Investigation of the Bioaccessibility of Progesterone (Micronized and Nonmicronized), Using an In Vitro Model of the Human Gastrointestinal System
Michelle R.A. de Almeida, August S. Bassani, Samia Hamid, Daniel Banov, Ha Phan

Abstract
The aim of this study is to evaluate the bioaccessibility of two progesterone oral formulations (micronized progesterone 100 mg SR capsules and milled progesterone 100 mg SR capsules), using an in vitro model of the human GI tract. Results show that overall bioaccessibility of micronized progesterone (21.8%) was significantly greater than that of milled progesterone (1.9%), p < 0.001. The higher total bioaccessibility could potentially be due to the smaller particle size of micronized progesterone (< 6 μm), in comparison to that of milled progesterone (approximately 92 μm). One may hypothesize that oral compounded micronized progesterone has the potential for greater bioavailability because of the significantly higher bioaccessibility of micronized progesterone in comparison to milled progesterone. Knowledge of this study’s results may be useful for practitioners when justifying the viability of using micronized progesterone over milled progesterone in the management of postmenopausal symptoms.

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