الفهرس 
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Abstract
Evaluation of the optimal Preemptive Dose of Gabapentin For postoperative pain relief after mastectomy
Nehal Nouh MD, Azza Youssef MD, Reem El-Kabarity, MD; Amal Rabie, MD; Rafik Atalla M.B.B.Ch, M.Sc
Department Of Anaesthesiology, intensive care and Pain Management,
Faculty of Medicine, Ain Shams University
Breast cancer is a potentially deadly disease affecting one in eight women. It is the most commonly diagnosed form of cancer and the second leading cause of cancer-related death among women. The post mastectomy pain is a major health care issue. Inadequate postoperative pain control has the potential to produce acute neurohumoral changes, neuronal remodeling, and long-lasting psychological and emotional distress, which may lead to prolonged chronic pain states.
Gabapentin, a second generation anticonvulsant drug, 3-alkylated analog of g-aminobutyric acid, is widely used now for treatment of chronic neuropathic pain, diabetic neuropathy, and post-herpetic neuralgia. In addition, perioperative administration of gabapentin is highly effective in reducing postoperative pain scores, opioid requirements and opioid related side effects postoperatively. However, the absorption kinetics of gabapentin are dose dependent and the bioavailability of the drug decreases with increasing the dose, and so the optimal dose of preemptive gabapentin needed to be evaluated.
Gabapentin was designed as a structural analog of the inhibitory neurotransmitter G_Amino Butyric Acid (GABA). Although gabapentin was originally modeled after the structure of GABA, it does not modulate GABA receptor function like conventional GABAergic drugs, and it is inactive at GABA receptors. It is likely that its analgesic effects result from an action at the 1, 1 subunits of the voltage-dependent Ca2 channel (VGCC) for which it has substantial affinity and is upregulated in the dorsal root ganglia and spinal cord after peripheral nerve injury as can be produced by surgical incision. Gabapentin may produce analgesia by binding to an inhibiting presynaptic voltage-dependent Ca2 channels decreasing calcium influx and thereby inhibiting the release of neurotransmitters including glutamate from the primary afferent nerve fibers that synapse on and activate pain responsive neurons in the spinal cord.
A growing body of evidence suggests that pre-operative administration of gabapentin is efficacious for postoperative analgesia, preoperative anxiolysis, and attenuation of the hemodynamic response to laryngoscopy and intubation, and preventing chronic post-surgical pain, postoperative nausea and vomiting, and delirium.
Gabapentin has been used in doses ranging from 300 to 1500mg preemptively for acute pain management, but no clinical trial has yet established the optimal doses of gabapentin for preemptive analgesia. In this work, our concern was to evaluate the optimal preemptive dose of Gabapentin for postoperative pain relief after mastectomy, and its morphine sparing effects during the initial 24hrs postoperatively.
Further Readings:
1. Al-Mujadi H, A-Refai AR, Katzarov MG, Dehrab NA. Batra YK, Al-Qattan AR. Preemptive gabapentin reduces post-operative pain and opioid demand following thyroid surgery. Can J Anesth; 53: 268-73, 2006.
2. Dirks J, Fredensborg BB,Christensen D, Fomsgaard JS, Flyger H. A randomized study of the effects of single-dose gabapentin versus placebo on postoperative pain and morphine consumption after mastectomy. Anesthesiology; 97:560-4, 2002.
3. Fassoulaki A, Triga A, Melemeni A, Sarantopoulos C. Multimodal analgesia with gabapentin and local anesthetics prevent acute and chronic pain after breast surgery for cancer Anesthesia Analgesia; 101: 1427-32, 2005.
4. Pandey CK, Singhal V, Kumar M, Lakra A, Ranjan R, Pal R. Gabapentin provides effective postoperative analgesia whether administered preemptively or post-incision. Can J Anesth; 52:827-31, 2005.
5. Turan A, Karamanlioglu B, Memis D, Usar P, Pamukcu Z, Ture M. The analgesic effects of gabapentin after total abdominal hysterectomy. Anesthesia Analgesia; 98: 1370-3, 2004.