Oral contraceptive formulations detailed information
Oral contraceptives come in a variety of formulations. The main division is between combined oral contraceptive pills, containing both estrogen and synthetic progestogens (strictly progestins, the term used in the United States, but the former term is used in the United Kingdom), and progestogen only pills (mini-pills). Combined oral contraceptive pills also come in varying types, including varying doses of estrogen, and whether the dose of estrogen or progestogen changes from week to week.

# How they work
Combination pills usually work by preventing a woman's ovaries from releasing eggs (ovulation). They also thicken the cervical mucus, which keeps sperm from joining with an egg. The hormones in combination and progestogen-only pills also thin the lining of the uterus. In theory, this could prevent pregnancy by interfering with implantation of a blastocyst.

# Combined oral contraceptive pills
All contain an estrogen, ethinyl estradiol or mestranol (the inactive 3-methyl ether of ethinyl estradiol, which must be metabolized by the liver into the active ethinyl estradiol; 50 g of mestranol is equivalent to only 35 g of ethinyl estradiol and should not be used when high-dose (50 g ethinyl estradiol) estrogen pills are needed; mestranol was the estrogen used in the first oral contraceptive, Enovid), although in varying amounts, and one of a number of different progestogens. They are usually taken for 21 days with then a 7 day gap during which a withdrawal bleed (often, but incorrectly, referred to as a menstrual period) occurs. These differ in the amount of estrogen given, and whether they are monophasic (only one dose of estrogen and progestogen during the 21 days) or multiphasic (varying doses). The introduction of extended-cycle monophasic pills (i.e. Seasonale) has shown that the menstrual intervals can be decreased.

## Monophasic
These are typically given as 21 tablets of estrogen and progestogen, followed by 7 tablets of placebo or an iron supplement, although some newer formulations contain more active tablets and fewer placebos. Everyday regimens (Microgynon 30 ED, Femodene ED, Logynon ED), which include seven inactive placebo pills, are rarely used in UK practice. Different formulations contain different amounts of estrogen and progestogen:
- 20 g ethinyl estradiol
1000 g norethindrone acetate (UK: Loestrin 20, Galen; US: Loestrin 1/20, Duramed; Microgestin 1/20, Watson; Junel 1/20, Barr)
1000 g norethindrone acetate  24 days + 4 days ferrous fumarate only (US: Loestrin 24 Fe, Warner Chilcott)
90 g levonorgestrel  continuous: 365 days/year, no placebo (US: Lybrel, Wyeth)
100 g levonorgestrel (US: Alesse, Wyeth; Aviane, Barr; Lessina, Barr; Lutera, Watson; Sronyx, Watson)
150 g desogestrel (UK: Mercilon, Organon)
150 g desogestrel  21 days + 2 days placebo + 5 days 10 g ethinyl estradiol only (US: Mircette, Duramed; Kariva, Barr)
75 g gestodene (UK: Femodette, Bayer)
3000 g drospirenone  24 days + 4 days placebo (US: Yaz, Bayer)
- 1000 g norethindrone acetate (UK: Loestrin 20, Galen; US: Loestrin 1/20, Duramed; Microgestin 1/20, Watson; Junel 1/20, Barr)
- 1000 g norethindrone acetate  24 days + 4 days ferrous fumarate only (US: Loestrin 24 Fe, Warner Chilcott)
- 90 g levonorgestrel  continuous: 365 days/year, no placebo (US: Lybrel, Wyeth)
- 100 g levonorgestrel (US: Alesse, Wyeth; Aviane, Barr; Lessina, Barr; Lutera, Watson; Sronyx, Watson)
- 150 g desogestrel (UK: Mercilon, Organon)
- 150 g desogestrel  21 days + 2 days placebo + 5 days 10 g ethinyl estradiol only (US: Mircette, Duramed; Kariva, Barr)
- 75 g gestodene (UK: Femodette, Bayer)
- 3000 g drospirenone  24 days + 4 days placebo (US: Yaz, Bayer)
- 30 g ethinyl estradiol
1500 g norethindrone acetate (UK: Loestrin 30, Galen; US: Loestrin 1.5/30, Duramed; Microgestin 1.5/30, Watson; Junel 1.5/30, Barr)
300 g norgestrel (US: Lo/Ovral, Wyeth; Low-Orgestrel, Watson; Cryselle, Barr)
150 g levonorgestrel (UK: Ovranette, Wyeth; Microgynon 30, Microgynon 30 ED, Bayer; US: Nordette, Duramed; Levora, Watson; Portia, Barr)
150 g levonorgestrel  extended cycle: 84 days + 7 days placebo (US: Seasonale, Duramed; Quasense, Watson; Jolesa, Barr)
150 g levonorgestrel  extended cycle: 84 days + 7 days 10 g ethinyl estradiol only (US: Seasonique, Duramed)
150 g desogestrel (UK: Marvelon, Organon; US: Desogen, Organon; Ortho-Cept, Ortho-McNeil; Apri, Barr)
75 g gestodene (UK: Femodene, Femodene ED, Bayer; Minulet, Wyeth)
3000 g drospirenone (US: Yasmin, Bayer)
- 1500 g norethindrone acetate (UK: Loestrin 30, Galen; US: Loestrin 1.5/30, Duramed; Microgestin 1.5/30, Watson; Junel 1.5/30, Barr)
- 300 g norgestrel (US: Lo/Ovral, Wyeth; Low-Orgestrel, Watson; Cryselle, Barr)
- 150 g levonorgestrel (UK: Ovranette, Wyeth; Microgynon 30, Microgynon 30 ED, Bayer; US: Nordette, Duramed; Levora, Watson; Portia, Barr)
- 150 g levonorgestrel  extended cycle: 84 days + 7 days placebo (US: Seasonale, Duramed; Quasense, Watson; Jolesa, Barr)
- 150 g levonorgestrel  extended cycle: 84 days + 7 days 10 g ethinyl estradiol only (US: Seasonique, Duramed)
- 150 g desogestrel (UK: Marvelon, Organon; US: Desogen, Organon; Ortho-Cept, Ortho-McNeil; Apri, Barr)
- 75 g gestodene (UK: Femodene, Femodene ED, Bayer; Minulet, Wyeth)
- 3000 g drospirenone (US: Yasmin, Bayer)
- 35 g ethinyl estradiol
400 g norethindrone  chewable, spearmint flavor (US: Femcon Fe, Warner Chilcott)
400 g norethindrone (US: Ovcon 35, Warner Chilcott; Balziva, Barr)
500 g norethindrone (UK: Ovysmen, Janssen-Cilag; Brevinor, Pfizer; US: Modicon, Ortho-McNeil; Brevicon, Watson; Nortrel 0.5/35, Barr)
1000 g norethindrone (UK: Norimin, Pfizer; US: Ortho-Novum 1/35, Ortho-McNeil; Norinyl 1/35, Watson; Necon, Watson; Nortrel 1/35, Barr)
1000 g ethynodiol diacetate (US: Demulen 1/35, Pfizer; Zovia 1/35, Watson; Kelnor, Barr)
250 g norgestimate (UK: Cilest, Janssen-Cilag; US: Ortho Cyclen, Ortho-McNeil; MonoNessa, Watson; Sprintec, Barr)
2000 g cyproterone acetate  only for severe acne or severe hirsutism (UK: Dianette, Bayer)
- 400 g norethindrone  chewable, spearmint flavor (US: Femcon Fe, Warner Chilcott)
- 400 g norethindrone (US: Ovcon 35, Warner Chilcott; Balziva, Barr)
- 500 g norethindrone (UK: Ovysmen, Janssen-Cilag; Brevinor, Pfizer; US: Modicon, Ortho-McNeil; Brevicon, Watson; Nortrel 0.5/35, Barr)
- 1000 g norethindrone (UK: Norimin, Pfizer; US: Ortho-Novum 1/35, Ortho-McNeil; Norinyl 1/35, Watson; Necon, Watson; Nortrel 1/35, Barr)
- 1000 g ethynodiol diacetate (US: Demulen 1/35, Pfizer; Zovia 1/35, Watson; Kelnor, Barr)
- 250 g norgestimate (UK: Cilest, Janssen-Cilag; US: Ortho Cyclen, Ortho-McNeil; MonoNessa, Watson; Sprintec, Barr)
- 2000 g cyproterone acetate  only for severe acne or severe hirsutism (UK: Dianette, Bayer)
- 50 g mestranol (equivalent to 35 g ethinyl estradiol)
1000 g norethindrone (UK: Norinyl-1, Pfizer; US: Ortho-Novum 1/50; Ortho-McNeil; Norinyl 1/50, Watson; Necon 1/50, Watson)
- 1000 g norethindrone (UK: Norinyl-1, Pfizer; US: Ortho-Novum 1/50; Ortho-McNeil; Norinyl 1/50, Watson; Necon 1/50, Watson)
- 50 g ethinyl estradiol
1000 g norethindrone (US: Ovcon 50, Warner Chilcott)
1000 g ethynodiol diacetate (US: Demulen 1/50, Pfizer; Zovia 1/50, Watson)
500 g norgestrel (US: Ogestrel, Watson)
- 1000 g norethindrone (US: Ovcon 50, Warner Chilcott)
- 1000 g ethynodiol diacetate (US: Demulen 1/50, Pfizer; Zovia 1/50, Watson)
- 500 g norgestrel (US: Ogestrel, Watson)

## Multiphasic
- 25 g ethinyl estradiol  triphasic
ethinyl estradiol/norgestimate combination with 7 tablets 25 g/180 g, 7 tablets 25 g/215 g, 7 tablets 25 g/250 g followed by 7 placebos (Ortho Tri-Cyclen Lo, Ortho-McNeil)
ethinyl estradiol/desogestrel combination with 7 tablets 25 g/100 g, 7 tablets 25 g/125 g, 7 tablets 25 g/150 g, followed by 7 tablets of ferric oxide (US: Cyclessa, Organon; Velivet, Barr)
- ethinyl estradiol/norgestimate combination with 7 tablets 25 g/180 g, 7 tablets 25 g/215 g, 7 tablets 25 g/250 g followed by 7 placebos (Ortho Tri-Cyclen Lo, Ortho-McNeil)
- ethinyl estradiol/desogestrel combination with 7 tablets 25 g/100 g, 7 tablets 25 g/125 g, 7 tablets 25 g/150 g, followed by 7 tablets of ferric oxide (US: Cyclessa, Organon; Velivet, Barr)
- 20/30/35 g ethinyl estradiol  estrophasic
ethinyl estradiol/norethindrone acetate combination with 5 tablets 20 g/1000 g, 7 tablets 30 g/1000 g, 9 tablets 35 g/1000 g, followed by 7 tablets of ferrous fumarate 75 mg (US: Estrostep Fe, Warner Chilcott)
- ethinyl estradiol/norethindrone acetate combination with 5 tablets 20 g/1000 g, 7 tablets 30 g/1000 g, 9 tablets 35 g/1000 g, followed by 7 tablets of ferrous fumarate 75 mg (US: Estrostep Fe, Warner Chilcott)
- 30/40/30 g ethinyl estradiol  triphasic
ethinyl estradiol/levonorgestrel combination with 6 tablets 30 g/50 g, 5 tablets 40 g/75 g, 10 tablets 30 g/125 g (UK: Trinordiol, Wyeth; Logynon, Logynon ED, Bayer; US: Triphasil, Wyeth; Trivora, Watson; Enpresse, Barr)
ethinyl estradiol/gestodene combination with 6 tablets 30 g/50 g, 5 tablets 40 g/70 g, 10 tablets 30 g/100 g (UK: Triadene, Bayer; Tri-Minulet, Wyeth)
- ethinyl estradiol/levonorgestrel combination with 6 tablets 30 g/50 g, 5 tablets 40 g/75 g, 10 tablets 30 g/125 g (UK: Trinordiol, Wyeth; Logynon, Logynon ED, Bayer; US: Triphasil, Wyeth; Trivora, Watson; Enpresse, Barr)
- ethinyl estradiol/gestodene combination with 6 tablets 30 g/50 g, 5 tablets 40 g/70 g, 10 tablets 30 g/100 g (UK: Triadene, Bayer; Tri-Minulet, Wyeth)
- 35 g ethinyl estradiol  triphasic
ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 9 tablets 35 g/1000 g, 5 tablets 35 g/500 g (UK: Synphase, Pfizer; US: Tri-Norinyl, Watson; Leena, Watson)
ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 7 tablets 35 g/750 g, 7 tablets 35 g/1000 g (UK: TriNovum, Janssen-Cilag; US: Ortho-Novum 7/7/7, Ortho-McNeil; Necon 7/7/7, Watson; Nortrel 7/7/7, Barr)
ethinyl estradiol/norgestimate combination with 7 tablets 35 g/180 g, 7 tablets 35 g/215 g,  7 tablets 35 g/250 g followed by 7 placebos (Ortho Tri-Cyclen, Ortho-McNeil; TriNessa, Watson; Tri-Sprintec, Barr)
- ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 9 tablets 35 g/1000 g, 5 tablets 35 g/500 g (UK: Synphase, Pfizer; US: Tri-Norinyl, Watson; Leena, Watson)
- ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 7 tablets 35 g/750 g, 7 tablets 35 g/1000 g (UK: TriNovum, Janssen-Cilag; US: Ortho-Novum 7/7/7, Ortho-McNeil; Necon 7/7/7, Watson; Nortrel 7/7/7, Barr)
- ethinyl estradiol/norgestimate combination with 7 tablets 35 g/180 g, 7 tablets 35 g/215 g,  7 tablets 35 g/250 g followed by 7 placebos (Ortho Tri-Cyclen, Ortho-McNeil; TriNessa, Watson; Tri-Sprintec, Barr)
- 35 g ethinyl estradiol  biphasic
ethinyl estradiol/norethindrone combination with 10 tablets 35 g/500 g, 11 tablets 35 g/1000 g, followed by 7 placebos (US: Ortho-Novum 10/11, Ortho-McNeil; Necon 10/11, Watson)
ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 14 tablets 35 g/1000 g (UK: BiNovum, Janssen-Cilag)
- ethinyl estradiol/norethindrone combination with 10 tablets 35 g/500 g, 11 tablets 35 g/1000 g, followed by 7 placebos (US: Ortho-Novum 10/11, Ortho-McNeil; Necon 10/11, Watson)
- ethinyl estradiol/norethindrone combination with 7 tablets 35 g/500 g, 14 tablets 35 g/1000 g (UK: BiNovum, Janssen-Cilag)

# Progestogen only pills
Progestogen only pills (POPs) use progestogen alone with doses taken continuously and no gap between packs taken. Women may experience irregular light bleeds on POPs, and whilst irregular in the first few months of taking, usually settles to a regular pattern in time.
The following progestogens are used:
- 350 g norethindrone (UK: Micronor, Janssen-Cilag; Noriday, Pfizer; US: Micronor, Ortho-McNeil; Nor-QD, Watson; Nora-BE, Watson; Jolivette, Watson; Camila, Barr; Errin, Barr)
- 500 g ethynodiol diacetate (UK: Femulen, Pfizer)
- 30 g levonorgestrel (UK: Norgeston, Bayer)
- 75 g desogestrel (UK: Cerazette, Organon)