These differ in the amount of estrogen given, and whether they are monophasic (the same dose of estrogen and progestogen during each of the 21 days) or multiphasic (varying doses). The introduction of extended-cycle monophasic pills (i.e. Seasonale) has shown that the withdrawal bleeding intervals can be decreased. Monophasic
These are typically given as 21 tablets of estrogen and progestogen, followed by seven 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:

15 μg ethinylestradiol
60 μg gestodene: 24 days + 4 days placebo (Spain: Melodene-15; Israel: Minesse)
20 μg ethinylestradiol
1000 μg norethisterone acetate (UK: Loestrin 20, Galen; US: Loestrin 1/20, Duramed; Microgestin 1/20, Watson Pharmaceuticals; Junel 1/20, Barr)
1000 μg norethisterone acetate: 24 days + 4 days ferrous fumarate only (US: Loestrin 24 Fe, Warner Chilcott)
90 μg levonorgestrel: continuous: 365 days/year, no placebo (US: Amethyst, Watson)
100 μg levonorgestrel: extended cycle: 84 days + 7 days 10 μg ethinylestradiol only (US: LoSeasonique, Teva; CamreseLo, Teva)
100 μg levonorgestrel (US: Alesse, Wyeth; Aviane, Barr; Lessina, Barr; Lutera, Watson; Sronyx, Watson)
150 μg desogestrel (UK: Mercilon, Organon; HU: Novynette, Richter Gedeon)
75 μg gestodene (UK: Femodette, Bayer; RU: Logest, Bayer; Brazil: Femiane, Bayer)
3000 μg drospirenone: 24 days + 4 days placebo (US, EU, RU: Yaz; Bayer Schering Pharma AG.
Butorphanol is a morphinan-type synthetic agonist–antagonist opioid analgesic developed by Bristol-Myers. Butorphanol is most closely structurally related to levorphanol. Butorphanol is available as the tartrate salt in injectable, tablet, and intranasal spray formulations. The tablet form is only used in dogs, cats and horses due to low bioavailability in humans. It was patented in 1971 and approved for medical use in 1979. Medical uses
The most common indication for butorphanol is management of migraine using the intranasal spray formulation. It may also be used parenterally for management of moderate-to-severe pain, as a supplement for balanced general anesthesia, and management of pain during labor. Butorphanol is also quite effective at reducing post-operative shivering (owing to its Kappa agonist activity). Butorphanol is more effective in reducing pain in women than in men. Pharmacology
Butorphanol exhibits partial agonist and antagonist activity at the μ-opioid receptor, as well as partial agonist activity at the κ-opioid receptor (Ki = 2.5 nM; EC50 = 57 nM; Emax = 57%). Stimulation of these receptors on central nervous system neurons causes an intracellular inhibition of adenylate cyclase, closing of influx membrane calcium channels, and opening of membrane potassium channels. This leads to hyperpolarization of the cell membrane potential and suppression of action potential transmission of ascending pain pathways. Because of its κ-agonist activity, at analgesic doses butorphanol increases pulmonary arterial pressure and cardiac work. Additionally, κ-agonism can cause dysphoria at therapeutic or supertherapeutic doses; this gives butorphanol a lower potential for abuse than other opioid drugs.