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Biomedical subjects

S W Zimmerman

Publications and source records attributed to S W Zimmerman.

At least 19 recordsLinked to original sources
PubMed1992

Single-dose pharmacokinetics of piperacillin and tazobactam in patients with renal disease.

Tazobactam is an irreversible inhibitor of many beta-lactamases. In combination with piperacillin, tazobactam exhibits synergy against many beta-lactamase-producing bacteria. The pharmacokinetics of piperacillin and tazobactam were evaluated in eight normal volunteers and in 52 patients with renal dysfunction. Plasma and urine were obtained for up to 30 hours after an infusion of piperacillin and tazobactam (3 and 0.375 gm, respectively). Dialysate samples were collected from patients undergoing dialysis. Piperacillin and tazobactam concentrations were determined by high-performance liquid chromatography. Noncompartmental methods were used for pharmacokinetic analysis. Piperacillin and tazobactam total body clearance, area under the curve, and terminal elimination rate correlated with renal function. Hemodialysis removed 31% and 39% of piperacillin and tazobactam, respectively. During continuous ambulatory peritoneal dialysis, 5.5% of the piperacillin and 10.7% of the tazobactam was recovered in the dialysate over 28 hours. Peak plasma concentrations of both drugs increased minimally with decreasing creatinine clearance. Dosage alterations for creatinine clearance values less than 40 ml/min are recommended.

Adult↗
PubMed1992

A prospective open-label study evaluating the efficacy and adverse reactions of the use of Niferex-150 in ESRD patients receiving EPOGEN.

Iron supplementation is usually required in patients receiving epoetin alfa. Ferrous sulfate is commonly prescribed, however many patients experience adverse gastrointestinal effects. Adverse effects may limit the amount of iron that can be prescribed, and may lead to noncompliance. Polysaccharide-iron complex (PIC) is an iron supplement containing greater amounts of elemental iron, and may produce fewer adverse effects. This study compared the efficacy and adverse effects of PIC to a historical period of treatment with ferrous iron salts to 38 dialysis patients receiving epoetin alfa. All patients were switched to PIC, and were followed for six months. The following laboratory information was recorded: hematocrit, serum iron concentration, percent transferrin saturation, total iron-binding capacity, serum ferritin concentration. Patients were given an adverse experience questionnaire at four and six months of PIC treatment. No differences in laboratory values were noted between treatments. The amount of prescribed elemental iron increased, while iron dextran use decreased during PIC therapy. Epoetin alfa doses were unchanged. Patients reported fewer gastrointestinal adverse effects at four months, however differences at six months were less striking. PIC is as effective as ferrous sulfate in sustaining erythropoiesis in patients receiving epoetin alfa. It may produce fewer adverse effects.

Administration, Oral↗
PubMed1991

Randomized controlled trial of prophylactic rifampin for peritoneal dialysis-related infections.

Staphylococcal infections are a major cause of catheter infections and peritonitis in peritoneal dialysis patients. Since catheter-related infections are associated with nasal carriage of Staphylococcus aureus in this population, we studied the effect of intermittent rifampin, an antibiotic known to decrease S aureus nasal carriage, on catheter-related infections and peritonitis. We randomly assigned 64 patients to receive either rifampin 300 mg twice daily for 5 days every 3 months or no treatment. The rifampin-treated patients had a significant delay in time to first catheter-related infection (P less than 0.015) and significantly fewer catheter-related infections overall (P less than 0.001). The catheter-related infection rate in rifampin-treated patients was .26 per patient-year versus .93 per patient-year in untreated patients. Multivariate analysis defined baseline colonization of nares or catheter exit-site and prior renal transplant as risk factors for catheter-related infections. There was no significant difference in peritonitis rates between groups, although the trend was for a delayed time to first episodes and fewer episodes in rifampin-treated patients. Adverse effects necessitated withdrawal of rifampin in four patients. We conclude that intermittent rifampin administration is effective in decreasing catheter-related infections in a peritoneal dialysis population.

Adult↗
PubMed1991

Erythropoietin use in peritoneal dialysis patients.

Erythropoietin (Epo) is currently used less extensively in peritoneal dialysis (PD) patients than in hemodialysis (HD) patients. Early data suggest that Epo is equally effective in PD patients, and that the risk profile is similar. No adverse consequences to the dialysis procedure or peritonitis rates have been consistently noted. It has been suggested that PD patients may require less Epo than their HD counterparts, but this is unproven. Further research on the preferred route of administration and timing of the dosing is necessary.

Anemia↗
PubMed1990

Ampicillin and sulbactam pharmacokinetics and pharmacodynamics in continuous ambulatory peritoneal dialysis (CAPD).

The fixed combination antibiotic ampicillin/sulbactam may provide a new, safe, and effective method of treating dialysis-related bacterial peritonitis. The pharmacokinetics of this antibiotic combination were determined in patients receiving continuous ambulatory peritoneal dialysis (CAPD). The pharmacodynamic activity of this drug was also determined by use of mean bactericidal titers against selected bacterial strains. Six noninfected CAPD patients in a randomized two-way crossover study were given a fixed dose of ampicillin (2 gm) and sulbactam (1 gm) either intravenously or intraperitoneally. The mean peak ampicillin and sulbactam serum concentrations following intravenous dosing were 170.3 and 87.5 micrograms/mL, respectively. The mean peak serum concentrations of ampicillin and sulbactam following intraperitoneal dosing were 48.0 and 27.8 micrograms/mL, respectively. Absolute bioavailabilities of the intraperitoneal ampicillin and sulbactam doses were 60% and 68%. Both drugs exhibited similar distribution and elimination characteristics. Renal failure markedly reduced drug elimination. Intraperitoneal administration of ampicillin/sulbactam provided satisfactory inhibitory and bactericidal antibiotic titers for most organisms in dialysate at 6 h but not 24 h. Ampicillin/sulbactam (2 gm/1 gm) should be administered every 12 h to patients with peritoneal dialysis-related peritonitis.

Adult↗
PubMed1989

Intraperitoneal Vancoled does not cause chemical peritonitis.

A prior report has suggested that loading doses of intraperitoneal Vancoled (vancomycin, Lederle) cause chemical peritonitis in patients with catheter infections. The present open-label study was conducted to determine the effects of a 30 mg/kg intraperitoneal loading dose of Vancoled given to five patients with a culture-positive, erythematous, draining exit-site infection. Prior to dosing, all dialysate was drained and sent for baseline cell count and culture. The loading dose was added to the dialysate and infused in the usual fashion. A sample of dialysate was drained at two hours and sent for cell count and culture. The entire exchange was drained at four hours and also sent for cell count and culture. Serum vancomycin concentrations wer measured at four hours. Baseline dialysate contained less than 9 white blood cells per microliter in all patients. Two and four hour samples contained less than 4 and less than 11 white blood cells per microliter, respectively. All fluid was sterile. WB C differential counts were unremarkable. No adverse effects occurred. The mean serum vancomycin concentration was 26.5 micrograms/ml. Intraperitoneal Vancoled did not cause chemical peritonitis and was well-tolerated by patients with exit-site infections.

Adult↗
PubMed1988

Pharmacokinetics and pharmacodynamics of cefoperazone-sulbactam in patients on continuous ambulatory peritoneal dialysis.

This study was conducted to determine the pharmacokinetics of the fixed combination antibiotic cefoperazone-sulbactam in patients receiving continuous ambulatory peritoneal dialysis (CAPD). In addition, the pharmacodynamic profile of this combination was determined by the use of mean bactericidal titers against selected bacterial strains. Six noninfected CAPD patients were given a fixed dose of cefoperazone (2 g) and sulbactam (1 g) either intravenously or intraperitoneally over 10 min in a randomized, two-way crossover fashion. The mean peak cefoperazone concentration in serum after intravenous administration was 280.9 micrograms/ml. The mean peak concentration in serum after intraperitoneal cefoperazone administration was 38.9 micrograms/ml and occurred 2 to 4 h postdose. The mean peak sulbactam concentration in serum after intravenous administration was 82.2 micrograms/ml. The mean peak concentration in serum after intraperitoneal sulbactam administration was 24.4 micrograms/ml and occurred at 6 h. The absolute bioavailability of the intraperitoneal dose was 61% for cefoperazone and 70% for sulbactam. Cefoperazone total body and renal clearances were unaffected by renal failure and dialysis. However, both clearance values for sulbactam were reduced markedly. Only intraperitoneal dosing provided peak inhibitory and bactericidal titers in dialysate for all organisms tested. Intravenous dosing provided satisfactory dialysate titers only for very susceptible bacterial strains. End-stage renal disease and CAPD do not alter cefoperazone pharmacokinetics; however, sulbactam dosing may need to be adjusted.

Adult↗
PubMed1987

Long-term survivors on peritoneal dialysis.

To obtain information about predialysis characteristics and long-term outcome of patients on peritoneal dialysis (PD) for more than 4 years, we reviewed all patients starting PD who performed continuous ambulatory peritoneal dialysis (CAPD) and were at risk for more than 4 years. Sixty-two patients started; 42% were diabetic and 35% over age 60. Three recovered renal function, seven received transplants, and 12 switched to hemodialysis. Nineteen survived more than 4 years (long-term survivors, LTS), eight diabetic and 12 male. Twenty-one died on CAPD in less than 4 years (short-term survivors, STS). In comparison to STS, LTS were younger, with less prior cardiac disease, yet had higher predialysis serum creatinine values and lower hematocrits. LTS were observed for a mean of 65.3 +/- 3 months (48 to 91 months), and STS for a mean of 21 +/- 2 months. When compared to STS, LTS had fewer hospital days, hospital days for peritonitis, and a lower peritonitis rate, although the incidence of Staphylococcus aureus peritonitis was greater in LTS. Cardiovascular and thromboembolic events were less frequent in LTS, but bone fractures were seen more often in the LTS diabetic patients. Weight gain, especially in males, and hernias were noted in both groups. BP improved, and vision was maintained in both groups. Non-PD-related infections causing hospitalization were low in both groups. Improved mean hematocrit and hemoglobin A, values were seen only in LTS. Mean serum cholesterol values increased with time in LTS. This study reveals that potentially high-risk patients such as diabetics and the elderly can have prolonged survival on PD.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Exercise tolerance changes following renal transplantation.

Maximal exercise capacity was measured in 20 nondiabetic patients with end-stage renal disease before and soon after successful renal transplantation. Maximal oxygen consumption increased significantly in all patients posttransplant. Increases in maximal heart rate and heart rates at 70% of maximal levels were also observed. The changes in maximal oxygen consumption were not significantly correlated with changes in hematocrit. The removal of uremia may result in improved functioning of one or more of the systems involved in oxygen transport and utilization that determine exercise capacity.

Adrenergic beta-Antagonists↗
PubMed1986

Exercise in end-stage renal disease.

Available studies indicate that exercise tolerance in renal patients is low. Although significant improvements in maximal oxygen consumption have been reported following exercise training in these patients, there may be physiologic limitations to the attainable levels of aerobic capacity due to the multisystemic nature of the disease. Long-term exercise training may result in other medical benefits. Compliance to regular exercise in hemodialysis patients remains a problem, however, exercise training during the dialysis treatment may prove beneficial in terms of compliance and supervision.

Adolescent↗
PubMed1986

Exercise capacity in hemodialysis, CAPD, and renal transplant patients.

Eighteen hemodialysis, 12 chronic ambulatory peritoneal dialysis (CAPD), and 20 renal transplant patients performed maximal treadmill exercise tests. Heart rates and blood pressures were determined every minute and maximal oxygen consumption was measured directly. Exercise capacity as measured by VO2 max is low in dialysis patients and similar to sedentary normal individuals in renal transplant patients. Maximal heart rates were significantly lower in hemodialysis patients than transplant recipients. The lower exercise tolerance in end-stage renal disease indicates that most patients regardless of the treatment mode could benefit from attempts through exercise training to increase physical working capacity.

Adult↗
PubMed1985

Vancomycin disposition during continuous ambulatory peritoneal dialysis: a pharmacokinetic analysis of peritoneal drug transport.

Expressions are presented to describe the absorption and also clearance of drugs administered into the peritoneal cavity of patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Application of the expressions to vancomycin kinetics in five male CAPD patients showed that therapeutic levels of vancomycin can readily be achieved and maintained in the systemic circulation by administering the appropriate loading and maintenance doses. The intrinsic peritoneal clearance of vancomycin reported here is higher than the apparent clearances reported previously, averaging 300 to 500 ml/min under the conditions used in this study. The low apparent clearances previously reported are useful clinically although they do not represent the true efficiency of vancomycin removal by CAPD. The degree to which apparent clearance underestimates the true intrinsic clearance is exponentially related to the dwell time of dialysate in the peritoneum. Intraperitoneal administration is a practical alternative to other routes for CAPD patients needing antibiotic or other therapy.

Adult↗
PubMed1985

Plasmapheresis and dipyridamole for recurrent focal glomerular sclerosis.

A 38-year-old man had recurrence of nephrotic syndrome with focal glomerular sclerosis (FGS) in two consecutive cadaveric renal allografts. His first graft was lost to recurrent disease after 30 months. Because prior animal experiments performed when he had his first graft indicated a possible serum factor or factors capable of enhancing urine protein excretion, three plasmapheresis periods of 6-8 treatments each were performed 3, 23 and 34 months after recurrence of FGS in the second graft. Urine protein excretion was decreased transiently in the first treatment period when the allograft biopsy revealed only glomerular foot process effacement. The second and third plasmapheresis treatment periods were performed after typical lesions of FGS were present in the graft and moderate renal insufficiency occurred. Dipyridamole was also given at this time. There has been associated stabilization of renal function for over 31 months. Prior to this, renal function was significantly (p less than 0.001) decreasing with time. The reasons for stabilization of renal function in this man with recurrent FGS are not defined, but the results suggest the need to further evaluate plasmapheresis and the platelet inhibitor dipyridamole in native and recurrent FGS.

Adult↗
PubMed1985

Pharmacokinetics of intravenous ceftizoxime in patients on continuous ambulatory peritoneal dialysis.

The pharmacokinetics of ceftizoxime (CZM) were determined in 16 non-infected CAPD patients. Patients received either 500 mg or 1000 mg CZM by i.v. bolus. The dialysate exchange volume was 2 l. Serum CZM concentrations at 10 min were 69.7 +/- 19.7 micrograms/ml (1000 mg dose) and 39.2 +/- 8.4 micrograms/ml (500 mg dose), and declined to 33.7 +/- 13.9 micrograms/ml and 16.9 +/- 3.2 micrograms/ml respectively at 360 min. Dialysate CZM levels at 10 and 360 min were 1.8 +/- 1.3 and 19.9 +/- 6.6 micrograms/ml respectively (1000 mg dose) and 1.4 +/- 0.9 and 12.6 +/- 3.5 micrograms/ml (500 mg dose). The half-time of CZM was 14.1 +/- 4.6 h. Peritoneal clearance of CZM was low and equilibrium was not achieved in 6 h. However peritoneal CZM concentrations were adequate within 1 h for the treatment of most organisms which cause CAPD-related peritonitis.

Adult↗
PubMed1979

Exertional heatstroke in novice runners.

Heatstroke occurred in four apparently normal but inexperienced runners who were involved in road races of 10, 16, 32, and 42 km. Each of the runners attempted to increase his running pace by approximately 1 min/km during the last 5 km of the race. Symptoms of heatstroke occurred within five to ten minutes of the onset of increased effort. In three cases, environmental conditions (temperatures, 24 to 26 degrees C) were contributory. Specific guidelines and instructions are needed for inexperienced runners who enter distance road races.

Adult↗