Obstetric Pharmacology

Magnesium Sulfate 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 Indications Anticonvulsant effects in: Pre-eclampsia

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

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

Magnesium Sulfate Antidote to toxic effects Calcium

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

Pitocin Action Synthetic oxytocin Stimulates uterine smooth muscle contraction

Pitocin Indication Control of postpartum hemorrhage

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

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

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