Table 2.
Commonly used agents for severe and non-severe pregnancy hypertension (modified from PvD CHR).
| Indication/Agent | Dosage | Onset | Peak | Duration | Comments |
|---|---|---|---|---|---|
| Severe hypertension | |||||
| Hydralazine | Start with 5 mg iv; repeat 5–10 mg iv every 3 min, or 0.5–10 mg/h iv, to a maximum of 20 mg iv (or 30 mg im) | 5 min | 30 min | 2–4 h | May increase the risk of maternal hypotension. Appears less effective than nifedipine but more effective than labetalol. |
| Labetalol iv | Start with 20 mg iv; repeat 20–80 mg iv every 30 min, or 1–2 mg/min (then switch to oral (max 300 mg)) | 5 min | 30 min | 4 h | Best avoided in women with asthma or heart failure. Neonatology should be informed if the woman is in labour, as parenteral labetalol may cause neonatal bradycardia. |
| Labetalol po | 200 mg loading dose; repeat further 200 mg doses every 45 min (then switch to regular oral (max 1200 mg/d)) | 20 min–2 h | 1–4 h | 8–12 h (dose-dependent) | |
| Nicardipine iv | Initial infusion rate 2.5–5 mg/h, increasing by 2.5 mg/h every 5 min (max 15mg/h) | 5 min | 20 min | 4–6 h | Currently not recommended as a first-line agent by any national or international guideline committee |
| Nifedipine capsule | 5–10 mg capsule to be swallowed or bitten then swallowed every 30 min | 5–10 min | 30 min | ≈6 h | Be aware of the distinction between short-acting nifedipine capsules, the intermediate-acting tablets and the slow-release tablets. Avoid nifedipine capsules in women with known coronary artery disease, severe aortic stenosis and pre-existing diabetes of ≥15 y duration due to risks of acute coronary syndromes. |
| Nifedipine intermediate-acting/PA | 10 mg tablet; repeat 10 mg doses every 45 min (then switch to regular oral medication) (max 120 mg/d) | 30 min | 4 h | 12 h | |
| Non-severe hypertension | |||||
| Methyldopa | 250–500 mg po bid-qid (max 2 g/d) | 40 min | 3–6 h | 12–24 h | There is no evidence to support a loading dose of methyldopa. CHIPS data suggest that methyldopa is preferable to labetalol. There are reassuring neurodevelopmental data for methyldopa. |
| Labetalol | 100–400 mg po bid-tid (max 1200 mg/d) | 20 min–2 h | 1–4h | 8–12 h (dose-dependent) | Best avoided in women with asthma or heart failure. Some experts recommend a starting dose of 200 mg po bid. |
| Nifedipine intermediate-acting/PA | 10-40 mg tablet po bid-tid (max 120 mg/d) | 30 min | 4 h | 12 h | Be aware of the distinction between short-acting nifedipine capsules, the intermediate-acting tablets and the slow-release tablets |
| Nifedipine XL preparation | 20–60 mg po OD (max 120 mg/d)) | 60 min | 6 h | 24 h | |