This document presents a summary of screening models used to evaluate antifertility drugs. It discusses several classes of antifertility drugs and their mechanisms of action, including GnRH antagonists, estrogen antagonists like clomiphene and aromatase inhibitors, and gonadotropins. It also describes in vivo and in vitro screening methods to assess effects on ovulation, implantation, and endometrial growth. Key in vivo tests include HCG-induced ovulation in rats, uterine weight assays in rabbits, and prevention of abortion in oxytocin-treated pregnant rabbits. Receptor binding assays and tests like the McGinty test are discussed as in vitro approaches.

1. Presentation on screening model of
antiaesthmatic drugs
FACULTY OF PHARMACY
Presented by: Guided by:
Mohd Fahad Dr.Anuradha Mishra
M. Pharm Ist Year
(Pharmacology)
INTEGRAL UNIVERSITY

2. Antifertility drugs are chemical substances
which suppress the action of hormones
that promote pregnancy.
These drugs actually reduce the chances of
pregnancy and act as a protection.
Antifertility drugs are made up of
derivatives of synthetic progesterone or a
combination of derivatives of estrogen and
progesterone.

4. CLASSIFICATIONS—
GnRH antagonist:
Either Gonadotropin-releasing hormone (GnRH) or any Gonadotropin-releasing
hormone agonist (i.e. Lupron) may be used. GnRH stimulates the release of
gonadotropins (LH and FSH) from the anterior pituitary in the body.
Oestrogen antagonists:
Fertility medication inhibiting the effects
of estrogen includes Clomiphene and Aromatase inhibitors.
Clomiphene:-
Clomiphene (trademarked as Clomid) is a selective estrogen receptor
modulator (SERM). It is the most widely used fertility drug. It is used as an ovarian
stimulator by inhibiting the negative feedback of estrogen at the hypothalamus. As the
negative feedback of estrogen is inhibited, the hypothalamus secretes GnRh which in
turn stimulates the anterior pituitary to secrete LH and FSH which help in ovulation.

5. Aromatises inhibitors----
Although primarily a breast cancer treatment, aromatase
inhibitors can also work as fertility medication, probably through a
mechanism similar to clomiphene.
Gonadotropins----
Gonadotropins are the hormones in the body that normally stimulate
the gonads (testes and ovaries). For medication, they can be extracted
from urine or by genetic modification.
For example, the so-called menotropins consist
of LH and FSH extracted from
human urine from menopausal women.] FSH and FSH analogues are
mainly used for ovarian hyperstimulation as well as reversal
of anovulation.

6. Human chorionic gonadotropin
Human chorionic gonadotropin (hCG) is normally
produced during pregnancy. However, it can also replace
LH as an ovulation inducer.
Other
hMG is a medication containing a follicle-stimulating
hormone (FSH) and a lutenizing hormone (LH).

7. Methods for female
Female antifertility agents might be acting through
following machanism:-
1.Inhibition of ovulation.
2.Prevention of fertilization.
3.Interference with transport of ova from oviduct to
endometrium of the uterus.
4. Interference with the implantation of fertilized
ovum.
5.Distraction of early implanted embryo.

8. In vivo methods
• Vaginal opening
• Assay for water uptake
• Four –day uterine weight assay
• Vaginal cornification
• Chick oviduct method
 Anti estrogenic activity
 Antagonism of physiological effect of estrogen.
• Aromatase inhibitor

9. CONT....
• Antiovulatory Activity :
1. HCG-induced Ovulation in Rats.
2. Cupric Acetate-induced Ovulation In Rabbits
Progestational activity
• Pregnancy maintenance test.
• Prolifration of uterine endometrium in
estrogen-primed rabbit test

10. IN VIVO MODEL
• PREGNANCY MAINTENANCE TEST
• PRINCIPLE:-PROGESTERONE IS RESPONSIBLE FOR THE MAINTENANACE FOR THE
PREGNANCY.THIS PRINCIPLE IS USED FOR THE SCREENING OF PROGESTATIONAL
COMPOUND.
• PROCEDURE-
• Ovariectomy is done on day 5/10/15 of pregnancy in diff group of pregnant
rats
the animals are treated with diff test and standard drug
The average of living fetuses at the end of the experiment is compared with
standard and control group.
NOTE-The ED50 progesterone is 5mg/day in rat and less the 0.5mg/day in mouse

11. Antiovulatory Activity
• HCG-induced Ovulation in Rats.
Principle :
Immature female albino rats do not ovulate spontaneously and
do not show cyclic changes of the vaginal epithelium. Priming
with human chorionic gonadotropin (HCG) induces follicular
maturation, followed by spontaneous ovulation 2 days later.
Injection of anti-ovulatory drugs, prior to the induction
procedure will prevent ovulation. This principle is used for the
screening of anti-ovulatory agents.

12. Procedure :
immature female albino rats(24-26 days)
Treated with various test drugs in a different dose levels
After the administration of test drug
HCG is given exogenously for ovulation
After 2 days
Animals are sacrificed
Ovaries are dissected out, preserved In 10% buffered solution
and subjected to histopathological evaluation
Result are compared with control group

13. Carbonic Anhydrase activity in rabbits
endometrium
• Principle:-This is linear dose response relation ship b/w
dose of progestogens and carbonic anhydrase activity in
rabbit endometrium.
• Procedure:-
 Immature female albino rat are used in this study.
• The animal are primed with estradiol and followed by the
administration of test and std drug.
• After the drug treatment animal are sacrificed and uteri are
removed.
• The endometrium extract of the uterus is evaluated for the
carbonic anhydrase activity calorimetrically.

14. Prevention of Abortion in Oxytocin
Treated Pregnant Rabbits
• Principle:-IV administration of oxytocin to the pregnant
rabbit on 30 day of pregnancy causes abortion .prior
administration of progestational compound s prevents the
abortion.
• Procedure :-
• Ten units of oxytocin are administered iv to pregnant rabbits
on day 30 of pregnancy .
• 24 h before oxytocin ,Test and std drug in oil are injected
• control animal are not receiving drug abort within 2-30 min
after oxytocin.
• The drugs,which are having progestational activity,prevent
abprtion.

15. In Vitro Methods
• Estrogenic Activity
1. Estrogen receptor binding assay
• Anti-Progestational Activity
1. Anti-progestational Activity In Immature Rabbits
• Anti-implantation Activity

16. Estrogenic Activity
• Estrogen receptor binding assay
Principle :
Estrogen receptor binding assay uses the principle of
competitive binding of labeled and unlabeled
estrogen on the estrogenic receptors. Estrogenic
compounds displace the labeled estrogen in a
concentration dependent manner from th eestrogen
receptor.

17. Procedure:
Uterus removed from Female albino mice
(18 days old)
Homogenized at 0 C OF Tris sucrose buffer in a
conical homogenizer
Human endometrium from menopausal women
is frozen within two hour of hysterectomy
Stored in liquid nitrogen until use

18. Cont.....
Frozen endometrium homogenized in Tris- sucrose buffer
Homogenates are centrifuged for 1 h
Determination of specific binding in mouse uterus cytosol as a
function of steroid conc. Incubation time and temp
Triplicate aliquots of 125 ml of cytosol are incubated with 5
or 25 nm labeled steroid either for 2 or 24 h at 0 C for 2 or
5 hours at 25 C

19. Anti-Progestational activity in Rabbits
• Principle:-the anti progestational comp inhibit
some/all the physiological effect of
progesterone.
• The principle is used to screening the anti-
progestational activity

20. Mc Ginty TEST
• Immature rabbits(700-950g) are taken direct injected progesterone
into a uterine segment.
• Estardiol at a dose of 1 micro gram per kg per rabbit is injected by Sc
route to the rabbit of positive control and test group.
• The rabbit of negative control group received only the vehicle (0.5 %
CMC ) by subcutaneous route for 6 days.
• On the 7th day, the rabbit is anesthetized by intramuscular injection of
ketamine hydrochloride (Dose 35 mg/kg).
• The abdomen is open and the uterus is exposed by laparotomy.
• The upper middle segment of each horn is ligated without
disturbance of blood circulation.
• In positive control group, 0.1 ml of progesterone was injected alone
in the right uterine horn (Conc. 0.1 mg/ml).

21. Cont......
• In the opposite horn,only 0.1mlof the vehicle is
injected
• In the test group a solution of progesterone and
the test drug in 0.5%C.M.C is injected into the left
lumen of segment through the lower
ligature,which is drawn tight after the injection .
• Progesterone is injected alone in the right uterine
horn.
• In the negative control group,progesterone alone
is injected in the right uterine horn

22. Cont...
• In the opposite horn only vehicle is injected.
• After the injection,the lower ligature can be
tightened.
• 3 days later,the animal were sacrificed.
• The uteri was excised,weighed,fixed in buffered
formaline.
• The section of the horn are evaluated
histologically according to Mc phail score
•

23. Thank you