Usage and Dosage: 1. Common dosage for adults: (1) For blood pressure increase: intramuscular injection, at a dose of 5-10 mg for mild hypotension (10-15 mg in general), 10 mg when the upper limit of spinal block is low and 15-20 mg when it is high; slow intravenous injection at a dose of 3-5 mg; (2) Anti-arrhythmia: slow intravenous injection at a dose of 10mg. 2. Maximal dosage: intramuscular injection at a dose of no more than 20 mg per time and no more than 60 mg per day; intravenous injection at a dose of no more than 10 mg per time.