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Biomedical subjects

D Förster

Publications and source records attributed to D Förster.

At least 37 records · Page 2Linked to original sources
PubMed1983

Interactions between mezlocillin and sisomicin in vitro and in patients with normal and various degrees of impaired renal function.

During in vitro experiments using pooled human plasma at 37 degrees C, sisomicin alone showed only a small loss of activity of 12% in 24 hr. Incubation with 80 micrograms/ml mezlocillin did not alter the rate of inactivation. But, after the addition of 300 micrograms/ml mezlocillin to either 5.0 or 2.5 micrograms/ml sisomicin, the sisomicin half-life was reduced by 50% and 100% respectively. When the mean drug concentration ratios are compared, inactivation of sisomicin by mezlocillin was significantly less than that reported for carbenicillin or ticarcillin. Sisomicin pharmacokinetics were studied in 27 patients with normal and various degrees of impaired renal function (Part A) and were not changed by the simultaneous administration of mezlocillin 60 mg/kg (Part B). Furthermore, even in far advanced renal insufficiency, sisomicin inactivation by mezlocillin could not be demonstrated. The differing results obtained with mezlocillin compared to carbenicillin or ticarcillin might be explained by differences in the physico-chemical properties of the drugs in addition to the different kinetic behavior of mezlocillin in patients with impaired renal function.

Adolescent↗
PubMed1982

Effect of linoleic acid-rich diet on blood pressure, lipids, catecholamines, and dopamine -beta-hydroxylase in spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) and normotensive Wistar rats were fed a linoleic acid-rich (LAR) and -deficient (LAD) diet for 22 weeks, respectively. Although linoleic acid (LA) and arachidonic acid (AA) in serum and liver triglycerides markedly increased after a LAR diet, LA was significantly lower and AA was higher in SHR when compared to normotensive control rats. Thus, the percentage of both fatty acids remained different like in animals fed a commercial diet. On the contrary, in SHR and normotensive rats fed a LAD diet no differences in the LA and AA content could be found between the groups. In these rats, however, n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) in serum triglycerides were increased. Blood pressure, serum triglycerides and total cholesterol appeared unchanged, whereas HDL-cholesterol was increased after a LAR diet. Dopamine, adrenaline and noradrenaline content as well as dopamine-beta-hydroxylase activity were augmented in adrenal glands of SHR fed a LAR diet. In spite of distinct biochemical alterations the genetically determined hypertension in rats could not be influenced by a long-lasting diet containing a high amount of LA which has been proved to be effective on lowering blood pressure in other hypertensive rat models.

Animals↗
PubMed1980

[Concentrations of mezlocillin in cerebrospinal fluid in vira meningitis (author's transl)].

The concentrations of mezlocillin in the cerebrospinal fluid were measured in ten patients with viral meningitis after a single infusion of 5 g lasting 30 minutes. One to two hours after infusion the CSF concentrations were between 0.1 mcg/ml and 1.6 mcg/ml, and thus exceeded the minimal inhibitory concentrations of Neisseria meningitidis and Diplococcus pneumoniae, the most common pathogens in bacterial meningitis in adults. The minimal inhibitory concentration of ampicillin-sensitive strains of Haemophilus influenzae was also attained. Further investigations must be carried out, in order to ascertain whether higher CSF concentrations are attained in bacterial meningitis.

Adolescent↗
PubMed1980

Effects of impaired renal function, hemodialysis, and peritoneal dialysis on the pharmacokinetics of mezlocillin.

The pharmacokinetics of mezlocillin were examined in 8 patients with normal renal function (inulin clearance, > 80 ml/min per 1.73 m2), 32 patients with moderately reduced renal function (inulin clearances, 80 to 5 ml/min per 1.73 m2), and 12 patients maintained by hemodialysis or peritoneal dialysis because of severely impaired renal function. A single dose of 60 mg of mezlocillin per kg of body weight was infused intravenously over 30 min. Antibiotic concentrations in plasma, urine, and dialysate were determined by the agar diffusion technique. The half-life of mezlocillin increased with decreasing renal function from an average of 53 min in subjects with normal function to 165 min in oligoanuric patients. The urinary recovery of this drug in 24 h decreased from 65% at a glomerular filtration rate of 92 ml/min to 7.6% at a glomerular filtration rate of 6.7 ml/min. Volume of distribution was not changed by the renal insufficiency, amounting on the average to 22.5% of body weight. Intermittent hemodialysis or peritoneal dialysis contributed to only a minor degree to the 24-h mezlocillin kinetics. The pharmacokinetic properties of mezlocillin permit a normal dosage over wide ranges of renal insufficiency; however, when the glomerular filtration rate is below 10 ml/min, the dosage interval should be increased from 8 to 12 h.

Adolescent↗
PubMed1979

[The biliary excretion of azlocillin].

The excretion of azlocillin into the human biliary tract was investigated in 8 patients with a T-tube in the common bile duct after intravenous injection of 2 g. Samples of serum and common duct bile were assayed from 15 min to 12 hours after injection. Biliary tract levels generally run parallel to serum levels but were about 15 times higher than those. Peak levels in T-tube bile averaged 1137 mg/l 60 to 90 min after administration. 12 hours after administration there were still mean concentrations of 13 mg/l to be found. It is concluded that azlocillin concentrations in bile exceed for a long time the minimum inhibitory concentrations for gram-negative and gram-positive causative organisms (above all E. coli, enterococci, Klebsiella spp., Proteus spp., staphylococci) of biliary tract-infections.

Bile↗
PubMed1979

Comparative study of the binding of acylureidopenicillins and carbenicillin to human serum proteins.

The binding of the acylureidopenicillins azlocillin and mezlocillin to serum proteins was investigated by means of equilibrium dialysis and ultracentrifugation. The penicillin concentrations were determined by the agar diffusion test and by circular dichroism. The degree of binding is dependent on the penicillin concentration. At a mean penicillin concentration of 20 microgram/ml 39% of azlocillin is bound by serum proteins and 35% of mezlocillin. The acylureidopenicillins are bound to about the same degree by the two proteins albumin and gamma globulin, which occur in different concentrations in serum. The binding affinity delta F degree for the interaction between azlocillin and mezlocillin to human albumin is equal to -15,389 J/mol. The corresponding values for the binding of ampicillin and carbenicillin are -17,340 and -16,800 J/mol. Albumin has one binding site of a high affinity and two binding sites of a low affinity for the acylureidopenicillins. Measurements of partition coefficients of the penicillins for isobutanol and aqueous solution show that the interaction between acylureidopenicillins and serum is mainly hydrophobic in nature. This can be deduced from the fact that for example in the presence of sisomicin azlocillin is not displaced from its albumin binding site, in contrast to carbenicillin. The reason for this difference in behaviour lies in the fact that carbenicillin, like sisomicin, is bound to the serum proteins mainly by ionic bonds. In the case of azlocillin, however, hydrophobic bounds predominate which are not influenced by the ionic bonds of sisomicin.

Blood Proteins↗
PubMed1977

[Concentrations in serum and tonsils after infection of azidocillin (author's transl)].

Prior to tonsillectomy 57 selected patients were given 1 g azidocillin i.v. in the form of a 10% aqueous solution. Serum samples were drawn at different times after the injection and both the serum and the tonsils were examined for azidocillin activity. The results of examination of 133 serum samples and 111 tonsils were evaluated, in addition to 74 paired values for tonsils and serum. Serum levels attained a maximum of 230 microng/ml and remained within measurable range for at least six hours. Tonsil levels reached a maximum of 17 microng/g and after three hours began to drop below measurable range. The quotient for distribution between tonsils and serum rose during the first hour to 20-25% (average approx. 10%) and was about 3-6% three to four hours after injection.

Adult↗