Hydralazine

• Acute severe HTN (≥160/110) in pregnancy
• Hypertensive crisis in pre-eclampsia

Direct relaxation of arteriolar smooth muscle → ↓ SVR → ↓ BP. Triggers reflex tachycardia and Na/H₂O retention.

• S — SLE-like syndrome (long-term)
• L — Lupus ANA positive
• E — Edema / reflex tachycardia
• T — Trigger headache & flushing

IV bolus

5 mg IV slow, repeat after 20 min (max 20 mg)

IV infusion

2–18 mg/h titrated to BP

Oral

25–50 mg QDS (rarely used antepartum)

• AbsoluteIdiopathic SLE
• AbsoluteSevere tachycardia, high-output HF
• CautionPre-load with 250–500 mL crystalloid to prevent fetal distress

• Headache, flushing
• Reflex tachycardia, palpitations
• Maternal hypotension → fetal bradycardia
• Drug-induced lupus (chronic)

• • Not teratogenic.
• • Sudden BP drop can cause non-reassuring CTG — give fluids first.
• • Safe in breastfeeding.

• MgSO₄

  Caution

  Additive hypotension

• Diazoxide

  Avoid

  Profound hypotension — avoid

• NSAIDs

  Caution

  ↓ antihypertensive effect

• 💡 Always give a fluid bolus first — fetal compromise is usually iatrogenic.
• 💡 Reassess BP every 5 minutes; do not redose before 20 min.