Spinal anesthesia is an established technique used in obstetric surgeries, It provides adequate analgesia both intra and post-operative and also avoids complications associated with general anesthesia for mother and fetus. The quality of spinal anesthesia has been reported to be improved by using additives Dexmedetomidine is a highly selective α2-adrenoreceptor agonist that has been introduced to anesthesia. It produces dose-dependent sedation, anxiolysis, and analgesia without respiratory depression. Neostigmine is an anticholinesterase agent, which inhibits the hydrolysis of acetylcholine by competing with acetylcholine for attachment to acetyl cholinesterase; administration of Neostigmine through intrathecal route apparently activates the descending pain inhibitory system that relies on spinal cholinergic interneuron. Study conducted to evaluate whether neostigmine given by intrathecal route with 0.5% hyperbaric bupivacaine for spinal anesthesia can provide prolongation of sensory blockade duration as effective as dexmedetomidine given by the same route and in compination with same drug with lower cost, more stable hemodynamics and comparable side effects. After obtaining Institutional Ethics Committee approval and written informed consent,54 patients American Society of Anesthesiologist (ASA) physical status I and II were enrolled into the study and were randomlyassigned into 3 groups. Group 1were received 10 mg (2ml) hyperbaric bupivacaine and 0.1 ml (10 μg) DXM and 0.1 ml normal saline, Group 2 were received 10 mg (2ml) hyperbaric bupivacaine and 0.1 ml (50 μg) neostigmine and 0.1 ml normal saline and Group 3were received 10 mg (2ml) hyperbaric bupivacaine and 0.2 ml normal saline as control.

The investigators measured the time to reach T4 dermatome sensory block, peak sensory level, Time to reach Bromage 3 motor block, the regression time for sensory and motor block, also the investigators measured hemodynamic, sedation score, visual analogue score, any complications occurred and Apgar score for fetus during blockade and the investigators assessed the duration of pain relief .

Inclusion Criteria:

1. ASA physical status I and II patients
2. Age: 18 - 40 years
3. Height 150 - 170 cm
4. Weight 70 - 110 kg.

Exclusion Criteria:

1. Patient refusal
2. Cardiac diseases as ( ischemic heart disease, severe valvular stenosis, pulmonary hypertension, uncontrolled arrhythmias )
3. Severe labile hypertension BP more than 160 / 100 )
4. Raised intracranial pressure or pre-existing neurological disorders, such as multiple sclerosis.
5. Patients with coagulopathy: platelets < 100,000 INR ≥ 1.3 or therapeutic use of anti-coagulants.
6. Inability to communicate and understand the aim of the project.
7. Patients with history of allergic reaction to LA, DXM or Neostigmine.
8. Skin infection at injection site or systemic bacteremia.
9. Failure of the block and need for general anesthesia.