Dydroline – SR 20mg Dydrogesterone is a synthetic oral progestogen with high selectivity for progesterone receptors. The sustained release (SR) formulation ensures prolonged action and better compliance. It is used in the management of luteal phase deficiency, menstrual irregularities, threatened or recurrent miscarriage, endometriosis, infertility due to progesterone deficiency, and as part of hormone replacement therapy (HRT).