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B Bannwarth

Publications and source records attributed to B Bannwarth.

At least 91 records · Page 5Linked to original sources
PubMed1994

Column-switching high-performance liquid chromatographic determination of vancomycin in serum.

Concentrations of vancomycin in serum were measured by an automatic high-performance liquid chromatographic (HPLC) micromethod. Vancomycin is a glycopeptide antibiotic with broad application in the therapy of gram-positive infections. As this drug is potentially nephro- and ototoxic, a method to maximize its therapeutic benefit while minimizing the risk of toxicity is desirable. This fully automated HPLC method did not involve a sample pretreatment step. The configuration of the apparatus permitted a solid phase extraction of the serum sample on two precolumns filled with a reversed-phase material, followed by a chromatographic separation of the sample constituents on an analytical column. The reversed phase analytical column (muBondapak C18) was flushed with a mobile phase of water-acetonitrile-triethylamine, 870: 130: 4 (vol/vol/vol); the pH was adjusted to 3.0 with orthophosphoric acid. Precision was expressed as the coefficient of variation (CV), which was always < or = 4.13% for intra- and inter-assays (n = 10) in the range 2-50 micrograms/ml. We compared this specific HPLC determination to an enzyme-multiplied immunoassay (EMIT). Fifty clinical samples obtained from patients under vancomycin therapy were assayed by each method and results compared using a linear regression analysis. There was a significant correlation between results from HPLC and EMIT: EMIT = 0.51 + 1 x HPLC (r = 0.963; p < 0.0001). The rapidity and specificity of this HPLC micromethod make it suitable for use in the monitoring of serum levels of vancomycin and for use in pharmacokinetic studies of this antibiotic.

Autoanalysis↗
PubMed1994

Cefpiramide kinetics and plasma protein binding in cholestasis.

Cefpiramide is a new parenteral cephalosporin mainly excreted in the bile. Eight patients with cholestasis and 11 healthy subjects received a single 1 g i.v. dose. Cefpiramide concentrations in plasma and urine were measured by h.p.l.c. and plasma binding was determined by ultrafiltration. Total clearance of cefpiramide (mean +/- s.d.) was 15.5 +/- 7.1 ml min-1 in patients and 25.6 +/- 4.6 ml min-1 in healthy subjects. As a result, the terminal elimination half-life was longer in patients (12.0 +/- 2.9 h vs 5.3 +/- 0.9 h). Owing to impaired biliary elimination of cefpiramide in cholestasis, the urinary recovery of unchanged drug in patients was about five times greater than in healthy subjects (85.1 +/- 10.3% vs 16.2 +/- 3.9%). Plasma binding was significantly lower in cholestasis (fu = 0.23 +/- 0.13 vs 0.02 +/- 0.004 in healthy subjects). Accordingly, the dosage regimen of cefpiramide should be modified in patients with cholestasis.

Aged↗
PubMed1994

Influence of food and body weight on the pharmacokinetics of penticainide.

The pharmacokinetics of penticainide, a class Ic antiarrhythmic drug, was studied in 16 healthy adults (eight males and eight females) after a single 300-mg oral dose in fasting conditions and with a standard meal. Penticainide concentrations in plasma and urine were measured by hplc. The pharmacokinetic parameters of penticainide including Cmax, tmax, AUC and t1/2 were not significantly altered in the presence of food. AUC values (mean +/- sd) were 50.68 +/- 10.8 mg.h.l-1 and 49.52 +/- 9.87 mg.h.l-1 in the absence and presence of food, respectively. However, a significant difference was observed between males and females in both fasting and fed conditions with a higher value of the apparent oral clearance in the second group. The values of apparent oral clearance, expressed in weight-normalized units were 1.33 +/- 0.35 ml.mn-1.kg-1 (male) and 1.93 +/- 0.34 ml.mn-1.kg-1 (female) in fast conditions (P < 0.01) and 1.38 +/- 0.28 ml.mn-1.kg-1 (male) and 1.93 +/- 0.49 ml.mn-1.kg-1 (female) in fed conditions (P < 0.02), respectively. The pharmacokinetics of penticainide is not modified by the presence of food, but an influence of body weight may be considered.

Adult↗
PubMed1994

Methotrexate in rheumatoid arthritis. An update.

Methotrexate has been approved for the treatment of refractory rheumatoid arthritis by several regulatory agencies, including the Food and Drug Administration. The tendency is now to prescribe it at earlier stages of the disease. Methotrexate is a well known antifolate. Its exact mechanism of action in rheumatoid arthritis remains uncertain. The polyglutamated derivatives of methotrexate are potent inhibitors of various enzymes, including dihydrofolate reductase and 5-aminoimidazole-4-carboxamide ribonucleotide transformylase. Inhibitory effects on cytokines, particularly interleukin-1, and on arachidonic acid metabolism, as well as effects on proteolytic enzymes, have been reported. Some of them may be linked to the antifolate properties of methotrexate. Overall, the drug appears to act in rheumatoid arthritis as an anti-inflammatory agent with subtle immunomodulating properties. Direct inhibitory effects on rapidly proliferating cells in the synovium have also been suggested. Methotrexate is usually given orally. Marked interindividual variation in its bioavailability has been found. Food intake has no significant effect on the pharmacokinetics of oral methotrexate. Methotrexate undergoes significant metabolism. The functionally important metabolites are the polyglutamated derivatives of methotrexate, which are selectively retained in the cells. Less than 10% of a dose of methotrexate is oxidised to 7-hydroxy-methotrexate, irrespective of the route of administration. This metabolite is extensively (91 to 93%) bound to plasma proteins, in contrast to the parent drug (35 to 50% bound). Methotrexate is mainly excreted by the kidneys. It undergoes tubular secretion and may thereby compete with various organic acid compounds. Early placebo-controlled trials demonstrated that weekly low dosage methotrexate produced early symptomatic improvement in most rheumatoid arthritis patients. Two meta-analyses showed that methotrexate is among the most efficacious of slow-acting antirheumatic agents, together with parenteral gold (sodium aurothiomalate), penicillamine and sulfasalazine. Furthermore, in the short term context of clinical trials, methotrexate has one of the best efficacy/toxicity ratios. There is little evidence that methotrexate, or any available slow-acting antirheumatic agent, is a true disease-modifying drug. However, the probability that a patient will continue methotrexate therapy over time appears quite favourable compared with any other slow-acting antirheumatic drug. Combination therapy with slow-acting drugs has been advised for the management of rheumatoid arthritis, but the evidence currently available does not support general use of combination therapy including methotrexate. Almost all investigations indicated that toxic effects, rather than lack of response, were the major reason for discontinuing methotrexate therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

[Side-effects during treatment of rheumatoid arthritis with methotrexate].

Methotrexate is the drug with the highest long-term continuation rate in rheumatoid arthritis patients. However, toxicity is the main reason for methotrexate withdrawal. Most adverse effects are mild abnormalities, such as digestive symptoms, stomatitis, elevations in transaminase levels, and moderate decreases in peripheral blood cell counts. Potentially life-threatening effects include hypersensitivity pneumonitis and pancytopenia. Cirrhosis is less common than in patients with psoriasis. Opportunistic infections and Epstein-Barr virus-related lymphomas have been reported. Neurological disorders, cutaneous reactions and renal lesions have been ascribed to low-dose methotrexate. Prior renal dysfunction and concomitant administration of a number of drugs, including cotrimoxazole, have been shown to increase methotrexate toxicity. However, susceptibility to the toxic effects of methotrexate varies widely across individuals. The effectiveness of folate supplementation in preventing methotrexate toxicity remains controversial.

Arthritis, Rheumatoid↗
PubMed1993

Pharmacokinetics of intravenous and intraperitoneal ceftazidime in chronic ambulatory peritoneal dialysis.

The pharmacokinetics of ceftazidime have been investigated in eight patients with chronic renal failure undergoing continuous ambulatory peritoneal dialysis. Each subject was given ceftazidime 1 g intravenously and 1 g intraperitoneally at an interval of 1 week. Ceftazidime was assayed by high-pressure liquid chromatography. After intravenous administration, the pharmacokinetic parameters of ceftazidime were: elimination plasma half-life (t1/2 beta) = 24.6 +/- 4.6 hours; apparent volume of distribution (V(area)): 0.37 +/- 0.09 1/kg, total plasma clearance (CL): 11.9 +/- 3.3 mL/minute, peritoneal clearance (CLp): 1.7 +/- 0.3 mL/minute. Over 72 hours, only 15.6 +/- 4.7% of the dose was eliminated by the peritoneal route. After intraperitoneal administration, ceftazidime appeared in the plasma rapidly, and the peak plasma concentration of 24.5 +/- 5.2 mg/L was achieved at the fourth hour; the elimination half-life (t1/2ke) was 20.8 +/- 1.7 hours. The absorption of ceftazidime from the peritoneal space was 74.1 +/- 7.4%. These data suggest that ceftazidime has bidirectional exchange characteristics through the peritoneal membrane. A single 1-g intraperitoneal dose led to serum and dialysate concentrations of ceftazidime above the minimum concentrations for susceptible pathogen germs for 24 hours.

Adult↗
PubMed1993

The determination of bromazepam in plasma by reversed-phase high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method has been developed for the determination of bromazepam, an anxiolytic benzodiazepine, in plasma. After a single-step extraction from alkalinized plasma with diethyl-ether in the presence of an internal standard (alpha-hydroxy-triazolam), the residues were chromatographed on a reversed-phase Nova Pak 5 microns C18 column, with a mobile phase of acetonitrile-water-triethylamine (700:300:4, v/v/v) adjusted to pH 7.4 with orthophosphoric acid. The limit of detection was 50 ng ml-1, using a 20 microliters injection with UV detection at 240 nm. Between-day and within-day relative standard deviations were lower than 6%. Studies of drug stability during sample storage at -20 degrees C and at +4 degrees C showed no degradation of bromazepam. However, bromazepam seemed to be degraded at ambient temperature, without any influence of light. This method is applied to the determination of bromazepam plasma levels in analytical toxicology.

Benzodiazepines↗
PubMed1993

Effect of famotidine on renal transplant patients treated with ciclosporine A.

The influence of a 7-day course of 40 mg famotidine administered orally on the pharmacokinetics of ciclosporine A at steady-state has been investigated in 10 renal transplant patients. Famotidine did not appear to significantly alter the pharmacokinetics of ciclosporine A. This might be ascribed to the limited potential of famotidine for inhibiting microsomal enzyme function. Moreover, plasma creatinine concentrations and creatinine clearance remained stable. Our results suggest that famotidine has no noticeable interaction with ciclosporine A.

Adult↗
PubMed1993

[Tissue and systemic diffusion of idrocilamide after cutaneous administration].

Experimental findings have demonstrated that idrocilamide exhibits antiinflammatory and muscle relaxant properties due at least in part to tissular effects. Percutaneous diffusion of a 10% glycero-alcoholic idrocilamide solution was studied in ten patients scheduled to undergo total knee replacement. Four 200-mg doses of idrocilamide were applied to the suprapatellar area at 12-hour intervals before surgery. Pain was evaluated using a visual analog scale before and after treatment. Surgery was performed 1.75 to 3.5 hours after the last idrocilamide dose. Idrocilamide was assayed using high performance liquid chromatography in tissue, plasma, and joint fluid specimens taken during the surgical procedure. Topical administration of idrocilamide on healthy skin produced significant concentrations of the drug in all the tissue specimens, including subcutaneous fat, muscle, tendon, synovium, and knee capsule. Tissue levels were consistently higher than synovial fluid and plasma levels, indicating that little systemic diffusion occurred. Idrocilamide levels in potential target tissues might influence clinical effects.

Administration, Cutaneous↗
PubMed1993

Pharmacokinetics and pharmacodynamics of non steroidal anti-inflammatory drugs in synovial fluid.

Since the joint is the target organ of non steroidal anti-inflammatory drugs (NSAIDs) in rheumatic diseases, the concentration in the synovial fluid (SF) is an important determinant of clinical response to these agents. Present data indicate that in the SF pharmacokinetic behaviour of NSAIDs depends on their plasma elimination half-life. Moreover, some chiral drugs exhibit stereoselective distribution properties. Finally, pharmacodynamic investigations suggest that inhibition of prostaglandin synthesis in the synovial compartment is the dominant mechanism of action for most, if not all, NSAIDs.

Anti-Inflammatory Agents, Non-Steroidal↗