title: Amifostine before fractionated irradiation protects bone growth in rats better than fractionation alone.
abstract: The aim of this study was to determine the independent and combined effects of 100 mg/kg and 200 mg/kg doses of the radioprotectant amifostine and radiotherapy dose fractionation in preserving the integrity of or minimizing damage to the physis during high-dose radiation exposure in an animal model. Thirty-six weanling four-week-old male Sprague-Dawley rats were randomized into six study groups of six animals each. The distal femur and proximal tibia in the right leg of each animal was exposed to X-irradiation, with the contralateral left leg serving as the nonirradiated control. Three groups received a single 25 Gy radiotherapy dose: one group alone, a second group preceded by 100 mg/kg amifostine, and a third preceded by 200 mg/kg amifostine. Three groups received a total of 25 Gy in three equal fractions: one group alone, a second group preceded by 100 mg/kg amifostine, and a third preceded by 200 mg/kg amifostine. Fractionation of the 25 Gy radiation dose reduced the mean percent overall limb growth loss to 44.8%, a statistically significant reduction compared to a mean 58.8% reduced growth with the single 25 Gy dose. Addition of amifostine at 100 and 200 mg/kg before each of the three fractions of radiotherapy further decreased the mean percent overall limb growth loss to 35.2% and 28.5%, respectively, both statistically significant reductions beyond that achieved by fractionation alone.
authors.affiliation: Department of Orthopedic Surgery, SUNY Upstate Medical University at Syracuse, NY 13202, USA. damront@upstate.edu
authors.forename: T A
authors.initials: TA
authors.lastname: Damron
authors.forename: B
authors.initials: B
authors.lastname: Margulies
authors.forename: D
authors.initials: D
authors.lastname: Biskup
authors.forename: J A
authors.initials: JA
authors.lastname: Spadaro
mesh_terms: D004999:Amifostine / Q000494:pharmacology*; D000818:Animals; D001846:Bone Development / Q000187:drug effects* / Q000528:radiation effects*; D019583:Dose Fractionation, Radiation; D004305:Dose-Response Relationship, Drug; D005269:Femur / Q000254:growth & development / Q000528:radiation effects; D008297:Male; D023421:Models, Animal; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000254:growth & development / Q000528:radiation effects
chemical_list: D011837:Radiation-Protective Agents; D004999:Amifostine