28-year-old pregnant lady comes to the ER with headache, blurring of vision and vomiting. On examination, her BP is 195/150 mm Hg, ankle edema present, urinary proteinuria present. On inquiry, she is primi and it is 23 weeks of gestation. All on a sudden, she develops convulsion. Intravenous magnesium sulphate is introduced immediately and she recovers smoothly. During discharge, which of the following medication will be justified?