Obstetric Pharmacology

Magnesium Sulfate n Actions Not clearly understood Seems to decrease release of acetylcholine at neuromuscular junction Depresses central nervous system Causes mild vasodilation –Decreases blood pressure –Improves placental blood flow

Magnesium Sulfate n Indications Anticonvulsant effects in: –Pre-eclampsia –Eclampsia

Magnesium Sulfate n Contraindications Renal disease Cardiac failure AV conduction defects Myasthenia gravis

Magnesium Sulfate n Adverse effects Muscle weakness Respiratory depression Hypotension Slowed cardiac conduction/AV blocks

Magnesium Sulfate n Antidote to toxic effects Calcium

Magnesium Sulfate n Dose Initial: 4 to 8 gm IV over 20 minutes Maintenance: 1 to 2 gm/hr

Pitocin n Action Synthetic oxytocin Stimulates uterine smooth muscle contraction

Pitocin n Indication Control of postpartum hemorrhage

Pitocin n Contraindication Do not administer until after baby, placenta fully delivered May cause trapping of placenta or second twin in uterus

Pitocin n Adverse effects Nausea, vomiting Cardiac arrhythmias Fluid retention with water intoxication Transient vasodilation, reflex tachycardia

Pitocin n Dose 10 to 40 units in 1 L of crystalloid Infuse to: –Sustain uterine contraction –Control hemorrhage