From the Guidelines
Hormonal contraceptives, including tricyclic contraceptives, work primarily by preventing ovulation, thickening cervical mucus to block sperm entry, and thinning the endometrial lining to prevent implantation, and are indicated for pregnancy prevention as well as treatment of various conditions such as dysmenorrhea, menorrhagia, and acne. These medications contain synthetic versions of estrogen and/or progestin that manipulate the body's hormonal environment to prevent pregnancy. Common hormonal contraceptives include combined oral contraceptives (COCs) like Yaz, Ortho Tri-Cyclen, or Loestrin (containing both estrogen and progestin) 1, progestin-only pills (POPs) like Micronor (0.35mg norethindrone daily), injectable contraceptives like Depo-Provera (150mg medroxyprogesterone acetate every 3 months), implants like Nexplanon (68mg etonogestrel implant effective for 3 years), hormonal IUDs like Mirena (52mg levonorgestrel, effective for 5-7 years), and patches like Xulane (releasing 150mcg norelgestromin and 35mcg ethinyl estradiol daily). Some key points to consider when prescribing hormonal contraceptives include:
- Patient preference and medical history
- Contraindications such as history of thromboembolism, estrogen-dependent cancers, uncontrolled hypertension, migraine with aura, and liver disease
- The importance of avoiding estrogen-containing methods in women over 35 who smoke or have cardiovascular risk factors, while progestin-only methods are often safer alternatives for these patients 1
- The need for back-up contraception when switching from another contraceptive method, such as an IUD, to a combined hormonal contraceptive 1. The indication to prescribe tricyclic contraceptives, such as Ortho Tri-Cyclen, would be for patients who require a hormonal contraceptive for pregnancy prevention or treatment of conditions like acne, dysmenorrhea, or menorrhagia, and have no contraindications to estrogen-containing methods.
From the FDA Drug Label
Combination oral contraceptives act by suppression of gonadotropins. Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cervical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which reduce the likelihood of implantation)
The indication to prescribe hormonal contraceptives, such as combination oral contraceptives, is for contraception. They work by:
- Suppressing gonadotropins, which leads to inhibition of ovulation
- Changing the cervical mucus, making it more difficult for sperm to enter the uterus
- Altering the endometrium, reducing the likelihood of implantation 2
From the Research
Mechanism of Action of Hormonal Contraceptives
- Hormonal contraceptives work by inhibiting ovulation and altering the cervical mucus to prevent sperm penetration 3
- The primary mechanisms of action for combined oral contraceptives and progestin-only methods are ovulation inhibition and changes in cervical mucus 3
- Hormonal methods, particularly low-dose progestin-only products and emergency contraceptive pills, may also affect the endometrium, but there is no evidence to suggest that they prevent implantation 3
Indications for Prescribing Hormonal Contraceptives
- Hormonal contraceptives are commonly prescribed for contraception, but they may also be used to treat endometriosis, dysmenorrhea, and menstruation-associated symptoms 4, 5
- Continuous or extended-cycle use of combined hormonal contraceptives may be beneficial for women who want to avoid menstruation, as it can improve compliance, satisfaction, and reduce menstrual symptoms 5
- Hormonal contraceptives may be prescribed for women who do not desire to become pregnant and want to control endometriosis/adenomyosis-related symptoms 4
Types of Hormonal Contraceptives
- Combined oral contraceptives (COCs) contain both estrogen and progestin, and are available in different regimens, such as 21/7 and 24/4 6
- Progestin-only methods, such as progestin-only pills and intrauterine devices, are also available and may be used for contraception and to treat endometriosis/adenomyosis 4, 3