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Oral Contraceptives

Oral Contraceptives. Estrogen and Progestin. Hormones . = “chemical messenger from one cell to another” 4 classes of Hormones Amine Derived Hormones Peptide Hormones Steroid Hormones Lipid and Phospholipid Hormones Steroid Hormones - derived from cholesterol

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Oral Contraceptives

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  1. Oral Contraceptives Estrogen and Progestin

  2. Hormones = “chemical messenger from one cell to another” 4 classes of Hormones • Amine Derived Hormones • Peptide Hormones • Steroid Hormones • Lipid and Phospholipid Hormones Steroid Hormones -derived from cholesterol -primarily produced in adrenal cortex or gonads Types of Steroid Hormones • Anabolic steroids • Corticosteroids • Sex hormones Major steps in Steroid Hormone Binding • http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter47/animations.html# cholesterol

  3. The Sex Steroids • Female Sex Steroids Include: Estrogens and Progestins The most potent estrogen is estradiol. • Male Sex Steroids Include: Androgens The androgen found in blood is testosterone.

  4. Female or Male? • All three classes of endogenous steroids are present in both males and females. • But, the production and circulating plasma levels of estrogens and progestins are higher in females and that of androgens are higher in males.

  5. Female Sex Drive • However, sexual desire in women is probably more dependent upon androgens, secreted by the adrenal glands and ovaries, than estrogen. • Sex drive is maintained beyond menopause, a time when estrogen levels become very low.

  6. Interaction of Hormones with Surface Proteins

  7. Ovulation • Follicular phase • LH and FSH concentrations increase due to GnRH • Follicular growth • Antrum fluid volume increases • Blister forms in ovary • Ovulation Phase • Follicle released from ovary  secretes estrogen • Corpus lueteum triggers release of progesterones and estrogens

  8. Ovulation

  9. During Pregnancy • The levels of estrogen and progesterone increase during pregnancy • A good source of estrogens is the urine of pregnant women.

  10. History of Oral Contraceptives • 1937- discovery of effects of progesterone on ovulation • 1940’s- Russell Marker isolates progesterone from Mexican yams • 1951- Luis Miramontes synthesizes 1st progestin • 1950’s: Studies show that the combination of an estrogen and a progestin prevents contraception. • 1960- FDA approves “the pill” • 1963- 1st oral contraceptive put on drug market • 1965- number one form of birth control • Late 1970’s- FDA mandated warning that indicated oral contraceptives carried risks of cancer and blood clots

  11. Uses of Oral Contraceptives • Primary Use • Prevent pregnancy • Secondary Uses • Heavy or irregular menstruation • Endometriosis • polycystic ovary syndrome • dysfunctional uterine bleeding

  12. What’s in “The Pill” • 20-40 micrograms ethinyl estradiol (synthetic form of estrogen) • Varying amounts of either levonorgestrel or norethindrone as the progestagen component • Types of Regimens • 21-day or 28-day pack

  13. Combined mode of action of estrogen and progestin • Prevents ovulation • Thickens mucous in cervix • Thins endometrium

  14. How does it work? • Estrogen and progesterone can inhibit pituitary gonadotropin release, thereby preventing ovulation. • In practice, oral contraceptives, particularly the minipill (contains only progesterone-like substances), do not always prevent ovulation, but they are still effective because they have other contraceptive effects.

  15. How does it work? • Progestogens affect the composition of the cervical mucus, reducing the ability of the sperm to pass through the cervix. • They also inhibit the estrogen-induced proliferation of the endometrium, making it inhospitable for implantation.

  16. Gonadotropin Releasing Hormone (GnRH) • Synthesized by hypothalamus • Stimulates anterior pituitary gland to release FSH and LH • A decapetide (contains 10 amino acids) pGlu-His-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 • secretion begins at puberty • Primary Effects • secretion of estrogen and progesterone in females • secretion of testosterone in males

  17. Estrogen • Primary female sex hormone • Roles of estrogen: • To develop secondary female sex characteristics • Thicken the endometrium • Regulate menstrual cycle • Regulation • Production of estrogen regulated by Follicle Stimulating hormone (FSH) and Luetinizing hormone (LH), both produced in the anterior lobe of the pituitary gland • Hypothalamus→GnRH→ Pituitary→FSH→Follicle→Estrogens

  18. Naturally occurring estrogens Estradiol Estriol Estrone

  19. Metabolism of Estradiol • Estradiol itself is not orally bioavailable, due to its rapid oxidation in the liver

  20. Biosynthesis of estradiol

  21. Synthetic Estrogens

  22. Synthetic Estrogens • Note that the synthetic estrogens contain a tertiary alcohol, instead of a secondary alcohol. • This tertiary acetylenic alcohol cannot be oxidized to the corresponding ketone, thus is metabolically stable, and orally bioavailable.

  23. Estrogen Receptors Two types of Receptors • ER alpha • ER beta Mode of Action- 1) Estrogen passes through phospholipid bilayer 2) Ligand binds in hydrophobic region of receptor forming cap over ligand binding pocket 3) Estrogen and ER complex bind to estrogen response element in the nucleus to initiate transcription 4) Translation creates proteins which target various organs and processes in the female body

  24. Progesterone • Produced by • Adrenal glands • Gonads • Brain • Placenta (only during pregnancy) • Regulation- stimulated by the production of LH • Hypothalamus→GnRH→ Pituitary→LH→Corpus luteum→Progesterone • Primary Effect-prepares uterus for implantation by the proliferation of endometrium; prepares body for pregnancy • Natural progesterone- destroys digestive system when consumed orally ALL oral contraceptives contain progestin, synthetic form of progesterone

  25. Conversion of pregnenolone to progesterone pregnenolone progesterone

  26. Metabolism of Progesterone • Progesterone itself is not orally bioavailable, partially due to its metabolism

  27. Progestins • Types 1) C19- derived from testosterone 2) C21- derived from progesterone • Role • in adequate doses it inhibits ovulation • Makes your body think that it is pregnant • Reduces levels of FSH and LH • Binding • Interacts with progesterone receptors either by entering cells through phospholipid bilayer or by interacting with surface proteins

  28. Structure of Progestins

  29. Brands of Oral Contraceptives • Loestrin • Lo/Ovral • Mircette • ModiCo • Necon • N.E.E. • Nelova • Nordette • Norethin • Norinyl • Ortho-Cept • Ortho-Cyclen • Ortho-Novum • Ortho Tri-Cyclen • Ovcon • Ovral • Tri-Levlen • Tri-Noriny • Triphasil • Trivora • Zovia • Alesse • Brevicon • Cyclessa • Demulen • Desogen • Estrostep • Genora • Intercon • Jenest • Levlen • Levlite • Levora

  30. Side Effects of Oral Contraceptives • Changes in: • Weight • Sexual desire • Vaginal discharge • Menstrual flow • Breast size • Blood pressure • complexion • Other Common side effects: • Breakthrough bleeding • Nausea headaches • Urinary tract infection • Depression • Gum inflammation

  31. Abortifacients • An antagonist of progesterone can interfere with the early stages of pregnancy

  32. Future of Oral Contraceptives • Researchers continually trying to minimize adverse side effects of oral contraceptives • Pharmaceutical companies have to compete with latest forms of contraception • Contraceptive vaccines • Vaginal rings • Intrauterine Contraception • Cervical caps • Transdermal patch • Implants and injectables

  33. References • http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601050.html • http://en.wikipedia.org/wiki/Estrogen • http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/SexHormones.html • http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookREPROD.html • http://en.wikipedia.org/wiki/Gonadotropin_releasing_hormone • http://www.contraceptiononline.org/slides/slide01.cfm?q=progestin+chemical+structures&dpg=1 • http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hormones.html • http://www.contraceptiononline.org/contrareport/article01.cfm?art=93 • http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/G_Proteins.html

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