General remarks - Belma Implants
Belma implants consist of a polymer reservoir surrounded by a hormone diffusion-controlling membrane. They are designed to release daily doses of a hormone to produce physiological or pharmacological plasma concentrations in mice and rats.
Two oestradiol implants have been developed. The first one makes it possible to achieve pre-ovulatory plasma concentrations and is used mainly in hormone-dependent cancer animal models to support tumour cell growth. The second one (E2 Light) makes it possible to deliver pro-oestrous doses and is designed for gynaecological models (e.g., endometriosis).
Table 1 : Plasma concentrations, normal values
| Rat | Mouse | |
| E2 (pg/ml) | 2,4 – 145,4 | 2,4 – 145,4 |
| P4 (ng/ml) | 1,2 – 18,4 | 1,2 – 18,4 |
| T (ng/ml) | 0,66 – 5,4 | 1,7 – 14,4 |
Table 2 : Plasma concentrations, values with Belma implants
| Rat | Mouse | |
| Belma E2 (pg/ml) | 52 - 108 | 41,2 - 105,6 |
| Belma E2L (pg/ml) | 35,2 - 72,0 | |
| Belma P4 (ng/ml) | 5,3 – 11,2 | 3,0 - 5,9 |
| Belma T (ng/ml) | 0,9 - 3,7 | 2,9 - 7,5 |