A Randomized, Controlled, Double blind study aiming to evaluate the analgesic potentials and side effect profile of different dose levels of Dexmedetomidine added to subarachnoid bupivacaine in full-term pregnant women undergoing elective cesarean section using spinal anesthesia. The investigators ultimate goal is to find out the least effective dose which will be associated with minimal or no side effects. The primary outcome will be the time to two sensory block segment regression.

Alpha 2-agonists are non-opioid adjuvants with a significant role in extending the analgesic duration of subarachnoid block. When clonidine or Dexmedetomidine was added to intrathecal local anesthetics, the regression of sensory and motor blocks increased dose-dependently. Further, a recent meta-analysis including seven randomized controlled studies reported an increase in the duration of analgesia and reduced morphine requirement after the concomitant subarachnoid administration of clonidine.

Animal studies demonstrated that Dexmedetomidine added to bupivacaine significantly enhanced the duration of sensory and motor blockade of sciatic nerve block. Histo-pathological examination proved that all of the nerves analyzed had normal axons and myelin at 24 h and 14 days after the peri-neural administration of Dexmedetomidine. Several clinical studies confirmed the analgesic potentials and safe neurological outcome of neuraxially administered Dexmedetomidine in the non-obstetric settings while intrathecal clonidine proved to be a useful analgesic adjunct for spinal anesthesia in patients undergoing cesarean section. But to the best of the investigator knowledge the effects of intrathecal Dexmedetomidine on the perioperative clinical profile of bupivacaine-induced spinal anesthesia were not studied before in the obstetric patient population.

Inclusion Criteria:

• Full-term pregnant women.
• Elective cesarean section using spinal anesthesia.
• Singleton gestation.
• American Society of Anesthesiologists (ASA) physical status classes I and II.

Exclusion Criteria:

• Preterm pregnancy (<37 wks gestation).
• Multiple gestation.
• Cardiovascular disease (e.g., preeclampsia, hypertension) and the use of antihypertensive medication.
• Conditions that preclude spinal anesthesia.
• Failed spinal block and conversion to general anesthesia.
• A history of established chronic pain.
• Drug addiction.
• A psychiatric disorder.
• Inability to communicate effectively.
• Asthma and allergy to non-steroidal anti-inflammatory drugs.