As modified-release tab: 8 mg bid. IV Severe bronchospasm As 50 mcg/mL soln: 250 mcg (4 mcg/kg) injected slowly. May be repeated if necessary. As 10 mcg/mL soln: Usual rate of 3-20 mcg/min (0.3-2 mL/min). Higher doses may be used in resp failure. Uncomplicated premature labour at 22-37 wk of gestation Initial: 10 mcg/min, increasing gradually at 10-min intervals until there is response, then increase rate slowly until contractions cease. Maintain rate for 1 hr after contractions have stopped, then gradually reduce rate by 50% at intervals of 6 hr. Usual: 10-45 mcg/min. Max duration: 48 hr.IM/SC Severe bronchospasm 500 mcg (8 mcg/kg) and repeated 4 hrly as required. Inhalation Acute bronchospasm As metered-dose aerosol or dry powd inhaler: 1 or 2 inhalations up to 4 times/day. Max: 800 mcg/day. Prophylaxis of exercise-induced bronchospasm As metered-dose aerosol or dry powd inhaler: 2 inhalations 10-15 min prior to exercise. Severe bronchospasm Via nebuliser: 2.5-5 mg, up to 4 times/day, or continuously at a rate of 1-2 mg/hr. Acute severe asthma As metered-dose inhaler via spacer device: Initial: 4 inhalations, then a further 2 inhalations every 2 min according to response. Max: 10 inhalations.