Gabapentin for Prophylaxis Intrathecal Morphine-Induced Pruritus
Status:
Completed
Trial end date:
2010-11-01
Target enrollment:
Participant gender:
Summary
Intrathecal morphine provides good postoperative analgesia for up to 18-24 hour after
administration. Pruritus is the most common side effect of intrathecal morphine, which the
incidence was reported as 20%-100%2 and 63% in Songklanagarind Hospital. Pathophysiology of
opioid-induced pruritus remain unclear and more than one mechanism may be involved in the
development of opioid-induced pruritus, such as, mediated central ยต opioid receptors,
Dopamine (D2) receptors, Serotonin (5-HT3) receptors, prostaglandin system, GABA receptors,
and glycine receptors, so that why opioid-induced pruritus is difficult to manage. Many
medications have been used to treat this side effect included antihistamines, 5-HT3
(serotonin) receptor antagonists, opioid antagonists, opioid agonist-antagonists, propofol,
and nonsteroidal antiinflammatory drugs.
Gabapentin is an anticonvulsant, a structural analog of aminobutyric acid, and currently
approved by the Food and Drug Administration for the treatment of partial seizures and
postherpetic neuralgia. Many studies have shown gabapentin to be effective in the case of
brachioradial pruritus, itch of neuropathic in origin, uremic pruritus, multiple
sclerosis-induced pruritus,cholestatic pruritus, itch produced by burn, and pruritus of
unknown origin. However, there is only one small study in Taiwan shown the effectiveness of
gabapentin 1200 mg in prevention of intrathecal morphine-induced pruritus in orthopedic
surgery, which could reduce incidence of pruritus from 77.5% to 47.5% (38.7% reduction).
Because gabapentin has several side effects especially in high dose such as drowsiness, dry
mouth, headache, unsteadiness, reduced co-ordination or slowed reaction, constipation,
diarrhea, peripheral edema, dizziness, confusion, loss of concentration, weight gain, and
nausea, vomiting, so in our study we decided to reduce the dose of gabapentin. Therefore, we
would like to know if gabapentin in a smaller dose (600 mg) used in the wider range of age
including the elderly can decrease the incidence of intrathecal morphine-induced pruritus in
orthopedic surgery in Songklanagarind Hospital.