Nifedipine (Adalat®) 20 mg sublingual crushed, repeated after 30 minutes if contractions do not decrease in intensity. Maintenance of 120-160 mgs of slow-release nifedipine (Nifedicor®) daily for 48 hours (30 mg Q 6 hrs up to a maximum of 40 mg Q 6 hrs). Once contractions cease, nifedipine will be maintained at 80-120 mg daily in divided doses up to 36 weeks of gestation on an outside basis.