Spinal anesthesia is the most consistent block for lower abdomen and lower limb surgical procedures. Over years many drugs have been used as an additive to spinal anesthesia in order to prolong the duration of action and to provide adequate postoperative analgesia.

Dexmedetomidine, a highly selective α2 agonist is rapidly emerging as the choice of additive to spinal anesthesia in view of its property to provide analgesia however, it may be associated with bradycardia which may affect the hemodynamic stability.

Nalbuphine is an opioid with agonist actions in the kappa receptor and antagonist actions in the mu receptor, it produces analgesia and sedation and lesser side effects through antagonism at the mu receptor but, it could be associated with some side effects as: dizziness, bradycardia, nausea, vomiting, and pruritus and may be associated with respiratory depression.

This prospective, double blinded, randomized, controlled study will be held to compare Nalbuphine versus Dexmedetomidine as adjuvants to intrathecal Bupivacaine in spinal anesthesia in patients undergoing lower limb orthopedic surgeries

Inclusion Criteria:

• Age between 20 and 60 years.
• Both genders.
• Patients scheduled for lower limb orthopedic surgeries under spinal anesthesia.
• American society of anesthesiologists (ASA) class I or II.

Exclusion Criteria:

• Patient refusal.
• Age <20 or >60 years.
• Contraindications to spinal anesthesia (e.g. bleeding diathesis, spinal cord deformities, infection at injection site).
• History of allergy to any of the study medications.
• Cases with severe cardiac, renal, or hepatic disease.
• American society of anesthesiologists (ASA) class III, IV.
• Patient on regular analgesics or opioid abuse.
• Patient with peripheral neuropathy.

Intrathecal injectate will be prepared according to the group by an anesthesiologist who is not involved in data collection