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Procrit

"The U.S. Food and Drug Administration approved a risk management program to inform healthcare providers and their patients about the risks of a class of drugs called Erythropoiesis-Stimulating Agents (ESAs). For patients with cancer, the program "...

Procrit

Procrit

CLINICAL PHARMACOLOGY

Chronic Renal Failure Patients

Endogenous production of erythropoietin is normally regulated by the level of tissue oxygenation. Hypoxia and anemia generally increase the production of erythropoietin, which in turn stimulates erythropoiesis.2 In normal subjects, plasma erythropoietin levels range from 0.01 to 0.03 Units/mL and increase up to 100- to 1000-fold during hypoxia or anemia.2 In contrast, in patients with chronic renal failure (CRF), production of erythropoietin is impaired, and this erythropoietin deficiency is the primary cause of their anemia.3,4

Chronic renal failure is the clinical situation in which there is a progressive and usually irreversible decline in kidney function. Such patients may manifest the sequelae of renal dysfunction, including anemia, but do not necessarily require regular dialysis. Patients with end-stage renal disease (ESRD) are those patients with CRF who require regular dialysis or kidney transplantation for survival.

PROCRIT® (epoetin alfa) has been shown to stimulate erythropoiesis in anemic patients with CRF, including both patients on dialysis and those who do not require regular dialysis.4-12 The first evidence of a response to the three times weekly (TIW) administration of PROCRIT® (epoetin alfa) is an increase in the reticulocyte count within 10 days, followed by increases in the red cell count, hemoglobin, and hematocrit, usually within 2 to 6 weeks.4,5 Because of the length of time required for erythropoiesis — several days for erythroid progenitors to mature and be released into the circulation — a clinically significant increase in hematocrit is usually not observed in less than 2 weeks and may require up to 6 weeks in some patients. Once the hematocrit reaches the suggested target range (30% to 36%), that level can be sustained by PROCRIT® (epoetin alfa) therapy in the absence of iron deficiency and concurrent illnesses.

The rate of hematocrit increase varies between patients and is dependent upon the dose of PROCRIT® (epoetin alfa) , within a therapeutic range of approximately 50 to 300 Units/kg TIW.4 A greater biologic response is not observed at doses exceeding 300 Units/kg TIW.6 Other factors affecting the rate and extent of response include availability of iron stores, the baseline hematocrit, and the presence of concurrent medical problems.

Zidovudine-treated HIV-infected Patients

Responsiveness to PROCRIT® (epoetin alfa) in HIV-infected patients is dependent upon the endogenous serum erythropoietin level prior to treatment. Patients with endogenous serum erythropoietin levels ≤ 500 mUnits/mL, and who are receiving a dose of zidovudine ≤ 4200 mg/week, may respond to PROCRIT® (epoetin alfa) therapy. Patients with endogenous serum erythropoietin levels > 500 mUnits/mL do not appear to respond to PROCRIT® (epoetin alfa) therapy. In a series of four clinical trials involving 255 patients, 60% to 80% of HIV-infected patients treated with zidovudine had endogenous serum erythropoietin levels ≤ 500 mUnits/mL.

Response to PROCRIT® (epoetin alfa) in zidovudine-treated HIV-infected patients is manifested by reduced transfusion requirements and increased hematocrit.

Cancer Patients on Chemotherapy

A series of clinical trials enrolled 131 anemic cancer patients who received PROCRIT® (epoetin alfa) TIW and who were receiving cyclic cisplatin- or non cisplatin-containing chemotherapy. Endogenous baseline serum erythropoietin levels varied among patients in these trials with approximately 75% (n = 83/110) having endogenous serum erythropoietin levels ≤ 132 mUnits/mL, and approximately 4% (n = 4/110) of patients having endogenous serum erythropoietin levels > 500 mUnits/mL. In general, patients with lower baseline serum erythropoietin levels responded more vigorously to PROCRIT® (epoetin alfa) than patients with higher baseline erythropoietin levels. Although no specific serum erythropoietin level can be stipulated above which patients would be unlikely to respond to PROCRIT® (epoetin alfa) therapy, treatment of patients with grossly elevated serum erythropoietin levels (eg, > 200 mUnits/mL) is not recommended.

Pharmacokinetics

In adult and pediatric patients with CRF, the elimination half-life of plasma erythropoietin after intravenously administered PROCRIT® (epoetin alfa) ranges from 4 to 13 hours.13-15 The half-life is approximately 20% longer in CRF patients than that in healthy subjects. After SC administration, peak plasma levels are achieved within 5 to 24 hours. The half-life is similar between adult patients with serum creatinine level greater than 3 and not on dialysis and those maintained on dialysis. The pharmacokinetic data indicate no apparent difference in PROCRIT® (epoetin alfa) half-life among adult patients above or below 65 years of age.

The pharmacokinetic profile of PROCRIT® (epoetin alfa) in children and adolescents appears to be similar to that of adults. Limited data are available in neonates.16 A study of 7 preterm very low birth weight neonates and 10 healthy adults given IV erythropoietin suggested that distribution volume was approximately 1.5 to 2 times higher in the preterm neonates than in the healthy adults, and clearance was approximately 3 times higher in the preterm neonates than in the healthy adults.39

The pharmacokinetics of PROCRIT® (epoetin alfa) have not been studied in HIV-infected patients.

A pharmacokinetic study comparing 150 Units/kg SC TIW to 40,000 Units SC weekly dosing regimen was conducted for 4 weeks in healthy subjects (n = 12) and for 6 weeks in anemic cancer patients (n = 32) receiving cyclic chemotherapy. There was no accumulation of serum erythropoietin after the 2 dosing regimens during the study period. The 40,000 Units weekly regimen had a higher Cmax (3- to 7-fold), longer Tmax (2- to 3-fold), higher AUC0-168h (2- to 3-fold) of erythropoietin and lower clearance (50%) than the 150 Units/kg TIW regimen. In anemic cancer patients, the average t1/2 was similar (40 hours with range of 16 to 67 hours) after both dosing regimens. After the 150 Units/kg TIW dosing, the values of Tmax and clearance are similar (13.3 ± 12.4 vs. 14.2 ± 6.7 hours, and 20.2 ± 15.9 vs. 23.6 ± 9.5 mL/h/kg) between Week 1 when patients were receiving chemotherapy (n = 14) and Week 3 when patients were not receiving chemotherapy (n = 4). Differences were observed after the 40,000 Units weekly dosing with longer Tmax (38 ± 18 hours) and lower clearance (9.2 ± 4.7 mL/h/kg) during Week 1 when patients were receiving chemotherapy (n = 18) compared with those (22 ± 4.5 hours, 13.9 ± 7.6 mL/h/kg) during Week 3 when patients were not receiving chemotherapy (n = 7).

The bioequivalence between the 10,000 Units/mL citrate-buffered Epoetin alfa formulation and the 40,000 Units/mL phosphate-buffered Epoetin alfa formulation has been demonstrated after SC administration of single 750 Units/kg doses to healthy subjects.

REFERENCES

1. Egrie JC, Strickland TW, Lane J, et al. Characterization and Biological Effects of Recombinant Human Erythropoietin. Immunobiol. 1986;72:213-224.

2. Graber SE, Krantz SB. Erythropoietin and the Control of Red Cell Production. Ann Rev Med. 1978;29:51-66.

3. Eschbach JW, Adamson JW. Anemia of End-Stage Renal Disease (ESRD). Kidney Intl. 1985;28:1-5.

4. Eschbach JW, Egrie JC, Downing MR, et al. Correction of the Anemia of End-Stage Renal Disease with Recombinant Human Erythropoietin. NEJM. 1987;316:73-78.

5. Eschbach JW, Abdulhadi MH, Browne JK, et al. Recombinant Human Erythropoietin in Anemic Patients with End-Stage Renal Disease. Ann Intern Med. 1989;111:992-1000.

6. Eschbach JW, Egrie JC, Downing MR, et al. The Use of Recombinant Human Erythropoietin (r-HuEPO): Effect in End-Stage Renal Disease (ESRD). In: Friedman, Beyer, DeSanto, Giordano, eds. Prevention of Chronic Uremia. Philadelphia, PA: Field and Wood Inc. 1989: 148-155.

7. Egrie JC, Eschbach JW, McGuire T, Adamson JW. Pharmacokinetics of Recombinant Human Erythropoietin (r-HuEPO) Administered to Hemodialysis (HD) Patients. Kidney Intl. 1988;33:262.

8. Paganini E, Garcia J, Ellis P, et al. Clinical Sequelae of Correction of Anemia with Recombinant Human Erythropoietin (r-HuEPO); Urea Kinetics, Dialyzer Function and Reuse. Am J Kid Dis. 1988;11:16.

9. Delano BG, Lundin AP, Golansky R, et al. Dialyzer Urea and Creatinine Clearances Not Significantly Changed in r-HuEPO Treated Maintenance Hemodialysis (MD) Patients. Kidney Intl. 1988;33:219.

10. Stivelman J, Van Wyck D, Ogden D. Use of Recombinant Erythropoietin (r-HuEPO) with High Flux Dialysis (HFD) Does Not Worsen Azotemia or Shorten Access Survival. Kidney Intl. 1988;33:239.

11. Lim VS, DeGowin RL, Zavala D, et al. Recombinant Human Erythropoietin Treatment in Pre-Dialysis Patients: A Double-Blind Placebo Controlled Trial. Ann Int Med. 1989;110:108-114.

12. Stone WJ, Graber SE, Krantz SB, et al. Treatment of the Anemia of Pre-Dialysis Patients with Recombinant Human Erythropoietin: A Randomized, Placebo-Controlled Trial. Am J Med Sci. 1988;296:171-179.

13. Braun A, Ding R, Seidel C, Fies T, Kurtz A, Scharer K. Pharmacokinetics of recombinant human erythropoietin applied subcutaneously to children with chronic renal failure. Pediatr Nephrol. 1993;7:61-64.

14. Geva P, Sherwood JB. Pharmacokinetics of recombinant human erythropoietin (rHuEPO) in pediatric patients on chronic cycling peritoneal dialysis (CCPD). Blood. 1991;78 (Suppl 1):91a.

15. Jabs K, Grant JR, Harmon W, et al. Pharmacokinetics of Epoetin alfa (rHuEPO) in pediatric hemodialysis (HD) patients. J Am Soc Nephrol. 1991;2:380.

16. Kling PJ, Widness JA, Guillery EN, Veng-Pedersen P, Peters C, DeAlarcon PA. Pharmacokinetics and pharmacodynamics of erythropoietin during therapy in an infant with renal failure. J Pediatr. 1992;121:822-825.

39. Widness JA, Veng-Pedersen P, Peters C, Pereira LM, Schmidt RL, Lowe SL. Erythropoietin Pharmacokinetics in Premature Infants: Developmental, Nonlinearity, and Treatment Effects. J Appl Physiol. 1996;80 (1):140-148.

Last reviewed on RxList: 6/20/2012
This monograph has been modified to include the generic and brand name in many instances.

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