Optimal route of administration of erythropoietin in chronic renal failure patients: intravenous versus subcutaneous. 
Recombinant human erythropoietin (r-HuEPO) represents the therapy of choice in anaemia of chronic renal failure.  A number of studies have analysed the relative effectiveness of r-HuEPO administered subcutaneously (s.c.)  or intravenously (i.v.)  in haemodialysis patients.  The bioavailability of s.c.  r-HuEPO appears to be low and the absorption of r-HuEPO variable.  Nevertheless, s.c.  administration of r-HuEPO is more efficacious than i.v.  administration, probably due to the better time-averaged plasma concentrations.  Patients on haemodialysis who were on i.v.  r-HuEPO 3 times weekly for 9 months were subsequently successfully maintained on a self-administered s.c.  dosage which was 50% of the i.v.  maintenance dosage and which was later reduced further to 30% of the weekly i.v.  maintenance dosage.  An ongoing European multicentre study has confirmed these findings and demonstrated that s.c.  administration 3 times weekly and once daily was as effective as i.v.  administration 3 times weekly.  Both these s.c.  regimens resulted in a significant dosage reduction (30%) compared with the i.v.  regimen.  The study also found that once weekly s.c.  dosing was as effective as 3 times weekly i.v.  dosing but did not result in a dosage reduction.  Other studies on the optimization of s.c.  r-HuEPO in patients on continuous ambulatory peritoneal dialysis demonstrated that haemoglobin levels following s.c.  r-HuEPO administration (60 U/kg twice weekly) can be further increased by 2 ml iron dextran (containing 50 mg/ml iron) administered i.v.  7-9 weeks after the start of therapy.  Studies on the site of s.c.  injection reveal that injection into the thigh results in more rapid absorption, higher peak concentrations and greater bioavailability than injection into the arm or abdomen.  Data also demonstrate the economic advantage of s.c.  r-HuEPO in high-risk patients.