Contraception, Oral, Injections, & Implants

Key Features

General Considerations

• Unintended pregnancies are a worldwide problem but disproportionately impact developing countries

• Studies estimate that 40% of the 213 million pregnancies that occurred in 2012 were unintended

• Globally, 50% ended in abortion, 13% ended in miscarriage, and 38% resulted in an unplanned birth

• Primary care providers need to educate their patients about the benefits of contraception and to provide them options that are appropriate and desirable

Treatment

Medications

Oral contraceptives

• Combination pills

  • Have a theoretical failure rate of only 0.3% if taken absolutely on schedule but a typical use failure rate of 8%

  • Primary mode of action is suppression of ovulation

  • Pills can be started on the first day of the menstrual cycle, on the first Sunday after the onset of the cycle, or on any day of the cycle

    • If started on any day other than the first day of the cycle, a backup contraceptive method should be used

    • The combination pill is taken daily for 21 days, followed by 7 days of placebos or no medication, and this schedule is continued for each cycle

  • Pills are typically packaged in 21- or 28-day cyclic regimens but may be taken continuously to allow the user to decide if and when she has a withdrawal bleed

  • Studies have not shown any significant risk from long-term amenorrhea for patients taking this continuous oral contraceptive regimen

Benefits

• There are many noncontraceptive advantages to oral contraceptives

  • Menstrual flow is lighter

  • Decreased risk of ovarian and endometrial cancer

  • Improvement in acne

  • Dysmenorrhea, pain with ovulation and postovulatory aching are relieved for most women

  • Functional ovarian cysts generally disappear with oral contraceptive use, and new cysts do not occur

  • There is also a beneficial effect on bone mass

• Selection

  • Any of the "low-dose" combination oral contraceptives (containing 35 mcg or less of ethinyl estradiol or 3 mg of estradiol valerate) are suitable for most women

  • There is some variation in potency of the various progestins in the low-dose pills, but this variation results in essentially no clinically significant differences for most women

  • Women who have acne or hirsutism may benefit from use of one of the pills containing the third-generation progestins, desogestrel or norgestimate, since they are the least androgenic

  • The low-dose oral contraceptives commonly used in the United States are listed in Table 18–2

• Drug interactions

  • Drugs that interact with oral contraceptives potentially decreasing their efficacy include

    • Phenytoin

    • Phenobarbital (and other barbiturates)

    • Primidone

    • Topiramate

    • Carbamazepine

    • Rifampin

    • St. John's wort

  • Women taking these drugs should use another means of contraception for maximum protection

  • Antiretroviral medications, specifically ritonavir-boosted protease inhibitors, may significantly decrease the efficacy of combined oral contraceptives, and the concomitant use of oral contraceptives may increase the toxicity of these antiretroviral agents

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