The purpose of this study is to assess and contrast the effectiveness of intravenous ondansetron and intravenous hydrocortisone in avoiding spinal anesthesia-induced hypotension.

According to the medication investigated in this study, patients will be divided into three equal groups (40 each). Patients will receive one of the following 15 minutes before spinal anesthesia:

1. Hydrocortisone 100 mg (H group)
2. Ondansetron 8 mg (O group)
3. An identical volume of sterile distilled water (Control group) (C group).

Spinal anesthesia will be performed under complete aseptic conditions with the patient seated, a 25-gauge Quincke spinal needle is used to administer 3.5 ml of a 0.5% hyperbaric bupivacaine together with 25 micrograms of fentanyl at the L3-L4 or L4-L5 level.

Patients will lie supine with slight head elevation after the intrathecal injection is finished. Intravenous Infusion of 500 ml normal saline over the initial post spinal 30 minutes. Sensory level and motor block will be verified. Heart rate (HR), systolic (SBP), diastolic (DBP) and mean blood pressure (MBP) will be measured every 5 min for 30 min during which the patient remains in the supine position with no application of torniquet.

If the MAP drops by 20% below baseline or the systolic blood pressure falls below 90 mmHg, hypotension is recorded and will be treated with intravenous incremental doses of 5 mg ephedrine.

If the heart rate drops below 50 beats per minute, bradycardia is recorded, and atropine 0.5 mg will be administered intravenously. If ephedrine or atropine were used, only data from before their administration would be analyzed. The doses of ephedrine and atropine needed will be recorded.

Nausea, vomiting and shivering will be recorded when occur till the end of operation.

Inclusion Criteria:

1. ASA I and II (physical status according to American Society of Anesthesiologists).
2. Patients aged 21 years or more.
3. Either sex.
4. Abdominal and lower limb operations.

Exclusion Criteria:

1. Patient refusal.
2. hemodynamic instability
3. Hematological diseases, bleeding or coagulation abnormality.
4. Local skin infection and sepsis at site of spinal anesthesia
5. neuromuscular diseases (as myopathies, myasthenia gravies…)
6. Preexisting neurological deficit or psychiatric diseases.
7. Known intolerance to the study drugs.
8. patients already receiving any of the study drugs.
9. diabetic patient.