Obstetric Pharmacology

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Obstetric Pharmacology
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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

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Magnesium Sulfate

• Indications
• Anticonvulsant effects in
• Pre-eclampsia
• Eclampsia

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Magnesium Sulfate

• Contraindications
• Renal disease
• Cardiac failure
• AV conduction defects
• Myasthenia gravis

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Magnesium Sulfate

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

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Magnesium Sulfate

• Antidote to toxic effects
• Calcium

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Magnesium Sulfate

• Dose
• Initial 4 to 8 gm IV over 20 minutes
• Maintenance 1 to 2 gm/hr

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Pitocin

• Action
• Synthetic oxytocin
• Stimulates uterine smooth muscle contraction

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Pitocin

• Indication
• Control of postpartum hemorrhage

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Pitocin

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

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Pitocin

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

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Pitocin

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