The slide presents the conditions of pregnant and non-pregnant uterus contraction and focuses on the pharmacology of uterine stimulants and relaxants of pregnant women.

1. Assistant Professor
Lohapur, Birbhum, WB.

2. Non- pregnant Human:
 Contracts spontaneously but weakly during 1st part of the cycle.
 More strongly during luteal phase and menstruation.
Pregnant Human:
 Uterine movements depressed in early pregnancy.
 Towards end of gestation, contractions increase in force and
frequency.
 Fully co-ordinated during parturition.

3.  Introduction: A nonapeptide hormone synthesized in the
hypothalamus.
 Storage: Neurohypophysis (posterior pituitary)
 Actions:
1. Uterus: Contraction of the pregnant uterus.
2. Breast: Contraction of myoepithelial cells, causing milk ejection.
3. Kidney: ADH- like action, decreases urine output.
4. Blood vessels: Vasodilatation.

4.  Oxytocin binds to specific G- protein coupled receptors on
myometrium.
 This leads to:
1. Generation of Inositol trisphosphate (IP3)
2. Release of Ca2+ from intracellular stores
3. Increased production of Prostaglandins by endometrium
 Contraction of the pregnant uterus

5. Induction of labour
 Reasons:
a. Toxaemia of pregnancy
b. Erythroblastosis faetalis
c. Ruptured membrane
d. Diabetic mother
e. Placental insufficiency
To prevent postpartum haemorrhage (PPH)
To augment uterine contractions
Breast engorgement

6. 1. Natural Hormone:
Oxytocin, Desaminooxytocin
2. Ergot Alkaloids:
Ergometrine (Ergonovine), Methylergometrine
3. Prostaglandins:
PGE2, PGF2α, 15- Methyl PGF2α, Misoprostol
4. Miscellaneous:
Ethacridine, Quinine

7. 1. Adrenergic Agonists:
Ritodrine, Salbutamol, Terbutaline, Isoxsuprine
2. Calcium Channel Blockers:
Nifedipine
3. Oxytocin Antagonist:
Atosiban
4. Magnesium Sulphate
5. Miscellaneous:
Ethyl alcohol, Nitrates, Progesterone, Indomethacin, General Anaesthetics

8. 

9.  Pharmacologic Action
1. Uterus: Stimulate contractions involving both upper and
lower segments.
2. CVS: Weak vasoconstriction.
3. GI tract: Peristalsis increased in high doses.
 Therapeutic Use
1. Prevention and treatment of postpartum haemorrhage.
2. Prevention of uterine atony.
3. To hasten involution of uterus.

10.  PGE2, PGF2α and 15- Methyl PGF2α are
potent uterine stimulants
 They cause ripening and dilatation of cervix

11. 

12.  Ritodrine, the preferred β2 selective agonist has
prominent uterine relaxant action and is approved
to suppress premature labor and to delay delivery.
 Salbutamol and Terbutaline can be used
alternatively.
 Isoxsuprine oral / i.m. has been used to stop
threatenend abortion, but its efficacy is uncertain.

13.  Mechanism of Action
 It acts by inhibiting the influx of Ca2+ ions and reducing
the tone of myometrium to oppose contractions.
 Other info
 It can postpone labour if used early enough.
 It is used orally.
 Adverse Effect
 Tachycardia and hypotension.

14.  It is a peptide analogue of oxytocin which competitively
blocks the oxytocin receptors of the uterus and induces
uterine relaxation.
 It is given by i.v. infusion.
 It suppresses premature uterine contractions and
postpones preterm delivery.
 Its cardiovascular and metabolic complications are less
than β2 agonists.

15.  It acts as a tocolytic by competing with Ca2+ ions for entry
into myometrium through both voltage sensitive as well as
ligand gated Ca2+ channels.
 It is a first line drug for prevention and treatment of
seizures in preeclampsia and eclampsia.
 It is given by i.v. infusion.
 Currently, it is only used when β2 agonists are
contraindicated.
 Its use to delay premature labour is not safe as it may
increase perinatal mortality.

16. 1. To delay preterm labour
2. Threatened abortion
3. Dysmenorrhoea