Uterine Stimulants/Uterine Motility Drugs(Oxytocics)
Uterine motility drugs stimulate uterine contractions to assist labor (oxytocics) or induce abortion (abortifacients).
Oxytocics
Oxytocics stimulate contraction of the uterus, much like the action of the hypothalamic hormone oxytocin, which is stored in the posterior pituitary. These drugs include
- Ergonovine (Ergotrate)
- Methylergonovine (Methergine)
- Oxytocin (Pitocin, Syntocinon).
Oxytocin
Legal class; class B controlled drugs
Medical class; oxytocic drugs
Form; sterile solution for injection
Strength; 10 IV per ampule.
Indications of Oxytocin
- Induction of labor
- Cases of inter-uterine fetal death.
- Hypotonic uterine contractions
- Mothers with hypertension
- After delivery to control bleeding
- Pre-eclampsia and eclampsia
- Congestive cardiac failure
- Post term
- Prevent PPH
- Incomplete or missed abortion.
- Active management of third stage of labor.
Contraindications of Oxytocin
- Hypertonic uterine
- Fetal and maternal distress
- Multiple pregnancy
- Trial of labor
- Mal presentation like breech, brow
- Cephalo pelvic disproportion
- Low blood pressure
Dose
- Induction/argumentation of labour; 5 I.U into 500mls of solution for infusion, initially, 5 drops per min.
- Preventing of PPH after delivery of the placenta; Slow I.V, 5 I.U, increase rate during 3rd stage.
Route
- Intramuscular
- Intravenously when mixed with normal saline or dextrose
Side Effects
- Dizziness
- Nausea and vomiting
- Rashes
- Fetal brandy cardia
- Hypotension
Adverse Effects
- Lead to ruptured uterus
- Hypotension
- Tachycardia
- Intra uterine fetal anoxia and hypoxia to the fetus leading to birth asphyxia.
Pharmacokinetics
- Absorption is immediate following IV injections
- Drug is distributed throughout the extracellular fluid. Some amount enters the fetal circulation.
- It is metabolized rapidly in kidney and liver in small amount and are excreted in urine
Abortifacients
Abortifacients are used to evacuate uterine contents via intense uterine contractions. These drugs include;
- Misoprostol
- Carboprost (Hemabate)
- Dinoprostone (Cervidil, Prepidil Gel, Prostin E2)
- Mifepristone ( Mifeprex).
Misoprostol
Legal class; class B controlled drugs
Medical class; oxytocic drugs/ cervical, rippening agent
Form; tablet
Strength; 200mcg/ 100mcg tablet
Indications
- Induction of labour
- Control post partum hemorrhage due to uterine atony
- Before cervical dilatation
- Intra-uterine fetal death
- Gastric and deudenal ulcerations
Contraindications
- Mal presentation
- Placeta previa grade 3 and 4
- Multiparous mothers
- Cephalo pelvic disproportion
- Hypersensitivity to misoprostol
Dose
- Induction of labour; 100mcg vaginally every after 12hrs
- NSAID ulcerations; 200mcg 4 times a day
Route
- Sublingually
- Rectally
- Vaginally
Side Effects
- Headache
- Dizziness
- Fever
- Shivering
- Vomiting
- Uterine rupture
- Fetal distress.
- Constipation
Pharmacokinetics.
Absorbed in the GIT and distributed widely through out the body metabolised in the liver and is excreted in urine.
DINOPROSTOL
Available preparation – 3mg tab
Available brand – Prostin
Pharmacokinetics
Following vaginal insertion, it diffused slowly into the maternal blood.
There is also some local absorption into the uterus through the cervix
It is distributed widely in the molter, metabolized in the lungs, liver, kidney, spleen and other maternal tissues and excreted in urine with small amount in faeces.
Indications
- Induction of labor
- Missed abortion
Contraindications
- Active cardiac diseases
- Multiple pregnancy
- Hypersentivity to dinoprostol
- Untreated pelvic infection
- Caesarian section
Dose : 3 mg vaginally
Side Effects
- Abdominal pain
- Nausea and vomiting
- Hypotension
- Shivering
- Back pain
- Rapid cervical dilatation
SYNTOMETRINE
Legal class; class B controlled drugs
Medical class; oxytocic drug
Form; sterile solution for injection
Strength; combination of ergometrine and Pitocin ( ergometrine 0.5 mg + Pitocin 5 IU) –It exists in an ampules of 1 mill
Dose
- I ml as single dose but can be repeated where necessary if bleeding is not controlled
Route
- Intramuscular
- Intravenous
Indications
- Give to multi gravidas after delivery
- Mothers with a history of post partum hemorrhage
- Multiple or twin delivery because of large placental site
- Mothers with heavy lochia
- Abortion when fundal height is less than 12 weeks
Contraindications
Mothers with cardiac disease, pre eclampsia, eclampsia and hypertension.
Adverse Effects
- Retained placenta
- IUFD in undiagnosed second twin
- Lead to retained 2nd twin
- Uterine rapture if given in abortion, above 20 weeks of gestation products of conception are not fully out.
- Causes hypoxia and anoxia
Side Effects
- Nausea and vomiting
- Headache
- Hypotension
- Dyspnea
- Muscle pain
ERGOMETRINE
Legal class; class B controlled drugs
Medical class; oxytocic drug
Form; tablet and sterile solution
Strength/dosage; tabs 0.25 to 0.5mg tab
Injection 200mcg/ml
0.5mg/ml
EFFECTS
It causes sudden prolonged intermittent uterine contraction
INDICATION
Contra indications
Side effects
Dangers
(Are the same as for syntometrine)