Neuraxial blockade such as spinal anaesthesia can cause severe hypotension due to pharmacological sympathectomy resulting in potential deleterious consequences for the patient, Prevention of this spinal anaesthesia induced hypotension is of utmost importance, Techniques currently in use for preventing hypotension include intravenous fluid prehydration, sympathomimetic drugs, and physical methods such as positioning and leg compression.

Midodrine is an orally active α-adrenergic agonist ,Used in clinical management of patients with orthostatic hypotension or hypotension secondary to other clinical conditions or drug therapies. Midodrine is almost completely absorbed after oral administration and undergoes enzymatic hydrolysis to form its pharmacologically active metabolite, de-glymidodrine , causes venous and arterial vasoconstriction through stimulation of α1- receptors located in the vasculature, However ,Midodrine may cause several side effects as chills ,numbness , tingling ,paresthesia ,polyuria ,dysuria and headache.

On the other hand, Norepinephrine is a vasoconstrictor that predominantly stimulates α1 receptors to cause peripheral vasoconstriction and increase blood pressure. It also has some β1 receptor agonist activity that results in a positive inotropic effect on the heart at higher doses. Norepinephrine also may cause side effects as headache, blurred vision, chest pain ,nervousness, bradycardia or tachycardia.

Inclusion Criteria:

1. The study will include 90 adult female patients, 45 in each group (between 18-35 years old).
2. patients of ASA physical status class I and class II.
3. patients scheduled for elective cesarean section under spinal anesthesia.

Exclusion Criteria:

1. Patient refusal.
2. Contraindication to spinal anesthesia .
3. Patients known allergic to Midodrine or Norepinephrine.
4. Patients with preexisting cardiovascular or cerebrovascular disease.
5. Patients with diabetes mellitus.
6. Patients with psychiatric disease or on psychiatric treatment.