This document discusses oral contraceptives, including their definition, types, mechanisms of action, effects, and pharmacokinetics. The two main types are combined oral contraceptives containing estrogen and progestogen, and progestogen-only pills. Combined pills prevent pregnancy primarily by suppressing ovulation and thickening cervical mucus. Progestogen-only pills work mainly by changing cervical mucus. Common side effects include nausea, weight gain, and changes in menstruation. Oral contraceptives are metabolized in the liver and can interact with certain drugs like antibiotics. Emergency contraception is also discussed.

1. ORALCONTRACEPTIVES
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. Type of oral
contraceptives
The combined
pill
The
progestogen
only pills

4. 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).

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

6.  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.

7.  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.

8. MODE 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

9.  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.

11. 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.

12. 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.

13.  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.

14.  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.

15.  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.]

16. 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.

18. THE PROGESTOGEN-ONLY PILL
 The drugs used in progestogen only pills include
norethisterone, levonorgestrel or ethynodiol.
 The pill is taken daily without interruption.

19. 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

20. 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.

21.  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.

23. 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.

24.  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.

25. 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

26. 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).

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