As of 2021, more than 95% of prescriptions are for combined hormonal birth control forms containing the synthetic estrogen ethinylestradiol (EE).[7] Hence, estradiol-based birth control pills are still not widely used.[7]
Birth control pills containing estradiol have less impact on liver protein synthesis than ethinylestradiol-containing birth control pills, and it is thought that for this reason, they may pose less of a risk of venous thromboembolism (VTE).[8][9] In accordance, although birth control pills containing estradiol valerate/dienogest are associated with a significantly increased risk of VTE, they are associated with a significantly lower risk of venous thromboembolism than birth control pills containing ethinylestradiol and a progestin.[10] The risk of VTE with estradiol/nomegestrol acetate birth control pills is under study.[11]
Incidence of irregular vaginal bleeding may be higher with estradiol-containing birth control pills in relation to the fact that estradiol is a weaker estrogen than ethinylestradiol in the endometrium.[3]
^"WJPPS | ABSTRACT"(PDF). World Journal of Pharmacy and Pharmaceutical Sciences.
^ abMawet, M; Gaspard, Ulysse; Foidart, JM (2021). "Estetrol as estrogen in a combined oral contraceptive, from the first in-human study to the contraceptive efficacy"(PDF). European Gynecology and Obstetrics. 3 (1): 13–21. On the other side, only three different estrogens have been used in COC since 1961: the first one was the pro-drug mestranol rapidly replaced by its potent active form, ethinylestradiol (EE). Ethinylestradiol has remained the only estrogen used in COC during more than four decades. After initial unsuccessful attempts, estradiol (E2) was finally introduced into two COCs in the early 2010': in the form of the pro-drug E2 valerate in combination with dienogest (E2V/DNG) and in the form of E2 in combination with nomegestrol acetate [4, 5]. However, these E2-containing COCs are less prescribed as over 95% of combined hormonal contraceptive users still utilize an EE-containing product.
^Douxfils J, Morimont L, Bouvy C (October 2020). "Oral Contraceptives and Venous Thromboembolism: Focus on Testing that May Enable Prediction and Assessment of the Risk". Semin Thromb Hemost. 46 (8): 872–886. doi:10.1055/s-0040-1714140. PMID33080636. S2CID224821517.
^Kuhnz W, Gansau C, Mahler M (September 1993). "Pharmacokinetics of estradiol, free and total estrone, in young women following single intravenous and oral administration of 17β-estradiol". Arzneimittelforschung. 43 (9): 966–73. ISSN0004-4172. PMID8240460.
^"A randomized, double-blind study of two combined oral contraceptives containing the same progestogen, but different estrogens. World Health Organization Task Force on Oral Contraception". Contraception. 21 (5): 445–59. May 1980. doi:10.1016/0010-7824(80)90010-4. PMID7428356.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction