I. Background info

  1. Probability of pregnancy w/unprotected intercourse is 15% 3d before ovulation, 30% 1-2d before ovulation, 12% on day of ovulation (Contracep. 57:363, 1998--Med. Lett.)
  2. Unclear how postcoital estrogen (+/- progestin) prevents pregnancy; various mechanisms have been suggested

II. Guidelines for use

  1. All methods for use <72h post-coitus (except Ulipristal; see below)
  2. Should have no contraindications to estrogens or progestins.
  3. Should do pregnancy test to r/o preexisting pregnancy
  4. Side f/x similar in all: nau, breast tenderness, menstrual irreg. (next period comes early or late)
  5. May require antiemetic; if vomit a dose, should repeat the dose
  6. Note that emergency contraception may make the next menstrual cycle come earlier and cause the next 1-2 menses to be longer than usual for the patient (Contraception 73:376, 2006--JW)
  7. Efficacy may be reduced in women with BMI > 30 kg/m2
  8. Expect menses no more than 1wk delayed from regular schedule and if not, need to rule out pregnancy

III. Specific regimens

  1. "Yupze" method:
  1. (100ug ethinylestradiol + (500ug levonorgestrel or 1000ug norgestrel ) given twice, 12h apart
  2. 2.6% preg rate
  3. Most freq & severe side f/x--70% have nausea
  4. Avaiblable as "Preven Emergency Contraceptive Kit" (ethinyl estradiol 50ug/levonorgestrel 0.25mg; take 2 PO Q12h x 2, starting ASAP after unprotected intercourse; may repeat either dose if vomit < 1h after taking)
  1. Norgestrel alone--more effective than Yupze method!
  1. 1955 women randomized to the 2-drug Yupze method as above vs. levonorgestrel alone (500ug Q12h x 2); at 1wk f/u, pregnancy incidence was 1.1% with levonorgestrel alone vs. 3.2% in Yupze group, suggesting pregnancy reduction rates of 85% in levonorgestrel group and 57% in Yupze group; fewer GI side f/x in levonorgestrel-only group (Lancet 352:428, 1998--AFP) (I wonder whether the higher efficacy w/levonorgestrel only might have been due to fewer women vomiting up the meds--ER)
  2. Available in US as "Plan B"--Levonorgestrel 0.75mg, 1 PO Q12h x 2
  3. Plan B "One-Step" (levonorgestrel 1.5mg x 1)-Approved by FDA 7/09
  1. From JWWH 2:62, 1997: Take # of tabs listed w/in 72h of unprotected sex, and the same # of tablets 12h later (except for Ovrette, see below). Give antinausea meds 1h before each dose.
  1. Ovral: 2 white pills
  2. Lo-Ovral: 4 white pills
  3. Levlen: 4 orange pills
  4. Nordette: 4 orange pills
  5. Triphasil: 4 yellow pills
  6. Trilevlen: 4 yellow pills
  7. Alesse: 5 pink pills
  8. Ovrette (progestin-only): 20 tabs w/in 48h of unprotected sex, then 20 more in 12h
  1. Ulipristal acetate (Ella)
    1. Mixed progestersone agonist/antagonist
    2. Postpones follicular rupture, delaying ovulation; may also inhibit implantation of a fertilized ovum
    3. Can reduce risk of pregnancy if taken up to 5d after unprotected intercourse/contraceptive failure
    4. Given as a single 30mg dose up to 120h after unprotected intercourse/contraceptive failure; may repeat dose if vomiting within 3h
    5. In clinical trials reduced pregnancy rate from an expected 5.5% to an observed 2.2% when taken 48-120h after unprotected intercourse
  2. Mifepristone (RU486)
  1. Probably most effective regimen at preventing preg. (0% preg rate)
  2. Not available in US as of 1999
  3. Dosing: traditionally, 600mg x 1; however, doses as low as 10mg may be effective (Lancet 353:697, 1999--AFP)
  4. 1000 women < 72h out from unprotected intercourse randomized to Yupze regimen vs. mifepristone 100mg; if no period by predicted date, pregnancy test given.  Pregnancy rate was 3.6% in Yupze group and 0.6% in mifepristone group; mifepristone group also had less nausea and vomiting (BJOG 109:553, 2002--JW)
  1. Danazol 600mg x2 12h apart-INEFFECTIVE
  1. 7% preg. rate; same as expected without any Tx!
  1. Comparisons between different regimens
    1. In a randomized trial of 1300 women presenting < 120h after unprotected intercourse and negative urine hCG, comparing the following regimens; The pregnancy rates were not sig. diff. in any of the groups; levonorgestrel recipients had more bleeding (Lancet 360:1803, 2002--AFP)
      1. Mifepristone 10mg x 1
      2. Levonorgestrel 1.5mg x 1
      3. Levonorgestrel 0.75mg Q12h x 2