This study was designed to qualitatively evaluate the
analgesic actions of intrathecal
neostigmine alone and with intravenous (IV) N-butyl-
scopolamine on somatic and
visceral pain. Twenty-seven patients scheduled for both
tubal ligation and vaginoplasty were divided into three groups. Patients received a standard
anesthetic with
thiopental,
atracurium, and N2O/O2/
enflurane. N-butyl-
scopolamine, 20 mg, or saline was administered as a 2-mL IV bolus 20 min before the end of the
surgical procedure. The control group (CG) received spinal and IV saline; the
neostigmine group (NG), spinal
neostigmine and IV saline; and the
neostigmine-N-butyl-
scopolamine group (NSG), spinal
neostigmine and IV N-butyl-
scopolamine. Postoperatively, patients assessed their
pain on a 10-cm visual analog scale (VAS). The CG had both visceral and
somatic pain at the first 30-min assessment, and all patients requested
morphine. Patients from the NG had only
visceral pain from the first assessment; however, they had lower VAS scores (P = 0.026) and requested less
morphine (P = 0.037). Patients from the NSG were
pain free during all assessment times (P < 0.0001).
Neostigmine was more effective for
somatic pain than
visceral pain. N-butyl-
scopolamine administration acted peripherally as an effective
complement for treatment of
visceral pain, reflecting an association between central
cholinergic effects and peripheral
anticholinergic effects in the treatment of visceral
postoperative pain.