetic studies in healthy volunteers and in kidney and liver patients].
Xipamide (CAS 14293-44-8) shows structural features comparable with the thiazide- as well as the class of loop diuretics. According to earlier findings this diuretic, in contrast to the thiazides, should not decrease the glomerular filtration rate (GFR) and be effective even in patients with advanced renal failure. Therefore recently the question, which class of diuretics xipamide should be related to, has been increasingly discussed. In order to solve this issue, the diuretic effect of xipamide was assessed in healthy volunteers once without and once under strict water and salt restriction. Additionally, changes in GFR were monitored by means of measurement of the creatinine clearance. Kinetic parameters were determined in plasma and urine; further, in patients with liver cirrhosis, renal elimination kinetics of the diuretic were correlated with the concentration of direct plasma bilirubin, as a marker of cholestasis, at the beginning of a treatment with xipamide, 40 mg qd. The investigations proved that xipamide, like a typical thiazide diuretic, gives rise to a temporary decrease in GFR of about 30 %, provided the renin-angiotensin-aldosterone system of the volunteer is activated by previous salt and water restriction. Xipamide leads to an increase of K+ and Mg2+ excretion, but to a decrease of Ca2+ excretion in urine, a charactaristical feature of the thiazide-like diuretics. The correlation between Na+ excretion and drug excreted in urine over time showed a functional graph that is characteristic for a "low ceiling" thiazide diuretic. In patients with renal failure FE(Na) was increased when related to the GFR-adjusted drug excretion rate, whereas it was diminished in conditions with decreased effective circulating volume like in liver cirrhosis with ascites. It could be shown that the elimination kinetics of xipamide are determined by renal drug clearance, which proportionally decreases with GFR. In patients with liver failure, a decrease of non-renal drug clearance went along with an increase in urinary drug excretion. The amount of drug excreted in urine (Ae) proportionally increased with the concentration of the patients' direct plasma bilirubin. Thus, from a pharmacological as well as clinical point of view xipamide acts like a thiazide diuretic. As could be shown for other thiazides some time ago, xipamide is effective not only in patients with cardiovascular diseases, but also in those with advanced renal failure.
Evaluation of long-term efficacy and acceptability of indapamide SR in elderly hypertensive patients.
OBJECTIVE: To assess the long-term antihypertensive efficacy and acceptability of indapamide SR 1.5 mg in elderly hypertensive patients (> or = 65 years). STUDY DESIGN: Open, 12-month, follow-up study of 444 patients, treated with indapamide SR, who were responders and/or achieved target BP levels following a 3-month, randomised, controlled, double-blind short-term comparison of indapamide SR versus hydrochlorothiazide 25 mg and amlodipine 5 mg. RESULTS: The long-term decrease in systolic blood pressure (SBP)/diastolic blood pressure (DBP) after 12 months follow-up with indapamide SR was -24.0/-13.1 mmHg from baseline (M0). The percentage of patients that achieved target BP levels (DBP < 95 mmHg, SBP < or = 160 mmHg) was 80.1% [84.3% for isolated systolic hypertension (ISH) subgroup], and the response rate (BP < 140/90 mmHg or decrease in supine diastolic BP > or = 10 mmHg or in supine systolic BP > or = 20 mmHg) 81.5%. Blood pressure (BP) remained stable throughout the 12 months follow-up period (M3-M15), whatever the previous treatment received during the 3-month, doubleblind period (M0-M3). Clinical and biological acceptability was good. A low occurrence of withdrawals (7.2%), was reported. CONCLUSION: Over the course of the long-term, 12-month follow-up study, indapamide SR was shown to be an effective and well tolerated antihypertensive therapy, even after a switch from amlodipine or hydrochlorothiazide, in patients aged 65 years-80 years with systolo-diastolic hypertension (SDH) or ISH.