Analgesic Potentials of Preoperative Pregabalin,Magnesium Sulphate and Their Combination in Acute Post-thoracotomy Pain

Analgesic Potentials of Preoperative Oral Pregabalin,Intravenous Magnesium Sulphate and Their Combination in Acute Post-thoracotomy Pain.(Randomized,Double-Blind Study)

This study evaluates the effect of giving preoperative adjuvant drug as pregabalin or magnesium sulphate or a combination of both drugs to decrease postoperative morphine consumption and pain intensity in the first 24 hours in postoperative period . quarter of patients receive single dose oral pregabalin 300mg 1 hour preoperatively ,other quarter receive single intravenous Magnesium sulphate 50mg per Kg over 200ml saline over 20 minutes preoperatively , other quarter receive combination of both drugs , the last quarter receive placebo drugs . All patients receive 0.1mg per Kg intravenous morphine sulphate intraoperatively

Magnesium (Mg) acts on N-methyl-D-aspartate (NMDA) receptor as a non-competitive antagonist with antinociceptive effects.

Gabapentin is an alkylated analogue of gammaaminobutyric acid (GABA) developed primarily as an anticonvulsant drug. It was described as an analgesic drug for the treatment of neuropathic pain in the 1990s. Although it is named Gabapentin,it does not bind at the GABA A or GABA B receptor. It binds with high affinity for the α2δ subunit of the presynaptic voltage-gated calcium channels, which reduce calcium-dependent release of pro-nociceptive neurotransmitters in the pain pathways. Pregabalin is a structural analogue of GABA was introduced after Gabapentin. If we used these drugs in combination to opioids preoperatively as preventive analgesia may decrease postoperative opioid consumption and pain intensity.

Inclusion Criteria:

1. ASA status of1 or 2
2. Patients undergoing thoracotomy
3. Body mass index (BMI): Less than forty and more than twenty.

Exclusion Criteria:

- 1. Known sensitivity or contraindication to drugs used in the study. 2. History of psychological disorders and/or chronic pain. 3. Patients receiving medical therapies that are considered to result in tolerance to opioids.

4. Significant liver or kidney diseases that will affects the pharmacokinetics of study drugs.