Comparison of Mirtazapine,Gabapentin and Ondansetron to prevent intrathecal morphine induced pruritus

Abstract

OBJECTIVE:Antagonism of the central nervous system inhibitor neurotransmitter gamma-Aminobutyric acid (GABA) or serotonergic system activation is an important factor in the pathogenesis of intrathecal morphine-induced pruritus. This study tested the hypothesis that preoperative use of ondansetron, gabapentin or mirtazapine can prevent morphine-induced pruritus.METHODS:We randomly allocated 80 patients of American Society of Anesthesiology (ASA) classification I and II physical status who were to undergo unilateral inguinal hernia or pilonidal sinus operations under spinal anesthesia into 4 equal groups. The first 3 groups received oral doses of 30 mg mirtazapine, 8 mg ondansetron, and 1200 mg gabapentin at 2 hours, 10 minutes, and 1 hour before surgery, respectively, and the fourth group was given a placebo. All patients received intrathecal injection of 15 mg of 0.5% hyperbaric bupivacaine and 0.2 mg morphine. Pruritus was evaluated at 0, 3, 6, 9, 12, and 24 hours after intrathecal morphine administration, and details of presence, onset time, duration, localization, and severity of pruritus were recorded.RESULTS:Incidence of pruritus was significantly more frequent in the placebo group compared to ondansetron, gabapentin, and mirtazapine groups (70%, 55%, 35%, and 35%, respectively). In general, onset of pruritus was between 2 and 6 hours after intrathecal morphine injection; however, onset in the gabapentin group (mean±SD: 4.75±2.7 hours; p=0.019) was delayed compared to other groups. It was observed that pruritus persisted relatively longer in the ondansetron and placebo groups (mean±SD: 6±3.08; 5.82±2.96 hours, respectively; p=0.047). No statistical determination was made regarding location of pruritus. Severity of pruritus was greater in the placebo group (p=0.0001). Necessity for antipruritic treatment was not statistically significantly different between groups.CONCLUSION:Incidence and severity of intrathecal morphine-induced pruritus decreased with use of each of all 3 drugs compared to placebo.

Intrathecal hydrophilic opioids for abdominal surgery: a meta-analysis, meta-regression, and trial sequential analysis

“…The duration of pruritus was only investigated in the study of Boonmak and colleagues 35 over 48 h, which showed a decline of incidence after 24 h. This is in accordance with other studies. 3 , 73 …”

Evaluation of Therapies for Peripheral and Neuraxial Opioid-induced Pruritus based on Molecular and Cellular Discoveries

“…Preoperative gabapentin (1,200 mg per os ) has been found to significantly delay the onset and reduce the incidence and severity of intrathecal morphine–induced pruritus in patients undergoing orthopedic surgery 162 and prolong the onset of pruritus in patients receiving spinal morphine for unilateral hernia repair. 120 However, a lower dose (600 mg) was not found to significantly decrease the incidence of pruritus compared to placebo and was associated with urinary retention. 163 Further pharmacologic studies in preclinical and clinical models are necessary to characterize the mechanism of action of gabapentin within the nervous system.…”