Steroid and benzyl alcohol diffusion through tissue expanders and double lumen breast implants.

The rate of diffusion of benzyl alcohol (the bacteriostatic agent in the provided diluent) and methylprednisolone 21-hemisuccinate and related rearrangement and hydrolysis products ("steroid") through tissue expanders was examined. The rate of diffusion of steroid through double lumen breast implants was also studied. It was found that benzyl alcohol rapidly diffused through tissue expanders into a saline bath. By 24 hours, one-half of the benzyl alcohol had diffused through the expander. The steroid was much slower to diffuse out of the expander. By 141 days, only 2% of the steroid was found in the bath. This rate was comparable for both the tissue expander and double lumen implants. In addition, a significant amount of the steroid is located in the expander wall, associated with the surface of the expander or precipitated out of solution or both. The clinical significance of these findings is discussed.