Drugs Acting on Uterus.pptx

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. DRUGS ACTING ON UTERUS Anirban Kumar Bora Assistant Professor Gitanjali College of Pharmacy Lohapur, Birbhum, WB.

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

4. OXYTOCIN: M ECHANISM OF A CTION Oxytocin binds to specific G- protein coupled receptors on myometrium. This leads to: Generation of Inositol trisphosphate (IP 3 ) Release of Ca 2+ from intracellular stores Increased production of Prostaglandins by endometrium Contraction of the pregnant uterus

5. Induction of labour Reasons: Toxaemia of pregnancy Erythroblastosis faetalis Ruptured membrane Diabetic mother Placental insufficiency To prevent postpartum haemorrhage (PPH) To augment uterine contractions Breast engorgement OXYTOCIN: USES

6. CLASSIFICATION 1. Natural Hormone: Oxytocin, Desaminooxytocin 2. Ergot Alkaloids: Ergometrine (Ergonovine), Methylergometrine 3. Prostaglandins: PGE 2 , PGF 2 α , 15- Methyl PGF 2α , Misoprostol 4. Miscellaneous: Ethacridine, Quinine  UTERINE STIMULANTS (OXYTOCICS)

7. CLASSIFICATION 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  UTERINE RELAXANTS (TOCOLYTICS)

8. UTERINE STIMULANTS (OXYTOCICS)  

9. Ergometrine, Methylergometrine Pharmacologic Action Uterus: Stimulate contractions involving both upper and lower segments. CVS: Weak vasoconstriction. 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. Prostaglandins PGE 2 , PGF 2 α and 15- Methyl PGF 2α are potent uterine stimulants They cause ripening and dilatation of cervix

11. UTERINE RELAXANTS (TOCOLYTICS)  

12. Adrenergic Agonists Ritodrine , the preferred β 2 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. Nifedipine Mechanism of Action It acts by inhibiting the influx of Ca 2+ 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. Atosiban 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 β 2 agonists.

15. Magnesium sulphate It acts as a tocolytic by competing with Ca 2+ ions for entry into myometrium through both voltage sensitive as well as ligand gated Ca 2+ 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 β 2 agonists are contraindicated. Its use to delay premature labour is not safe as it may increase perinatal mortality.

16. USES OF TOCOLYTICS To delay preterm labour Threatened abortion Dysmenorrhoea

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