|Year : 2008 | Volume
| Issue : 4 | Page : 428
To Evaluate the Role of Gabapentin as Preemptive Analgesic in Patients Undergoing Total Abdominal Hysterectomy in Epidural Anaesthesia
Anil Verma1, Sangeeta Arya1, Sandeep Sahu1, Indu Lata2, HD Pandey3, Harpreet Singh4
1 Lecturer, Dept of Obst & Gynae, R.I.M.S,Etawah,U.P, India
2 Senior Resident, Dept of Obst & Gynae, V.M.M.C & Safdarjung Hospital ,New Delhi, India
3 Professor& Head, Department of Anaesthesiology & Critical Care, G. S. V. M. Medical College, Kanpur, U.P., India
4 P.G.Student, Department of Anaesthesiology & Critical Care, G. S. V. M. Medical College, Kanpur, U.P, India
|Date of Acceptance||03-Jun-2008|
|Date of Web Publication||19-Mar-2010|
Department of Anaesthesiology & Critical Care, G. S. V. M. Medical College, Kanpur, U.P
Source of Support: None, Conflict of Interest: None
Gabapentin, a structural analogue of gamma-amino butyric acid, has been used as an anticonvulsant and antinociceptive drug but its mode of action is not well understood. Gabapentin has been demonstrated in various clinical studies to be of value as preemptive analgesic, and has shown to reduce the postoperative requirement of opioids. This study was conducted to evaluate the role of gabapentin as preemptive analgesic in patients undergoing total abdominal hysterectomy. Fifty patients with ASA grade I and II were assigned to receive 300mg gabapentin or placebo 2hr before surgery. Surgeries were conducted under combined spinal epidural anaesthesia. Post operatively, pain was assessed by visual analogue score (VAS) at 2, 4,8,12 and 24hrs. Patients were given epidural boluses of bupivacaine (0.125%) on demand. Total numbers of epidural boluses during first 24 hrs postoperatively were noted. Patients in gabapentin group have significantly lower VAS score 2, 4,8,12 and 24hrs postoperatively as compared to the placebo (1.3 ± 1.3, 2.3±1.4, 3.2 ± 2.1, 1.8 ± 1.7, 1.2 ± 1.3 vs. 2.1 ± 1.7, 3.2±1.6, 4.4 ± 1.2, 3.3 ± 1.1, 2.1 ± 1.2 respectively; P <0.05). Total numbers of epidural boluses were significantly less in gabapentin group (3.4±1.6 vs. 5.6±2.1, P<0.05). We conclude that preemptive use of gabapentin 300mg orally significantly reduces the number of postoperative epidural bolus requirement and postoperative pain in patients undergoing total abdominal hysterectomy under combined spinal epidural anaesthesia.
Keywords: Gabapentin, Total abdominal hysterectomy, Preemptive analgesia.
|How to cite this article:|
Verma A, Arya S, Sahu S, Lata I, Pandey H D, Singh H. To Evaluate the Role of Gabapentin as Preemptive Analgesic in Patients Undergoing Total Abdominal Hysterectomy in Epidural Anaesthesia. Indian J Anaesth 2008;52:428
|How to cite this URL:|
Verma A, Arya S, Sahu S, Lata I, Pandey H D, Singh H. To Evaluate the Role of Gabapentin as Preemptive Analgesic in Patients Undergoing Total Abdominal Hysterectomy in Epidural Anaesthesia. Indian J Anaesth [serial online] 2008 [cited 2020 May 30];52:428. Available from: http://www.ijaweb.org/text.asp?2008/52/4/428/60657
| Introduction|| |
Gabapentin [1-(aminomethyl)cyclohexane acetic acid]is a structural analog of gamma aminobutyric acid (GABA), which was initially introduced in 1994 as an antiepileptic drug, particularly for partial seizures. It was soon found to be promising in treating neuropathic pain associated with postherpetic neuralgia (PHN) , , post poliomyelitis neuropathy  , and reflex sympathetic dystrophy  . Placebo-controlled clinical trials also have indicated a role of gabapentin in treating pain related to diabetic neuropathy (DNP)  and PHN  . The concept of preemptive analgesia to reduce postoperative pain was founded on a series of successful animal experimental studies that demonstrated central nervous system plasticity and sensitization after nociception  . Preemptive analgesia is defined as an antinociceptive treatment that prevents the establishment of altered central processing of afferent input, which amplifies postoperative pain  . By decreasing the altered central sensory processing, preemptive analgesia is thought to consequently decrease the incidence of hyperalgesia and allodynia after surgery  . Gabapentin has demonstrated analgesic effects in clinical trials as a pre-emptive analgesic and in acute postoperative pain management; however, experience with gabapentin is limited ,, .There has not been a separate study about the pre-emptive use of gabapentin in cases conducted under regional anaesthesia and its effects on requirement on postoperative epidural requirement of local anaesthetics. We therefore designed the present study to investigate whether pre-emptive use of gabapentin 300 mg orally could reduce postopera tive pain and number of epidural boluses in the initial 24 hours in patients undergoing total abdominal hysterectomy.
| Methods|| |
After getting approval from institutional ethical committee. Written and informed consent was taken from each of the patients. Fifty patients of ASA status I an II undergoing total abdominal hysterectomy between age group 20 -60yrs of age were selected for the study. Patients with allergy to gabapentin, suffering from epilepsy, liver disease, renal disease, suffering from any chronic pain syndrome, having psychiatric illness or patients who have taken NSAID in last 48 hrs were excluded from the study.
Assuming that following therapy VAS would reduce by 50%, one would need to enroll 23 patients in each group for the results to be statistically significant at a power of 80% with a level of confidence of 5%. In considering any dropouts, we included 25 patients in each group. The patients were randomly divided into 2 groups with 30 patients in each.
The study design was randomized and doubleblind. Patients were randomly allocated into 2 equal groups of 25 each with the help of a computer-generated table of random numbers. All study medications were given orally with sips of water 2 hour preoperatively by a staff nurse who was not involved in the study. Patients in study Group-G (gabapentin) received tab gabapentin 300mg; whereas in study Group-P (placebo) patients received matching placebo. All patients were premedicated with ranitidine and metoclopramide I.V. 1hr before surgery. Routine monitoring with pulse oximetry, NIBP, ECG, temperature and urine output with an indwelling catheter was initiated in the operation theatre.
All patients were preloaded with 10ml.kg -1 of lactated Ringers' solution and combined spinal epidural were performed at interspace L2-L3 or L3-L4 in sitting position. 4ml of hyperbaric solution of 0.5% bupivaciane was given in the subarachnoid space. After confirmation of the successful blockade and proper height of anaesthesia all patients were sedated with infusion of propofol at rate of 25-50µg.kg -1 .min -1 . propofol infusion was stopped at the beginning of the skin sutures. After surgery patients were shifted to recovery room. Patients were given 12 ml of epidural bupivaciane 0.125% boluses for pain relief on demand. VAS scores were assessed by an independent physician (AV) who was not aware of the group allocation on a scale of 0-10cm (0 mean no pain, 10 equals to worst imaginable pain) after 2, 4, 8, 12 and 24hrs after the surgery at the same time patients were asked for any complication suffered by them. Total numbers of epidural boluses received by each patient were noted. The data were entered into the statistical software package SPSS 9. The mean ± SD from maximum pain scores for all patients in both groups at time intervals of 0-2, 2-4, 4-8, 8-12 and 12-24 hr were calculated. Similarly, epidural bupivaciane 0.125% consumption in each group was calculated. A value of P < 0.05 was considered significant. VAS scores were analyzed with two-factor ANOVA for repeated measures. The total epidural bupivaciane 0.125% consumed in each group (mean ± SD) in 24 hr was compared using an unpaired t test.
| Results|| |
There was no difference in age, sex, body weight, and duration of anesthesia between the two groups [Table 1].
Patients in the Group-G (gabapentin) had significantly lower VAS scores at all times 2, 4, 8, 12 and 24hrs than those in the Group-P (placebo) [Table 2], [Figure 1]. The total number epidural boluses demanded after surgery in the first 24 hr in the Group-G (gabapentin) (3.4±1.6 , mean ± SD) was significantly less than in the Group-P (placebo) ( 5.6±2.1, P<0.05, [Figure 2])
The incidence of adverse effects (nausea 5 vs 4, vomiting 3 vs 4, fatigue 1 vs 0, light headedness 1 vs 0 and dizziness 1 vs 0) was similar in the Group-G (gabapentin) and Group-P (placebo).
| Discussion|| |
In present study we have demonstrated that 300mg of gabapentin taken 2hrs before surgery results in substantial reduction in pain and requirement of the epidural boluses in patients undergoing total abdominal hysterectomy and that gabapentin was not associated with more side effects when compared with placebo.
After a single oral dose of 300 mg, mean maximum plasma concentrations are attained in 2-3 hours. The pre-emptive administration of gabapentin approximately two hours before surgery appears optimal in order to attain maximal plasma concentrations at the time of surgical stimuli. In animal models of nociception, gabapentin reduces hypersensitivity associated with nerve injury, inflammation, and pain after surgery,, . Mechanical hyperalgesia surrounding the wound in post-operative patients, and experimental, heat-induced secondary hyperalgesia share a common mechanism- central neuronal sensitization-that may contribute to some aspects of postoperative pain. Antihyperalgesic drugs such as gabapentin may have a role in postoperative pain. It has also been demonstrated that a 600 mg single dose of gabapentin enhanced the effect of morphine, but side effects appeared in approximately 40% of volunteers when these drugs were used concomitantly.  Another study of 22 human volunteers who received 1,200 mg of gabapentin or placebo in a double-blind, randomized cross-over fashion on two separate study days, demonstrated reduced primary mechanical alloying in acute inflammation following a first degree thermal injury, suggesting that gabapentin had clinical potential in the treatment of postoperative pain.  In another study, gabapentin was shown to reduce the requirement of fentanyl for postoperative pain relief in patients undergoing lumbar discoidectomy  . Gabapentin is well tolerated. It has few side effects and minor interactions with other drugs when used for the treatment of chronic pain  . We did not observe any significant side effects associated with a single oral dose of gabapentin.
In conclusion, single oral dose of gabapentin given 2hrs before surgery provides better pain control as compared to the placebo and also reduces the requirement of epidural boluses in patients undergoing total abdominal hysterectomy with out increase in frequency of side effects.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]