Table 1.

Doses of most commonly used agents used for treatment of a BP of ≥160/110 mmHg hypertension (reproduced with permission from Magee et al. SOGC 2008) [5]

Agent	Dosage	Comments
Labetalol	Start with 20 mg i.v.; repeat 20–80 mg i.v. every 30 min	Best avoided in women with asthma.
	Alternative: i.v. infusion of 1–2 mg min–1 to a maximum of 300 mg (then switch to oral)	Parenteral labetalol may cause neonatal bradycardia but this is not a major problem in clinical practice
Nifedipine	5–10 mg capsule to be bitten and swallowed, or just swallowed, every 30 min	There are three types of nifedipine preparations [i.e. capsules, intermediate-release tablets (PA), and slow-release tablets (SL)] with which all staff must be familiar.
	10 mg PA tablet every 45 min to a maximum of 80 mg day–1	Nifedipine capsules cause a reflex increase in sympathetic tone which is best avoided in women for whom increased myocardial oxygen demands could be dangerous (e.g. coronary artery disease), or in the setting of fixed valvular obstruction.
Hydralazine	Start with 2–5 mg i.v.; repeat every 30 min in doses up to 10 mg, or 0.5–10 mg h–1 i.v., to a maximum of 20 mg i.v. (or 30 mg i,m,)	May increase the risk of maternal hypotension.
		Hydralazine causes a reflex increase in sympathetic tone which is best avoided in women for whom increased myocardial oxygen demands could be dangerous (e.g. coronary artery disease), or in the setting of fixed valvular obstruction.