Pharmacology of Gonadal Hormones 6

Question 1

Describe the regulation of female gonadal hormone secretion during the reproductive cycle.

Answer 1

See image.

Question 2

What are the common mechanism of oral contraceptives?

Answer 2

• Most are estrogen and progestin, various regimens
• Some are progestin only
• Mechanisms:
  
  • pituitary suppression, preventing ovulation
  • abnormal endometrium, preventing implantation
  • abnormal cervical mucus, impeding sperm

Question 3

Describe the make up and regimen for estrogen/progestin combination oral contraceptives.

Answer 3

• Components
  
  • estrogen component is usually ethinyl estradiol
  • progestin component is often norethindrone or levonorgestrel
• Regimen
  
  • combination for 21 days, followed by no treatment for 7 days
    
    • results in withdrawal bleeding
  • multiple regimens now availaible
    
    • more closely mimics endogenous hormone ratios
    • decrease the total hormone dose/cyle
    • shorten hormone-free intervals (less frequent menses)
  • Transdermal patch
    
    • estrogen and progestin combination
    • replace once/week

Question 4

What are some progestin only contraceptives?

Answer 4

• “Minipill”
  
  • lower dose
  • higher failure rate
  • more irregular menses
• Implants
  
  • under skin or intrauterine device
  • slow release, for up to 10 years

Question 5

Describe the methods for emergency (postcoital) contraception.

Answer 5

• Higher doses of estrogen, progestin, or both taken within 72 hrs of unprotected intercourse
  
  • Preven - ethinyl estradiol and levonorgestrel
  • Plan B - levonorgestrel
• First dose taken within 72 hrs, second 12 hrs later
• Plan B One Step - ouble dose within 72 hrs
• Ella - ulipristal
  
  • non-hormonal agent that blocks hormone effects
  • taken up to 5 days after intercourse

Question 6

What is the use of mefipristone (RU-486)?

Answer 6

• Antiprogestin
  
  • more potent on progestin than glucocorticoid receptors
• Inhibits follicle maturation, ovulation, and implantation
• Prostaglandin is given 48 hrs after mifepristone to increase myometral contraction and expulsion of the blastocyst