contraception Flashcards
MoA for COCP causing an increased risk of VTE
Exogenous oral oestrogen causes hypercoagulability. VTE risk depends on dose of oestrogen and type of progestogen used. Other pre-existing patient risk factors will also increase the risk.
- Increases plasma fibrinogen
- Increases the activity of coagulation factors (VII and X)
- Anti-thrombin III decreased (inhibitor of coagulation)
- Platelet activity is enhanced with accelerated aggregation.
Progestins used in COCP
First generation: Norethisterone
Second generation: Levonorgestrel
Third generation: Desogestrel, gestodene, norgestimate
Fourth generation: Drospirenone,nomengestrel acetate,cyproterone acetate
First and second generation Progestogens increase RR 3.0 for VTE 15 cases per year of use / 100 000 women
Third/4th gen: RR 5.0 25 cases per year of use / 100 000 women.
Androgenic progestins have been found to antagonize to some degree the effects of ethinylestradiol on coagulation. As a result, more androgenic progestins, like levonorgestrel and norethisterone, may oppose the procoagulatory effects of ethinylestradiol and result in a lower increase in risk of VTE. Conversely, progestins that are less androgenic, like desogestrel as well as with progestins that are antiandrogenic, like drospirenone and cyproterone acetate have a higher VTE risk.
MoA for COCP as contraceptive
Inhibits ovulation, thickens cervical mucus.
Progesterone is primarily responsible for preventing pregnancy. The main mechanism of action is the prevention of ovulation; they inhibit follicular development and prevent ovulation. Progestogen negative feedback works at the hypothalamus to decrease the pulse frequency of the gonadotropin-releasing hormone. This, in turn, will reduce the secretion of follicle-stimulating hormone (FSH) and decreases the secretion of luteinizing hormone (LH). If the follicle isn’t developing, there is no increase in the estradiol levels (the follicle makes estradiol). The progestogen negative feedback and lack of estrogen positive feedback on LH secretion stop the mid-cycle LH surge. With no follicle developed and no LH surge to release the follicle, ovulation is prevented.
Novel male contraceptives
Hormonal gel – progestogen (segesterone acetate/Nestorone) and testosterone, gel applied once daily. Phase 2 trial results presented orally in 2024. 86% reached a sperm concentration <1million/ml by 15 weeks. Most of these suppressed by 8 weeks.
Hormonal injection – IM progestogen and testosterone. Appeared to be an effective option with 96% of men reaching a conc <1million/mL at 24 weeks. 1.5/100 user unplanned pregnancy rate. But study discontinued early due to side effect profile particularly mood disorders.
Vaccination – immunotherapy for contraception. Anti-gonadotrophin hormone vaccine, sperm antigen vaccine. Issues are reversibility, safety and delivery.
ECP options
Copper IUCD, can be inserted up to 5 days post UPSI. Does not reduce in efficacy the longer the delay in insertion. MoA – inhibition of fertilisation as copper ions are sperm toxic. If fertilisation does occur/has occurred then it prevents implantation due to inflammatory endometrium.
ECP – MOA is delayed or inhibited ovulation by negative feedback on HPO axis and preventing LH surge
1. Levonorgestrel 1.5mg tablet – orally.
Take as soon as possible and within 72hours of UPSI.
Double dose in those with BMI >30kg/m2 (reduced effectiveness in this group)
2. Ulipristal acetate (UPA) 30mg tablet – orally.
More effective than LNG, can be taken up to 120 hours (5 days) of UPSI. Efficacy can be impaired with by concurrent hormonal contraception – so delay starting.
Yaz and Yasmin
Yaz - 20mcg EE and drosperinone
Yasmin - 30mcg EE and drosperinone
Drosperinone is a progestin, anti-androgen and anti-mineralocorticoid (similar but more potent than spironolactone).
USed for PMDD.
Hirsutism, acne.
However limited evidence showing clinically significant advantages over other standard COCPs.
Drosperinone is an analogue of spironolactone so caution required in those with renal impairment and those on K+ sparing drugs as inc risk of hyperkalaemia.
Cyproterone acetate containing COCPs
Diane/Estelle
Anti-androgen and progestin.
Useful for hirsuitism, acne.
Increased VTE risk so not usually first line.
Progestin only pills
Type of contraceptive: hormonal progesterone only pill
MOA: Microlut and Noriday – cervical mucus thickening, thins endometrium and prevents implantation (66% get inhibition of ovulation too). Cerazette – inhibition of ovulation as well as above.
Failure rate: 9% actual, improves if older, breast feeding, worsens if weight >70kg
Hx/Ix prior to commencing: Good pill taker, noriday must be taken within 3hours every day, cerazette within 12 hours, personal history that would prevent using, BMI and BP good practice but not required.
Contraindications: pregnancy, undiagnosed abnormal vaginal bleeding, breast cancer, GTD with rising hCG, severe arterial disease, prev ectopic, acute porphyria.
Advantages: used while breastfeeding, may help with PMS, easily accessible, easily reversible.
Side effects/disadvantages: irregular bleeding, increased risk of ectopic, worsening acne, breast tenderness, headaches, increased risk of benign functional cysts, less effective, must remember to take at the same time each day. If miss a pill alternative contraception for 2 days with noriday, 7 days with cerazette.
VTE: no increased risk.
Risks if pregnancy occurs: ectopic.
Follow up: six monthly
Reversibility: immediate
COCP side effects and management
Cochrane review found that second and third gen progestogens were preferred to norethisterone (first gen), across all acceptability indices they measured including effectiveness, discontinuation rates, reasons dor dicontinuation, cycle control and side effects.
