Lee T K, Sokoloski T D, Royer G P
Science. 1981 Jul 10;213(4504):233-5. doi: 10.1126/science.6787705.
Biologically active compounds were entrapped in cross-linked serum albumin microbeads. Injection of these drug-impregnated beads into rabbits produced no adverse immunological reactions. Sustained release (20 days) of progesterone was demonstrated in vivo.