PAIN AFTER SUBCUTANEOUS INJECTION OF ERYT HROPOIETIN - COMPARISON BETWEEN THE NEW FORMULATION OF ALPHA-ERYTHROPOIETIN AND BETA-ERYTHROPOIETIN

We assessed the pain produced by the new formulation of alpha recombin ant human erythropoietin given subcutaneously. We also analysed the po sible influence of the arteriovenous fistula in the arm caused for inj ection. In a double-blind, randomized crossover study we compared the pain produced by subcutaneous injection of the following preparations. Preparation A: new formulation of alpha erythropoietin; preparation B : beta erythropoietin, and preparation C: saline 0,9%. This study was carried out in 21 patients on regular haemodialysis who were previousl y receiving subcutaneously erythropoietin. Two subcutaneous injections of the same preparation were administered, one in each arm, at the en d of three consecutive hemodialysis sessions. The study involved pain assessment by a visual analogue scale and a verbal descriptive scale. A non parametric Friedman test was used with the Bonferroni correction for multiple comparison. The results obtained with both scales were i dentical. The pain was always worse in the arm carrying the fistula, i ndependently of the preparation administered. However, the difference between the two arms was only statistically significant with preparati on A. An interaction between preparation and fistula was observed. As a consequence, the three preparations had to be compared independently in each arm. When the subcutaneous injection was administered in the arm carrying the fistula, the Friedman test showed a statistically sig nificant relationship between pain and preparation; the Bonferroni tes t showed that preparation A produced more pain than preparation B. No statistically significant differences were observed between preparatio ns A and C. nor B and C. On the contrary when the subcutaneous injecti on was administered in the other arm no relation between pain and prep aration was observed. In this arm no differences between the pain prod uced by the new formulation of alpha erythropoietin, beta erythropoiet in or saline 0.9% were seen.