levonorgestrel (Norplant)

Introduction

Tradename: Norplant.

Indications

• contraceptive: 6 implants subdermal every 5 years
• emergency (post coital) contraceptive
• excessive menstrual bleeding in women who use intrauterine contraception

Dosage

Capsule: (subdermal implantation: 36 mg)

Each Norplant silastic capsule releases 80 ug/day for 6-18 months, after which 25-30 ug/day is released & maintained for a total effective duration of < 5 years.

Mirena: intrauterine device (see levonorgestrel-releasing IUD)

Adverse effects

• common (> 10%)
  • prolonged menstrual flow, spotting
• less common (1-10%)
  • amenorrhea, irregular menstrual cycles, scanty bleeding, pain or itching at implant site, headache, nervousness, breast discharge, myalgia, leukorrhea, vaginitis, nausea, dizziness, dermatitis, acne, change in appetite, weight gain
• uncommon (< 1%)
  • infection at site of implantation

Drug interactions

• carbamazepine
• phenytoin
• rifampin

• drug interaction(s) of beta-adrenergic receptor antagonists with oral contraceptives
• drug interaction(s) of NSAIDs with oral contraceptive

Mechanism of action

• prevents ovulation or fertilization by altering the fallopian tubal transport of sperm or ova
• not effective once implantation has occurred or the woman is already pregnant

More general terms

• norgestrel (Ovrette)

More specific terms

• morning after pill

Additional terms

• levonorgestrel-releasing intrauterine system (Mirena, LNG-IUS, LILETTA, Skyla)

Component of

• estradiol/ethinyl estradiol/levonorgestrel
• contraceptive/estradiol/ethinyl estradiol/levonorgestrel
• Seasonique (LoSeasonique)
• estradiol/levonorgestrel
• ethinyl estradiol/levonorgestrel (Jolessa, Lessina, Chateal EQ)
• post coital contraception (Plan B, morning after)
• Climara Pro
• Levlen, Levora, Nordette
• Alesse
• Tri-Levlen, Triphasil
• Seasonale
• Lybrel (ethinyl estradiol, levonorgestrel)

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=13109