The fate of soluble steroids within breast prostheses in humans.

The long-term fate of 6-alpha-methyl-methylprednisolone hemisuccinate (MPHS) placed into breast prostheses prior to implantation in humans was determined. MPHS hydrolyzes to the active form 6-alpha-methylprednisolone (MP) in water, which then diffuses out of the implant. Twenty prostheses were recovered 5.3 to 34.7 months after placement, and the solution inside was analyzed for MPHS and MP. Half-lives were calculated for the hydrolysis of MPHS to MP (3.4 +/- 0.58 months [mean +/- SEM]) and for the diffusion of MP out of the prostheses (20.63 +/- 6.10 months). The large half-lives found imply that MPHS slowly hydrolyzes to MP, and that active steroid is released for a longer time than was previously thought. This long release could be the cause of the long-term effects seen with steroids used in this manner.