Quingestrone, also known as progesterone 3-cyclopentyl enol ether (PCPE) and sold under the brand name Enol-Luteovis, is a progestin medication which was previously used in birth control pills in Italy but is now no longer marketed.

[2][3] The medication was studied in the clinical prevention of miscarriage during pregnancy, but insufficient efficacy was observed at the dosage assessed (100 mg/day orally).

[18][12] Similarly to progesterone, dydrogesterone, and hydroxyprogesterone caproate, quingestrone is a pure progestogen and lacks any androgenic effects.

[8][11] When administered orally or intraperitoneally in animals, the medication showed 1/80 and 1/20 the potency of subcutaneously injected progesterone, respectively.

[8] The fact that quingestrone is more potent by intraperitoneal than oral administration in animals suggests that it is transformed into a less active metabolite in the intestines.

[26][27] Relative to progesterone, quingestrone shows improved pharmacokinetics, including higher potency,[25] oral activity,[28] and a longer terminal half-life and hence duration of action.

[24] The C3 enol ethers of progesterone are less suited for use via depot injection relative to progestogen esters like hydroxyprogesterone caproate due to their susceptibility to oxidative metabolism.

[6][12] Quingestrone is the generic name of the drug and its INNTooltip International Nonproprietary Name and USANTooltip United States Adopted Name.