 METHODS: Patients are randomised to receive nifedipine 10 mg tablet, orally, up to five doses and intravenous placebo saline injection or intravenous labetalol injection in an escalating dose regimen of 20, 40, 80, 80 and 80 mg and a placebo tablet every 15 minutes until the target blood pressure of 14090mmHg is achieved. Crossover treatment is given if the initial treatment regimen is unsuccessful 