This prospective parallel group double blinded randomized study will be conducted over 60 adult participants between 20 and 60 years ASA (American Association of Anesthesiologists) I and II. The participants will be randomly allocated in 2 groups. Group A will receive 900 mg of gabapentin before surgery in 2 divided doses; 300 mg 10 hours prior to surgery and 600 mg 2 hours before surgery, while group B will receive 2 placebo tablets at the same time. The participants will receive spinal anesthesia in the form of 3ml of hyperbaric bupivacaine 0.5%. Hemodynamics will be recorded every 15 minutes till the end of surgery. Sensory, and motor block progression, and regression will be recorded also.

A prospective double blinded randomized trial to study the effect of gabapentin on the duration of spinal anesthesia. The participants will be divided into 2 groups. Group A will receive 900 mg of gabapentin before surgery in 2 divided doses; 300 mg 10 hours prior to surgery and 600 mg 2 hours before surgery, while group B will receive 2 placebo tablets at the same time.

The patient will be seated and after sterilization of his back with povidone iodine, a midline intrathecal injection of the 3ml of hyperbaric bupivacaine 0.5% at L 3/4 - L4/5 will be done via a 25G needle. Neural block will be assessed by using pin prick test, motor block will be assessed by using the modified Bromage scale, results will be recorded every 3 min until the level is stable for 3 consecutive tests.

After successful intrathecal injection, the patient will be monitored continuously for block progression and complications. The patient's blood pressure will be taken every 3 minutes initially, more frequently if needed. The patient will be monitored for the following:

Ensure that the block is adequate for the surgical procedure and it does not progress too high (motor block will be assessed by modified Bromage score and the sensory level by pin prick test up to T7-T10 level)

Sensory block will be assessed by pin prick test (Hollman test) using a 3-point scale; (0) = Normal sensation, (1) = Loss of sensation of pin prick (analgesia), and (2) = Loss of sensation of touch (anesthesia).

Onset time for sensory block will be defined as the time interval between the end of local anesthetic administration and complete sensory block (score 2 for all nerves). Duration of sensory block will be defined as the time interval between the complete sensory block and complete resolution of anesthesia (score 0 for all nerves).

Motor block is determined by using the modified Bromage scale (Bromage 0, the patient is able to move the hip, knee and ankle; Bromage 1 when the patient is unable to move the hip but is able to move the knee and ankle, Bromage 2 when the patient is unable to move the hip and knee but able to move the ankle, Bromage 3 when the patient is unable to move the hip, knee and ankle). The interval between the injection and block completion was considered as the onset of motor block. Duration of motor block will be defined as the time interval between the complete motor block and complete resolution of anesthesia. Failed block will be considered if the sensory block and motor block were not achieved after 20 min.

- Pain assessment: Patients will be followed every 2 hours postoperatively till 12 hours for analgesic requirements. Postoperative pain will be assessed via the Visual analogue scale (VAS), and when the VAS is more than 4 the patient will receive 0.25mg/kg nalbuphine.

Inclusion Criteria:

• American Society of Anesthesiologists class I, and II
• Age 20 - 60 years
• Weight between 60 and 80 kilograms
• Height between 160 and 180 centimetres

Exclusion Criteria:

• Participants with contraindications to spinal anesthesia.
• Participant refusal
• Extreme short or tall statures
• Body mass index above 40

A physician assessing outcomes blinded to the nature of the study and will monitor the block density and regression time. Drugs will be given to the patient by an anesthesiologist unaware of the study