Most progestins used in COCs are related to testosterone and may impart androgenic side afects such as acne and adverse HDL and LDL levels. To avoid these efects, antiandrogenic progestins have been introduced and include dienogest and nomegestroL acetate. he latter is used in a COC approved outside the United States. Despite these pharmacological differences, the true advantage of one progestin over another is less apparent clinically (Lawrie, 2011; Moreau, 2007).
Another progestin, drospirenone, is structurally similar to spironolactone. he doses in currently marketed COCs have efects similar to 25 mg of this diuretic (Seeger, 2007). Drospirenone displays antiandrogenic activity, provides an antialdosterone action to minimize water retention, and has antimineralocorticoid properties that may, in theory, cause potassium retention and hyperkalemia (Krattenmacher, 2000). hus, it is avoided in women with renal or adrenal insuiciency or with hepatic dysfunction. Moreover, serum potassium level monitoring is recommended in the first month for patients chronically treated concomitantly with any drug associated with potassium retention. hese include NSAIDs, angiotensinconverting enzyme (ACE) inhibitors, angiotensin II antagonists, heparin, aldosterone antagonists, and potassium-sparing diuretics (Bayer HealthCare Pharmaceuticals, 2015).
Since the development of COCs, their estrogen and progestin content has dropped remarkably to minimize adverse efects. Currently, the lowest acceptable dose is limited by the ability to prevent pregnancy and to avoid unacceptable breakthrough bleeding. hus, the daily estrogen content varies from 10 to 50 1g of ethinyl estradiol, and most contain 35 j.1g or less.
In a few COCs, inert placebo pills have been replaced by tablets containing iron. These have the suix Fe added to their name. In addition, Beyaz has a form of folate-levomefolate calcium-within both its active and placebo pills.
With COCs termed monophasic piLs, the progestin dose remains constant throughout the cycle. In others, the dose frequently is varied, and term biphasic, triphasic, or quadriphasic piL is used depending on the number of dose changes within the cycle. In some formulations, the estrogen dose also varies. In general, phasic pills were developed to reduce the total progestin content per cycle without sacrificing contraceptive eicacy or cycle control. he theoretical advantage of a lower total progesterone dose per cycle, however, has not been borne out clinically (Moreau, 2007). Cycle control also appears to be comparable among mono-through triphasic pills (van Vliet, 2011a,b,c).
Hormones are taken daily for a specified time (21 to 81 days) and then replaced by placebo for a speciied time (4 to 7 days), which is called the "pill-free interval." During these pill-free days, withdrawal bleeding is expected.
With the trend toward lower estrogen doses to minimize side efects, follicular development and ovulation may occur. To counter this, the active-pill duration in some formulations is extended to 24 days. In comparison, these 24/4 regimens perform similarly to higher-estrogen-dose 21/7 regimens (Anttila, 2011; Marr, 2012).