Patients were given either MgSO4 50 mg kg ( -1 ) in 10 mL within 10 min , followed by an infusion of MgSO4 10 mg kg ( -1 ) hr ( -1 ) IV in 4mL ( MG group ) for 12 hrs or normal saline in same volume and rate for 12 hrs as used in MG group ( NS group ) .