Studies of the slow releasing of testosterone from radiation-polymerized testicular prostheses implanted subcutaneously in the back of castrated rabbits

A controlled release testicular prosthesis containing testosterone, which was previously dissolved in 2-hydroxyethyl methacrylate (HEMA) at a temperature of 80°C, was prepared by radiation-induced polymerization in the supercooled state at a low temperature. The daily dose of testosterone released i...

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Bibliographic Details
Published in:Biomaterials 1987-03, Vol.8 (2), p.124-128
Main Authors: Yoshida, Masaru, Asano, Masaharu, Kaetsu, Isao, Imai, Kyoichi, Mashimo, Tooru, Yuasa, Hisako, Yamanaka, Hidetoshi, Kawaharada, Umeko, Suzuki, Keiji
Format: Article
Language:English
Subjects:
Animals
Biocompatible Materials
castrated rabbit prosthesis
Drug delivery
Male
Orchiectomy
poly(HEMA)
Polyhydroxyethyl Methacrylate - radiation effects
Prostheses and Implants
Rabbits
radiation-polymerized polymer
Testis
testosterone
Testosterone - administration & dosage
Testosterone - blood
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Summary:A controlled release testicular prosthesis containing testosterone, which was previously dissolved in 2-hydroxyethyl methacrylate (HEMA) at a temperature of 80°C, was prepared by radiation-induced polymerization in the supercooled state at a low temperature. The daily dose of testosterone released in vitro from the poly(HEMA) testicular prosthesis was kept constant at a rate of 5.5 ± 1.5 mg/d throughout an experimental period of 900 d. In the in vivo experiments, the poly (HEMA) testicular prosthesis was implanted subcutaneously in the back of castrated rabbits over a maximum period of 11 mnth. The cumulative amounts of testosterone released in vitro and in vivo from the poly (HEMA) testicular prosthesis for a period of 11 mnth were found to be 2.1 g (30.0 wt% of initial drug) and 0.9 g (12.8 wt% of initial drug), respectively. The serum testosterone level in castrated rabbits with a poly(HEMA) testicular prosthesis rapidly decreased for periods up to 2 mnth (after increasing during the first 2 wk), then showed a moderate decrease for a few months, and finally held constant at a level of 10 ng/ml throughout the experimental period. It was concluded that a slight amount of testosterone is continuously released in vivo from the radiation-polymerized poly(HEMA) testicular prosthesis over a long period analogous with that in vitro.
ISSN:0142-9612
1878-5905
DOI:10.1016/0142-9612(87)90101-3