Sustained Efficacy of Erythropoietin with a Hydroxyapatite Carrier Administered in Mice

Abstract

ABSTRACT. For chronic kidney disease patients with renal anemia, recombinant human erythropoietin (rHuEPO) is a very effective drug; however, the treatment regime is troublesome, requiring multiple administrations each week. In the present study, we examined the efficiency of hydroxyapatite (HAp) as a drug delivery carrier for the sustained release of erythropoietin (EPO) to reduce the frequency of administration. Spray-dried HAp microparticles, formed from zinc-containing HAp (Zn-HAp) and Zn-HAp calcined at 400C, were used as carriers of EPO, and five Zn-HAp formulation samples incorporating EPO were prepared; no formulation, poly-L-lactic acid (PLA) formulation, zinc (Zn) formulation, Zn/PLA formulation, and calcined/Zn/PLA formulation. ICR mice were administered these samples or commercial rHuEPO (Epogin) as a control from dorsal neck subcutaneous, and hematological and histopathological analyses, including enzyme-linked immunosorbent assay for plasma EPO concentration, were performed. An increase in the blood EPO level was detected on days 3 and 8 post-administration. Peak hematopoiesis was delayed and higher hematological values were obtained on day 14 post-administration with no serious adverse reactions compared with the control. The Zn/PLA formulation sample was found to be most effective in reducing the initial peak while sustaining the delayed release of EPO. In conclusion, the Zn-HAp formulation samples were considered to be useful carriers for the sustained release of EPO, and the Zn/PLA formulation appears to be the most effective of five Zn-HAp formulation samples in sustaining EPO release.KEY WORDS: anemia, erythropoietin, hydroxyapatite, sustained release.

Amelioration of Anemia in the ICGN Mouse, a Renal Anemia Model, with a Subcutaneous Bolus Injection of Erythropoietin Adsorbed to Hydroxyapatite Matrix

“…Previously, we examined the efficiency of hematopoiesis with five Zn-HAp formulations adsorbed rhEPO (no formulation, PLA formulation, Zn formulation, Zn/PLA formulation, and calcination/Zn/PLA formulation) in vivo. When 500 U of rhEPO-HAp was injected subcutaneously in the dorsal neck, Zn and Zn/PLA formulations only showed sustained efficiency in the hematopoiesis and plasma rhEPO levels [25]. Therefore, these 2 formulations were examined their efficiency for the improvement of anemia using ICGN mice, renal anemia model.…”

“…Two types of zinc-containing HAp (Zn-HAp) formulation adsorbed rhEPO, Zn and Zn/PLA formulations, were prepared using the process described previously [25].…”

“…Hemanalysis, weight change of organs, and histpathological analysis post-administration: The two types of formulations suspended in saline or aqueous rhEPO (Epogin, Chugai Pharmaceutical, Tokyo, Japan) as a control were administered subcutaneously in the dorsal neck at the dose of 500 U/body to anemic mice, according to our previous report [25]. At least 50 U of rhEPO was able to absorb to 1 mg of HAp.…”

“…At least 50 U of rhEPO was able to absorb to 1 mg of HAp. In previous studies, when 500 U of rhEPOHAp injected subcutaneously, these mice showed the sustained efficacy of hemopoiesis without any side effects [25]. Thus, we used this dosage (500 U/body) to compare between both rhEPO-HAp and aqueous rhEPO in the present study.…”

“…Previously, we examined the efficiency of hematopoiesis using five hydroxyapatite (HAp) formulations for the sus-tained release of rhEPO in vivo [25]. As a result, in mice administered zinc (Zn) formulation and Zn and poly-L-lactic acid (PLA) formulation, plasma rhEPO was detected for a long time, peak hematopoiesis was prolonged, and higher hematological values were achieved.…”