Historically dosed via injection, suppository, or troche, progesterone is now available in several additional delivery modes.
Of interest is the increase over the last decade in the delivery of hormones through the skin, with various effective modes of application including patches, creams, and gels.
Transdermal delivery of hormones has been found to be effective and well tolerated, with the additional benefit of bypassing the first-pass effect of the liver, allowing for reduced dosages as more of the hormone is directly available for its therapeutic effect rather than being mostly metabolized (see Hermannin our reference article here).
Micronization of progesterone in oral formulations has also benefited absorption, and some doctors prefer to prescribe oral micronized progesterone because of its tendency to induce drowsiness and thus aid sleep, which may help women who are troubled with night-time menopausal symptoms.
With thanks to http://www.womeninbalance.org