Effect of Erythropoietin in Continuous Ambulatory Peritoneal Dialysis Patients: Comparison between Intravenous and Intraperitoneal Administration

The administration of recombinant human erythropoietin (rHuEPO) in CAPD patients is usually done subcutaneously. Only a few authors have reported on its intraperitoneal (IP) administration. We compared the effect of IP administration of rHuEPO in CAPD patients to that of intravenous (IV) administration. Ten anemic CAPD patients injected rHuEPO into their dialysis bag once a day, 3 times a week, for 18 weeks. The initial dose was 12000 U. The dwell time of the exchanges with rHuEPO was about 6 hours. Nineotheranemic CAPD patients were treated with IV rHuEPO once a week for 18 weeks. The initial dose was 6000 U. In the IP group the hematocrit rose from 24.04±2.7% to 33.3±3.8% (mean±SD). In the IV group 2 patients were excluded from the efficiency evaluation. In 7 of the 9 patients in the IV group, the hematocrit rose from 23.27±2.6% to 32±5.5% (mean±SD).

The intraperitoneal administration of rHuEPO in CAPD patients is sufficient in improving anemia, although it requires a much larger dosage to yield the same level of improvement as the one obtained with the intravenous administration. However, in patients on continuous cycling peritoneal dialysis or IP dialysis, a smaller dosage during the prolonged dwell time may be effective.

The Pharmacokinetics of Intraperitoneal Erythropoietin Administered Undiluted Or Diluted in Dialysate

+ Objective

To compare the bioavailability of intraperitoneal erythropoietin (EPO) administered undiluted versus diluted in 2 L of dialysis fluid.

+ Design

Group 1 patients received one dose of EPO, 400 Ulkg BW given with vehicle only. This dwelled for 8 hours after which 2 L of dialysate were infused. Group 2 patients received the same dose of EPO diluted in 2 L of dialysate which dwelled for 8 hours. Both groups resumed their CAPD regimen after the first 8 hours. Blood levels of EPO were measured for 24 hours in both groups.

+Setting

The Home Peritoneal Dialysis Unit, Toronto Hospital, Western Division.

+ Patients

The participants were on CAPD for at least three months, free of peritonitis, and had no abnormalities of peritoneal transport. Three patients took part in both arms of the study, and there were 6 patients altogether in each group.

+ Results

When EPO was administered undiluted, there was a greater than ninefold increase in bioavailability of the hormone as measured by the area under the curve (AUC), compared to when the same dose was diluted in 2 L of dialysis fluid.

+ Conclusions

The previous studies that reported low bioavailability of intraperitoneal EPO used the hormone diluted in dialysate. The current findings suggest that if EPO is given in the dry peritoneal cavity, the bioavailability is greatly improved and may be clinically effective. Intraperitoneal instillation may prove to be an alternative route for EPO in the peritoneal dialysis patient unable or unwilling to receive subcutaneous injections. We are currently studying the effectiveness of undiluted intraperitoneal EPO in CAPD patients.

Insulin Stimulates the Activity of Na+/K+-Atpase in Human Peritoneal Mesothelial Cells

Objective

To assess the effect of insulin on the Na+/ K+-ATPase expression and activity in human peritoneal mesothelial cells (HPMC).

Methods

HPMC were isolated from the omental tissue of non-uremic patients, grown to confluence and rendered quiescent by serum deprivation for 24 hours. The activity of Na+/K+-ATPase was determined by measuring the ouabain-sensitive86Rb uptake. To assess whether the effect of insulin was related to changes in [Na+]i the sodium influx was measured with 22Na and the activity of Na+/K+ -A TPase was assessed in the presence of amiloride. Expression of Na+/K+ -A TPaseα1’ α2 and β1-subunit mRNAs was determined by RT/PCR.

Results

Exposure of HPMC to insulin resulted in a time and dose-dependent increase in the Na+/K+-ATPase activity. After 60 minutes the ouabain-sensitive 86Rb up take (cpm/104 cells) was increased from 6650±796 in control cells to 9763±1212 in HPMC exposed to 100 mU/ mL insulin (1.5-fold increase; n=4, P<0.05). In addition, incubation of HPMC with 100 mU/mL insulin resulted in a time-dependent increase in the 22Na influx. Pre-exposure of HPMC to 1 mM amiloride reduced the activity of Na+/K+-A TPase but did not block the stimulatory effect of insulin. RT/PCR analysis revealed that HPMC constitutively expressed α1 and β1-subunit mRNAs while the α2-subunit mRNA was barely detectable. Exposure of HPMC to insulin for up to 24 hours was not associated with any changes in the expression of either α1’ α2 or B1-subunit.

Conclusion

Insulin stimulates the Na+/K+-ATPase activity in HPMC in a time and dose-dependent manner. This effect appears to mediated by an increase in [Na+]i and is not related to alterations in Na+/K+-ATPase subunit mRNAs expression.

Intraperitoneal Administration of Recombinant Human Erythropoietin in Uremic Animals

Previous protocols of administration of recombinant human erythropoietin to patients with end-stage renal disease have been by the i.v. route. Because this method would be impractical for the continuous ambulatory peritoneal dialysis patient, we designed an i.p. dosing protocol in uremic rabbits to examine whether significant amounts of this hormone could be absorbed from the peritoneal cavity. Our results demonstrate that almost all of the erythropoietin is absorbed (or adsorbed) during a prolonged dwell when administered undiluted by dialysate.

Three diabetic peritoneal dialysis patients receiving intraperitoneal insulin with dosage adjustment based on capillary glucose levels during peritoneal equilibrium tests

Diabetic patients receiving peritoneal dialysis have vast differences in glucose absorption, significantly affecting glycemic control. Measurement of glucose levels between dialysate exchanges does not adequately reflect these changes. By measuring glucose levels during the peak period of glucose absorption, as determined by a peritoneal equilibrium test, such differences can be measured and accounted for when determining doses of intraperitoneal insulin. In this report, 3 cases in which such an approach was applied are described.

Renal replacement therapies in the elderly: Part 1. Hemodialysis and chronic peritoneal dialysis

Recent demographic data from the United States and Europe demonstrate that the dialysis population is growing progressively older. In the United States the median age at onset of end-stage renal disease (ESRD) had reached 61 years in 1990, and the fraction of ESRD patients older than 65 years will approach 60% by the year 2000. The primary treatment of geriatric ESRD is center hemodialysis (82% of elderly patients). Chronic peritoneal dialysis in this age group is limited in the United States to less than 10%. Only 2.7% of elderly patients have a functioning transplant. Despite their complex medical and psychosocial conditions, survival and rehabilitation are acceptable in the elderly dialysis patient and these patients tend to be more complaint. Five-year dialysis patient survival rates in the United States are 19% and 10%, respectively, for the 65 to 74 and 75 to 84 age groups compared with 32% and 19%, respectively, for the same age groups in Europe. Five-year survival, particularly in the elderly, is even higher in Japan. Several factors favor the delivery of low doses of hemodialysis in the elderly and discontinuing dialysis is more common in the elderly. Continuous ambulatory peritoneal dialysis is a satisfactory alternative treatment modality for geriatric ESRD. Most studies confirm that survival of elderly patients on continuous ambulatory peritoneal dialysis and hemodialysis is similar. The 1991 United States Renal Data System report showing higher mortality among diabetic continuous ambulatory peritoneal dialysis patients than among hemodialysis patients may reflect selection of such patients, who may have more co-morbid conditions. In special cases, continuous cyclic peritoneal dialysis can be an alternative treatment for elderly ESRD patients.