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Biomedical subjects

B Beermann

Publications and source records attributed to B Beermann.

At least 73 records · Page 4Linked to original sources
PubMed1983

Coupling between renal tubular secretion and effect of bumetanide.

The relationship between renal tubular secretion of bumetanide and its saluretic effect was studied in six healthy subjects before and after probenecid (1 gm IV). Bumetanide was determined in serum and urine by HPLC. Continuous intravenous infusion of bumetanide (200 micrograms/hr) gave an average diuresis at steady state of 15 +/- 3 ml/min. Corresponding plasma concentration, urinary excretion rate, and renal clearance of bumetanide averaged 14.3 +/- 2.3 ng/ml, 64 +/- 31 micrograms/30 min, and 145 +/- 59 ml/min. After probenecid there was a marked change in bumetanide kinetics. Average plasma concentration rose to 41.7 +/- 8.1 ng/ml, whereas renal clearance and urinary excretion rate fell to 15.1% and 29.5% of control. There was also a concomitant decrease in diuresis and saluresis to 47% and about 40% of control. Probenecid also reduced the renal clearance of para-aminohippurate and inulin to 67% and 75% of control. Since the fractional water and sodium chloride excretion was also reduced about 33% and 42%, it is concluded that a large part of the diuretic effect of bumetanide depends on its active tubular secretion. As with furosemide and piretanide, bumetanide diuresis is elicited from the luminal side of the human nephron.

Adult↗
PubMed1983

Disposition of chloroquine in man after single intravenous and oral doses.

1 Chloroquine was given in 300 mg single doses as an i.v. infusion, an oral solution and as tablets at intervals of at least 56 days to 11 healthy volunteers. Concentrations of chloroquine and its metabolite desethylchloroquine were measured in plasma, erythrocytes and urine using h.p.l.c. 2 Chloroquine was detectable in all plasma samples up to 23 days and occasionally up to 52 days after dosage. Urinary concentrations were monitored up to 119 days. The disposition pattern was multiexponential reflecting extensive tissue binding of the drug. 3 After i.v. dosing the volume of distribution ranged from 116 to 285 l/kg and the apparent terminal half-life from 146 to 333 h. Total plasma clearance +/- s.d. was 712 +/- 166 ml/min and renal clearance 412 +/- 139 ml/min. The mean estimated urinary recovery of chloroquine was 47%, 42% and 46% after i.v., oral solution and tablets indicating nearly complete bioavailability. The corresponding figures for the metabolite were 7%, 10% and 12%. 4 The disposition of chloroquine in erythrocytes was parallel to that in plasma. The concentrations in erythrocytes were consistently 2 to 5 times higher than in plasma. 5 Subjective side effects like difficulties with swallowing and accommodation, diplopia and fatigue occurred during intravenous infusion and were closely related to plasma concentrations. No effect was seen on the electrocardiogram, mean arterial blood pressure and pulse rate. No adverse reactions were observed after the oral doses. High frequency audiometry did not reveal any significant hearing impairment for the group as a whole.

Administration, Oral↗
PubMed1983

Diuretic effect and pharmacokinetics of tizolemide in subjects with normal and decreased renal function.

Tizolemide, a new sulphonamide diuretic, has alkaline properties and is cleared by a tubular transport system which differs from the PAH-excreting system which transports thiazide diuretics. The effect of this drug on the excretion of sodium and other electrolytes, and its pharmacokinetics, were evaluated in 5 healthy volunteers and in 10 patients with renal disease who had GFRs ranging from 5-98 ml/min. The saluretic effect of tizolemide was compared with that of placebo. The increase in sodium and chloride excretion after a single dose of 50 mg i.v. was clearly dependent on residual renal function but could be observed in all except one patient. It remains to be assessed whether a full diuretic effect can be achieved in patients with renal insufficiency if higher doses are used. The plasma half-life was 3.0 hours in healthy subjects but increased in patients with renal insufficiency to a maximum of 52 hours. In normal subjects total plasma clearance (611 ml/min) mainly depended on the renal clearance (564 ml/min) which decreased in proportion to GFR, whereas non-renal clearance remained unchanged. The large apparent volume of distribution of the drug (166 l/1.73 m2 BSA) did not increase significantly in uremia. Clinical trials with this drug in patients with reduced renal function must take into account the expected prolongation of its half-life.

Adult↗
PubMed1983

Renal tubular secretion of piretanide and its effects on electrolyte reabsorption and tubuloglomerular feedback mechanism.

Piretanide [HOE 118; 4-phenoxy-3-(1-pyrrolidinyl)-5-sulfamoxylbenzoic acid] is a new diuretic with a saluretic effect similar to that of furosemide. The present experiments were undertaken to investigate if transport of piretanide into the tubular lumen determines the diuretic response and what effect piretanide has on the tubuloglomerular feedback control and loop of Henle electrolyte transport. To study the first question, five healthy subjects were investigated. Piretanide, inulin and p-aminohippuric acid were continuously infused. After equilibration, 1 g of probenecid was given which reduced the tubular secretion of piretanide to one-sixth of control level. The reduction in diuresis was 41.4% while it was 59.5, 63.9 and 45.8% for the urinary excretion of chloride, sodium and potassium, respectively. In a second series of experiments in rats a proximal tubular stop-flow pressure response at increased distal delivery of fluid was measured when Ringer's solution, Ringer's solution plus furosemide (10(-4) M) or bumetanide (5 X 10(-5) M) or piretanide (10(-4) M and 5 X 10(-5) M) was added to the tubular perfusion solution. The results indicate that the feedback could be completely blocked by any of these diuretics. The fluid absorption in the loop of Henle was studied in separate experiments and the addition of piretanide (10(-4) M) greatly reduced chloride and absolute fluid absorption from this nephron segment. The present results indicate that tubular secretion of piretanide is important for the diuretic response and that piretanide inhibits the fluid absorption in the loop of Henle and the tubuloglomerular feedback control which would otherwise blunt the diuretic response with a reduction in glomerular filtration rate.

Diuretics↗
PubMed1982

Kinetics and dynamics of furosemide and slow-acting furosemide.

Bioavailability and dynamics of a sustained-release preparation of furosemide (FR, 60 mg) were compared with those of a conventional tablet (F, 40 mg). The preparations were given to 12 healthy subjects in a study of crossover randomized design once daily for a week. FR absorption was substantially delayed and the uptake of furosemide was about 75% of that from F, despite the larger dose administered. F induced a brief, intense diuresis and excretion of Na+, K+, and Cl-, both during short- and long-term administration. There was no such peak after FR. Total diuretic and saluretic effects did not differ between the two preparations, despite the lower bioavailability of FR. It is suggested that this discrepancy might be caused by transient supramaximal urinary levels of furosemide after F, whereby not all of the drug can exert an effect.

Adult↗
PubMed1981

Fine tuning a laundry.

Explore the source record for details and available documents.

Hospital Bed Capacity, 500 and over↗
PubMed1981

Pharmacokinetics of heparin in healthy and obese subjects and in combination with dihydroergotamine.

Heparin (5000 IE s.c., 5000 IE i v, 200 EI/kg i v) was given to healthy volunteers without and with 0.5 mg dihydroergotamine (DHE) i v to test whether DHE influences the kinetics of heparin. The anticoagulant (200 IE/kg) was also administered to obese subjects. Heparin was assayed using a chromogenic substrate for activated factor X. The plasma levels of heparin did not differ whether given concomitantly with DHE or not. Halflife of heparin was also uninfluenced of DHE demonstrating that the beneficial effect of DHE on postoperative thromboembolism is not caused by interaction with the pharmacokinetics of heparin. The plasma levels of heparin were significantly higher in the obese subjects than in the normal ones. The halflife of the drug averaged 2.13 h in the obese subjects and 1.36 h in the normal subjects (P less than 0.02). It was concluded that the heparin dosage should be calculated in terms of estimated ideal weight.

Dihydroergotamine↗
PubMed1980

Renal tubular secretion and effects of furosemide.

Continuous intravenous infusion of furosemide (8 mg/hr) to 6 healthy subjects induced an average diuresis at steady state of 667 +/- 144 ml/30 min (+/- SD) with a mean plasma concentration of furosemide of 623 +/- 209 ng/ml. The urinary output of Cl- was 50.4 +/- 7.5, of Na+ 47.7 +/- 8.7, and of K+ 5.4 +/- 0.6 mmole/30 min. Intravenous injection of probenecid (1 gm) raised the plasma furosemide level to a maximum of 1,584 +/- 151 ng/ml. Despite this, the urinary excretion of water, Cl-, Na+, and K+ decreased to 52%, 39%, 39%, and 52%, respectively, of control values. Probenecid greatly reduced the urinary excretion and renal clearance of furosemide. There was no or negative correlation between the plasma levels of furosemide and its diuretic and saluretic effects. The urinary excretion and renal clearance of the diuretic correlated positively with these effects. No effect of probenecid on protein binding of furosemide was detected. The findings show that the diuretic effects of furosemide depend on active tubular secretion of the drug and thus on its tubular fluid concentration.

Adult↗
PubMed1980

Placental transfer of hydrochlorothiazide.

The concentrations of hydrochlorothiazide (HCT) in maternal and umbilical cord plasma and in amniotic fluid were determined at partus in 10 pregnancies. The levels of HCT in umbilical cord plasma were 0.1--0.8 of that in maternal plasma. The concentrations of the diuretic in amniotic fluid were up to 5 and 19 times higher than in maternal and umbilical cord plasma, respectively.

Amniotic Fluid↗
PubMed1979

Pharmacokinetics of hydrochlorothiazide in patients with congestive heart failure.

1. Hydrochlorothiazide (HCT, 50-75 mg) was administered orally to seven patients with cardiac failure. 2. Plasma levels and urinary concentration of HCT were determined by GLC. 3. The gastrointestinal uptake of the diuretic in three patients was reduced to approximately half that seen in healthy controls. 4. Plasma halflife of HCT was correlated with endogenous creatinine clearance. 5. Pharmacokinetics of HCT are considerably changed in cardiac failure.

Aged↗
PubMed1978

Enhancement of the gastrointestinal absorption of hydrochlorothiazide by propantheline.

Hydrochlorothiazide 75 mg was given twice p.o. to fasting subjects. In the second study they had been pretreated with propantheline 60 mg. Plasma and urine concentrations of hydrochlorothiazide were determined by GLC. Pretreatment with propantheline on average delayed the maximal plasma level of hct from 2.4 to 4.8 h (p less than 0.05); and the total urinary recovery of hydrochlorothiazide by 48 h was increased from 49.3 mg to 66.9 mg (p less than 0.005). It was concluded that propantheline increased substantially the absorption of the diuretic.

Adolescent↗
PubMed1978

Antihypertensive effect of various doses of hydrochlorothiazide and its relation to the plasma level of the drug.

Nine previously untreated hypertensive patients (WHO Stage I and II) were given hydrochlorothiazide (hct) 12.5, 25, 50 and 75 mg for two weeks after an initial four week period of placebo treatment. Blood pressure recordings were made casually and after 30 min rest in lying, sitting and standing positions. Plasma concentrations of the drug were measured by GLC. A significant decrease in BP was seen during treatment with hct 12.5 mg except in the casual standing position. Doubling of the dose twice produced very little further decrease in BP. The mean steady state concentration was 111 ng.ml-1 during treatment with hct 75 mg. A linear relationship was found between the plasma concentration of hct at 0 and 5 h and the various dose level of hct. No relation was found between plasma concentration and reduction in blood pressure.

Aged↗
PubMed1978

Pharmacokinetics of bendroflumenthiazide in hypertensive patients.

After four weeks on placebo treatment, 8 hypertensive patients (WHO stage I) were treated for 2 weeks with bendroflumethiazide (bft) 2.5 mg and KCl 1.5 g daily. Subsequently they received bft 5 mg and KCl 1.5 g daily for a further fortnight. At the end of each period of treatment blood pressure was recorded and blood samples and urine were collected for analysis of bft by GLC. Before taking the daily dose of bft, no trace of the drug was found in plasma. Peak levels of bft were seen after 2.3 h and averaged 23 and 50 ng . ml-1 after 2.5 and 5 mg, respectively. After bft 2.5 mg the plasma level was too low for kinetic analysis. The plasma half-life after 5 mg averaged 4.1 h. The mean apparent volume of distribution was 1.18 1 . kg-1. Non-renal clearance averaged 200 ml . min-1. The renal clearance of bft was significantly lower (p less than 0.05) after 5 mg (48 ml . min-1) than after 2.5 mg bft (93 ml . min-1), although the creatinine clearance remained unchanged. No correlation was found between the plasma level of bft and its effect on blood pressure.

Adult↗
PubMed1978

Gastrointestinal absorption of hydrochlorothiazide enhanced by concomitant intake of food.

Hydrochlorothiazide (hct) 75 mg was administered orally to eight healthy volunteers without (Study I) or together with a standaridized meal (Study II), and plasma and urine concentrations of hct were analyzed by GLC. The plasma levels of hct were higher initially when the tablets were taken on an empty stomach, but after 5 h they were higher in Study II. There was no difference between the two studies in the area under plasma concentration time curves. The urinary recovery of hct totalled 55.6 +/- 4.9 mg when the drug was given with food and 47.4 +/- 6.0 when it was taken on an empty stomach. The difference is significant (p less than 0.01). As the urinary recovery represents the uptake of hct, it appears that the gastrointestinal absorption of hct is enhanced when the drug is given with food.

Adolescent↗