Design and evaluation of a biodegradable implant for improved delivery of oestradiol-17β to steers

• Published in: International journal of pharmaceutics Vol. 89; no. 3; pp. 251 - 259
• Main Authors: Deasy, P.B., Finan, M.P., Klatt, P.R., Hornykiewytsch, T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.02.1993; Elsevier
• Subjects: Biodegradable implant; Biological and medical sciences; Estradiol-17; General pharmacology; Growth promotion; Improved delivery; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polylactic acid copolymer; Steer; Growth promotion; Improved delivery; Polylactic acid copolymer; Estradiol-17; Steer; Biodegradable implant; Pharmaceutical technology; Bovine; Implant; Lactic acid copolymer; Estrogen; 17β-Estradiol; In vitro; Ovarian hormone; Design; In vivo; Vertebrata; Mammalia; Animal; Glycolic acid; Dosage form; Active ingredient; Artiodactyla; Sex steroid hormone; Pharmacokinetics; Ungulata; Release
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/0378-5173(93)90251-A

Novel biodegradable implants were designed for extended delivery of effective levels of the growth promoting agent, oestradiol-17β, to steers. They were usually composed of five alternating active containing tablets measuring 4 mm diameter × 2 mm thick aligned face on with four inactive spacer tablets of similar dimensions. Both compact types were composed of various copolymers of polylactic-glycolic acid, chosen with a higher glycolide content in the spacer units to promote faster degradation. The resultant controlled increase in surface area of exposed active containing compacts in the composite implant gave increasing release with time, whose rate could be varied by copolymer ratio in the active compacts, their drug loading and by the composition and thickness of spacer compacts. The initial burst of release from poorly entrapped drug on the surface of an implant was minimized by reducing the drug loading in the terminal active compacts, which tend to contribute disproportionately to the initial surface area of the device. Prolonged dissolution testing on single compacts and composite implants facilitated selection of implant designs which showed the desired increase in active release from about 0.25 mg to 0.5 mg daily over 3–6 months implantation in limited numbers of steers with associated favourable weight gain, compared to untreated controls. The novel implants described have potential for the improved delivery of other classes of drugs.