Oral contraceptives

the presentation includes a definition of oral contraceptives, type of oral contraceptives, detail description of both types with its mode of action and potential beneficial and unwanted effects also include pharmacokinetics of oral contraceptives and knowledge of emergency contraceptives

1. ORAL CONTRACEPTIVES BY: PRIYA SHUKLA SSR COLLEGE OF PHARMACY DEPARTMENT : PHARMACOLOGY GUIDE: Dr. Chirag .A. Patel

2. Definition Oral contraceptives are medicines taken by oral route to help prevent pregnancy. They are also known as “birth control pills”.

3. The combined pill (combinations of and estrogen with a progestogen) Formulations may be : 1 . Monophasic (each tablet contains a fixed amount of estrogen and progestin); 2. Biphasic (each tablet contains a fixed amount of estrogen, while the amount of progestin increases in the second half of the cycle); or 3. Triphasic (the amount of estrogen may be fixed or variable, while the amount of progestin increases in 3 equal phases).

4. The estrogen in most combined preparations (second-generation pills) is ethinylestradiol , although a few preparations contain mestranol instead.

5. The estrogen content is generally 20-50μg of ethinylestradiol or its equivalent, and a preparation is chosen with the lowest estrogen and progestogen content that is well tolerated and gives good cycle control in the individual woman.

6. This combined pill is taken for 21 consecutive days followed by 7 pill-free days, which causes a withdrawal bleed. Normal cycles of menstruation usually come fairly soon after discontinuing treatment.

7. M ode of action estrogen inhibits secretion of FSH via negative feedback on the anterior pituitary, and thus suppresses development of the ovarian follicle progestogen inhibits secretion of LH and thus prevents ovulation; it also makes the cervical mucus less suitable for the passage of sperm

8. estrogen and progestogen act in concert to alter the endometrium in such a way as to discourage implantation. They may also interfere with the coordinated contractions of cervix, uterus and fallopian tubes that facilitate fertilisation and implantation.

9. Common adverse effects weight gain, owing to fluid retention or an anabolic effect, or both mild nausea, flushing, dizziness, depression or irritability skin changes (e.g. acne and/or an increase in pigmentation) amenorrhoea of variable duration on cessation of taking the pill.

10. POTENTIAL ADVERSE EFFECTS Cardiovascular: Although rare, the most serious adverse effect of oral contraceptives is cardiovascular disease, including thromboembolism , thrombophlebitis , hypertension, increased incidence of myocardial infarction, and cerebral and coronary thrombosis. These adverse effects are most common among women who smoke and who are older than 35 years, although they may affect women of any age.

11. Carcinogenicity: Oral contraceptives have been shown to decrease the incidence of endometrial and ovarian cancer. Their ability to induce other neoplasms is controversial. The production of tumors of the liver that may rupture and hemorrhage is rare.

12. Metabolic: Abnormal glucose tolerance (similar to the changes seen in pregnancy) is sometimes associated with oral contraceptives. Weight gain is common in women who are taking the nortestosterone derivatives.

13. Serum lipids: The combination pill causes a change in the serum lipoprotein profile: Estrogen causes an increase in HDL and a decrease in LDL (a desirable occurrence), whereas progestins may negate some of the beneficial effects of estrogen. [Note: The potent progestin norgestrel causes the greatest increase in the LDL:HDL ratio. Therefore, estrogen -dominant preparations are best for individuals with elevated serum cholesterol.]

14. Beneficial effects The combined pill markedly decreases menstrual symptoms such as irregular periods and intermenstrual bleeding. Iron deficiency anaemia and premenstrual tension are reduced, as are uterine fibroids and functional cysts of the ovaries.

15. The progestogen -only pill The drugs used in progestogen only pills include norethisterone , levonorgestrel or ethynodiol . The pill is taken daily without interruption.

16. mode of action The mode of action is primarily on the cervical mucus, which is made inhospitable to sperm. The progestogen probably also hinders implantation through its effect on the endometrium and on the motility and secretions of the fallopian tubes

17. Potential beneficial and unwanted effects Progestogen-only contraceptives offer a suitable alternative to the combined pill for some women in whom estrogen is contraindicated, and are suitable for women whose blood pressure increases unacceptably during treatment with estrogen .

18. However, their contraceptive effect is less reliable than that of the combination pill, and missing a dose may result in conception. Disturbances of menstruation (especially irregular bleeding) are common.

19. Pharmacokinetics of oral contraceptives Combined and progestogen -only oral contraceptives are metabolised by hepatic cytochrome P450 enzymes. Because the minimum effective dose of estrogen is used (in order to avoid excess risk of thromboembolism ), any increase in its clearance may result in contraceptive failure, and indeed enzyme-inducing drugs can have this effect not only for combined but also for progesterone-only pills.

20. Such drugs include rifampicin and rifabutin , as well as carbamazepine , phenytoin , griseofulvin and others. Broad-spectrum antibiotics such as amoxicillin can disturb Enterohepatic recycling by altering the intestinal flora, and cause failure of the combined pill. This does not occur with progesterone-only pills.

21. Ormeloxifene Ormeloxifene is a selective estrogen receptor modulator (SERM). Marketed as Centchroman , Centron , or Saheli , it is pill that is taken once per week. Ormeloxifene is legally available only in India

22. POSTCOITAL (EMERGENCY) CONTRACEPTION Oral administration of levonorgestrel , alone (1.50 mg usually) or combined with estrogen , is effective if taken within 72 hours of unprotected intercourse, repeated 12 hours later. Nausea and vomiting are common. (replacement tablets can be taken with an antiemetic such as domperidone ).

23. A single dose of mifepristone has also been used for emergency contraception.