<prompt> Which of the following drug is not used in the treatment of preterm labour?RitodrineMgSO4SalbutamolChlorpromazine  <response>: Ritodrine, salbutamol and magnesium sulphate are tocolytic drugs used to terminate preterm labour and delivery. Other tocolytic drugs are isoxsuprine, indomethacin, calcium channel blockers, glyceryl trinitrate, atosiban and glyceryl trinitrate. Reference: Textbook of Obstetrics By D C Dutta, 6e page 508. 