Contraceptives Flashcards
What is conception?
fusion of the sperm & ovum to produce a new organism
What is contraception?
preventing conception
- can be achieved by intercepting conception process from gametogenesis in the gonads to endometrial implantation of fertilized ovum
What is the function of oral contraceptives?
prevent ovulation
How can sperm be destroyed?
vaginal spermicides
How can the union of sperm and ovum be mechanically prevented?
condoms, cups, loops
What is the future of contraceptives?
Oral drugs to suppress spermatogenesis are being developed.
A vaccine to neutralize (HCG) has been developed and tried
Name 8 methods of birth control?
- Pill (combined);
- Minipill (progestogens only);
- Intrauterine devices (IUDs);
- Diaphragms
- Condoms
- Condoms plus foam
- natural family planning (basal body temperature, cervical mucous method);
- Sterilization (tubal ligation for women, vasectomy for men)
- all are at least 97% effective
Name types of oral contraceptive formulations?
- Oestrogen-progestogens - Combinations (combination pill)
- Sequential oestrogen-progestogen preparations.
- Continuous low-dosage progestogen preparations (minipills)
Describe the administration of oestrogen-progesterone combinations?
- administered in a single daily dose from day 5 to day 25 of the menstrual cycle (21 days)
- Withdrawal bleeding occurs within 3 to 4 days on completion of the course
- In between there are 7 pill free days and course started on 5th day of next cycle
- almost 100% effective
Describe the administration of sequential oestrogen-progestogen preparations?
- Pills are administered from day 5 to day 25 of the menstrual cycle (21 days).
- From day 5 to day 20 a single daily pill containing oestrogen alone is administered, followed by a single oestrogen-progestogen combination pill from day 21 to 25.
- Again there are 7 pill free days during which withdrawal bleeding occurs.
- The pills are packed in sequential order for ease of administration
How do sequential oestrogen-progestogen preparations work?
Inhibition of ovulation is mainly due to oestrogen, progestogen is added to ensure satisfactory bleeding
Describe the administration of low-dosage progestogens preparations?
- They contain a progestogen alone (norethindrone; norgestrel).
- They are taken daily continually.
- This method is less effective than the combination or sequential methods
When are low dosage progestogens preparations used?
as alternative when oestrogen is contraindicated (specially in cardio-vascular, hepatobiliary, cancer and some metabolic disorders)
Describe the mode of action for COC?
- The hypothalamic gonadotrophin releasing hormone (FSH-LH-RH) is inhibited by oestrogen, which leads to suppression of FSH and LH release from anterior pituitary.
- A direct inhibiting effect on the pituitary secretion of gonadotrophins is also likely. - The suppression of FSH and LH caused by oestrogen is enhanced by progestogen
- There are also changes in the motility and secretions of the fallopian tubes which presumably interfere with fertilisation
Describe the mode of action of low-dose pills?
1, The low-dose pills given continually alter the endometrium and put it out of phase with ovulation.
- The viscosity of the cervical mucus is increased making it less penetrable to sperms.
- There is no disruption of the cycle and ovulation continues.
- Menstruation occurs, but length of the cycle and duration of bleeding are variable
How do COC affect the body to prevent conception?
- COC act mainly by preventing ovulation by suppressing the release of gonadotrophins
- Inhibit implantation by
- ↓ endometrial proliferation → no ovum can be embedded
- ↓ secretion & peristalsis in fallopian tubes → hinder transport - Inhibit fertilization
- ↑ viscosity of cervical secretion → no sperm pass
Describe the efficacy of oral contraceptives?
- Forgetting to take one tablet during the 21 day course of the combination or sequential pills rarely leads to ovulation.
- A pill missed early in the cycle is more likely to result in pregnancy, than a pill missed later.
- If there has been many omissions during the cycle, it is advisable to use a barrier method in addition.
Describe the use of contraceptives?
It is advisable that additional contraceptive means be used during the first two months of medication.
- Normal ovulatory cycle follows within 1 to 3 months of stoppage of medication.
- Thus offers a safe and reversible contraception.
Describe the therapeutic uses of contraceptives?
- The combination products have been employed in endometriosis, when severe dysmenorrhea is the major symptom
- Suppression of ovulation is followed by painless periods. - In cases of functional sterility suppression of ovulation for 3 to 6 months may increase the chances of conception
- rebound effect
What are the absolute contraindications of contraceptive use?
- Thromboembolic or arterial disease
- Diabetes mellitus
- Hyperlipidaemia
- Liver disease
- Breast and uterine carcinoma
- Undiagnosed vaginal bleeding
- Pregnancy
What are the relative contraindications of contraceptive use?
Hypertension
Epilepsy
Depression
What are medications that cause contraceptive failure: ( i.e. impairing absorption & CYT P450 Inducers)?
- Antibiotics that interfere with normal GI flora
→ ↓absorption & ↓enterohepatic recycling → ↓its bioavailability. - Microsomal Enzyme Inducers → ↑ catabolism of OC. (Phenytoin , Phenobarbitone, Rifampin)
What are medications that ↑ COC toxicity: (i.e. CYT P450 inhibitors)?
Microsomal Enzyme Inhibitors; ↓metabolism of OC → ↑ toxicity. (Acetominophen, Erythromycin, SSRIs.)
Describe how COC can interact with other drugs?
COC alter clearance (↓) of some drugs hence ↑ toxicity
WARFARIN, Cyclosporine, Theophyline
