Week 4: Mechanism of contraceptives Flashcards
1
Q
Synthetic progestins
A
- Estranes -1st gen-C 19
- low pro gestational activity
- 19-nortestosterone, norethindrone, ethynodiol diacetate - Gonanes- 2nd gen- C21
- norgestrel, desogestrel, norgestimate
- increases progestin activity
- e.g. Implant and vaginal ring have etonogestrel, which is the active metabolite of desogestrel
- skin patch has norelgestromin, the active metabolite of norgestimate+ethinyl estradiol
2
Q
Progestin only contraceptives
A
- method of delivery
- pill: norethindrone, levonorgestrel
- Injections: Depo-medroxyprogesterone
- implant: nexplanon with etonogestrel - Mechanism
- negative feedback to decrease GnRH, LH and FSH, prevents mid cycle surge of LH. Pill is less effective at inhibiting ovulation
- produces thick cervical mucus to reduce sperm penetration - Drawbacks/ side effects
- pill: same time everyday.
- spotting, breakthrough bleeding
- decrease menstrual flow, amenorrhea, irregular bleeding
3
Q
Mechanism of COCs and side effects
A
- mechanism
- negative feedback to decrease GnRH, LH and FSH, prevents mid cycle surge of LH
- produces thick cervical mucus to reduce sperm penetration
- prevents fertilization by altering transport of sperm and ovum in fallopian tubes - side effects
- nausea, vomiting, chloasma, HTN, thromboembolism, gallstone formation
- due to increased synthesis of blood clotting factors
4
Q
Contraindications for COCs
A
- Pregnancy
- Breast cancer
- Hepatic disease
- Undiagnosed genital bleeding
- Uncontrolled blood pressure
- Thromboembolic diseases
- Obesity (risk of VTE)
- Cardiovascular disease
- Heavy smokers: > 35 yo
- Lactating mother (may be given after 6 months)
5
Q
Indications for progestin only contraceptives
A
- heavy smokers, >35 yo
- lactating mother. progestins don’t inhibit prolactin action and don’t interfere with milk production
6
Q
Drug interactions with COCs
A
-antiepileptics (phenytoin)
-rifampin
-St. John’s wrot
These induce CYP, and increase metabolism of estrogen/progestin
