Kinetics of total octreotide remaining (A), native octreotide content (B) and divalent cation remaining (C) after incubation of PLGA microspheres in PBST at 37°C.
■Formulation 1, no additive was added; ●Formulation 5, 25 mg and 2.5 g CaCl2 was added to O and W2 respectively; ▲Formulation 6, 25 mg and 2.5 g MnCl2 was added to O and W2 respectively; ▼Formulation 7, 5 mg and 2.5 g CaCl2 was added to W1 and W2 respectively; and ✩Formulation 8, 5 mg and 2.5 g MnCl2 was added to W1 and W2 respectively.
W1: internal water phase, O: organic phase; W2: external water phase.