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Oxytocics & Tocolytics

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Oxytocics & Tocolytics

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A brief introduction regarding oxytocics & tocolytics which are the indispensable drugs in obstetrics. It consists of illustrative images, classification of drugs with their dosage, uses & side-effects along with contraindications

A brief introduction regarding oxytocics & tocolytics which are the indispensable drugs in obstetrics. It consists of illustrative images, classification of drugs with their dosage, uses & side-effects along with contraindications

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Oxytocics & Tocolytics

  1. 1. OXYTOCICS & TOCOLYTICS By: Ankita Priydarshini
  2. 2. OXYTOCICS Oxytocics also called Uterotonics have the power to stimulate uterine contractions.
  3. 3. Mechanism of action :- On uterine oxytocin receptor (T3) Voltage mediated Ca2+ channels Physiological uterine contractions 1. Oxytocin
  4. 4. Onset :- Half life of 3-4 minutes. Duration of action :- approx. 20 mins. Dosage :- Start with low dose (1-2mU/min.) & to escalate by 1-2 MIU/min. at every 20 mins. intervals upto 8mU/min. ROA :- a). Controlled i.v. infusion b). Bolus IV or IM - 5-10 units after birth of baby as an alternative to ergometrine. c). IM - (synometrine= syntocinon 5U + Ergometrine 0.5mg) d). Buccal tablets (50IU) or nasal spray (40units/ml)
  5. 5. Clinical uses :- a). In the induction of labour b). to augment uterine contraction during labour c). to stop PPH Hazards :- Uterine hyperstimulation, Anti-diuretic effect, Uterine rupture, anginal pain, hypotension Contraindications :- Pregnancy Labour Any time Grand Multipara All contraindications in pregnancy Hypovolemic state Contracted pelvis Obstructed labour Cardiac disease H/O C-section or hysterotomy Inco-ordinated uterine contraction Malpresentation Fetal distress
  6. 6. Mechanism of action :- a). directly on myometrium b). tetanic uterine contractions (US/LS) Onset :- IV - 1 & half min. IM - 7 min. Oral - 10 mins. DOA :- 3 hours Dosage :- 0.2mg slow i.v. every 30 mins. (max. 5 doses can be given within 24 hours) ROA :- IV, IM, Oral Clinical Uses :- a). To stop haemorrhage after delivery, abortion or expulsion of H. mole b). Prophylactic use in late 2nd or 3rd stage, to hasten separation of placenta & to minimise blood loss. 2. Methergin
  7. 7. Hazards :- Nausea & vomiting Rise in B.P. Rarely gangrene of the toe Intereference with lactation Contraindications :- Prophylactic Therapeutic Suspected pleural pregnancy Cardiac disease Organic cardiac disease Severe hypertensive disorders Severe pre-eclampsia & eclampsia Rh-negative mother
  8. 8. 15-methyl PGF 2 alpha ; 1 ml ampoule - 250µg of Prostadin Mechanism of action :- Change in myometrial permeability &/or alteration in membrane bound Ca2+ Sensitises myometrium to oxytocin Dosage :- T2 abortion : 1ml ampoule i.m. every 3 hrs till patient aborts (max.10 doses) Prophylaxis of atonic PPH : 0.5-1ml IM ℞ of atonic PPH : 1 ml IM, can be repeated after 30 mins Clinical Uses :- a). T2 abortion b). Atonic PPH Adverse Effects :- Hyperstimulation, Rupture uterus Contraindications :- Uterine scar 3. Carboprost
  9. 9. Prostaglandin derivative - used for cervical ripening Mechanism of action :- Change in myometrial permeability &/or alteration in membrane bound Ca2+ Sensitises myometrium to oxytocin Onset :- Half life- 1-2 mins Dosage :- Refractory cases of PPH - 600µg - 1000µg (PR) For induction - 25µg every 4th hourly (max. 8 doses) Abortion : T1: Mifepristone + Misoprostol Protocol: Day1 - Mifepristone 600mg orally Day 3 - Misoprostol 400µg orally 4. Misoprostol
  10. 10. Clinical Uses :- a). Induction of labour b). Induction of abortion (MTP & missed abortion) c). Termination of molar pregnancy d). Management of atonic PPH e). Medical management of tubal ectopic pregnancy Hazards :- Tachysystole of uterus Meconium passage Uterine rupture As an abortifacient - extensive cervical lacerations may occur Contraindications :- Hypersensitivity to the compound Uterine scar - known to cause rupture Active cardiac, pulmonary, renal or hepatic disease
  11. 11. Preterm labour & delivery can be delayed by drugs in order to improve the perinatal outcome & thus reduce perinatal morbidity & mortality significantly. TOCOLYTICS
  12. 12. Mechanism of action of Tocolytic drugs
  13. 13. E.g. - Nifedipine, Nicadipine, Verapamil Mechanism of action :- It blocks the entry of calcium inside the cell Doses :- Oral 10-20mg every 3-6 hours Side effects & precautions :- Maternal : Hypotension Headache Flushing & nausea Combined therapy with Beta mimetic or MgSO4 should be avoided 1. Calcium Channel Blocker
  14. 14. Mechanism of action :- Acts by competitive inhibition of Ca2+ ion either at the motor end place at the cell membrane reducing calcium influx. es acetylcholine release & its sensitivity at motor end plate. Direct depressant action on uterine muscle. Doses :- Loading dose 4-6g IV (10-20% solution) over 20-30 mins followed by an infusion of 1-2g/hr to continue tocolysis for 12 hrs after the contractions have stopped. Tocolytic effects is poor. Side effects & precautions :- It is relatively safe. Common maternal side effects are flushing, perspiration, headache, muscle weakness, rarely pulmonary oedema. Neonatal side effects are lethargy, hypotonia, rarely respiratory depression. Contraindications : Pts with myasthenia gravis & impaired renal function. 2. Magnesium Sulphate
  15. 15. Mechanism of action :- es synthesis of PGs thereby es intracellular free Ca++, activation of MLCK & uterine contractions. Doses :- Loading dose 50mg PO or PR followed by 25mg every 6 hrs for 48 hrs. Side effects & precautions :- Maternal : Heart burn, asthma, GI bleeding, thrombocytopenia, renal injury. Contraindications : Hepatic disease, active peptic ulcer, coagulation disorders. Fetal & neonatal side effects : Constriction of dusts arteriosus, oligohydramnios, Neonatal pulmonary hypertension, IUGR 3. Indomethacin Cyclo-oxygenase inhibitor) [ Suldinac another NSAID is also used as it has less placental transfer]
  16. 16. Mechanism of action :- Activation of intracellular enzymes (adenylate cyclase, cAMP, Protein kinase, es intracellular free Ca++ ( Ca++) & inhibits activation of MLCK ( ) Reduced interaction of actin & myosin smooth muscle relaxation. Doses :- Ritodrine is given IV infusion, 50µg/min & is increased by 50µg every 10 mins until contraction cease. Infusion is continued for about 12hrs after contractions cease. Terbutaline has longer 1/2 life & has fewer side effects. Subcutaneous injection of 0.25mg every 3-4 hrs is given. Side effects :- Maternal : Headache, palpitation, tachycardia, pulmonary oedema, hypotension, cardiac failure, ARDS, lactic acidaemia & even death. Fetal: Tachycardia, heart failure, IUFD. Neonatal : Hypoglycaemia & intraventricular haemorrhage. 4. Betamimetics E.g. - Terbutaline, Ritodrine, Isoxsuprine (Effective for 48 hrs to allow time for steroids & antibiotics to work
  17. 17. Mechanism of action :- blocks myometrial oxytocin receptors. It inhibits intracellular Ca++ release, release of PGs & thereby inhibits myometrial contractions. Doses :- IV infusion 300µg/min. Initial bolus may be needed. Side effects :- Nausea, vomiting, chest pain (rarely). 5. Oxytocin Antagonists E.g. - Atosiban
  18. 18. Mechanism of action :- Smooth muscle relaxant Doses :- Patches Side effects :- May cause cervical ripening, Headache 6. Nitric Oxide (NO) Donors E.g. - Glyceryl trinitrate (GTN)

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