Epidural somatostatin as an analgesic in upper abdominal surgery: a double-blind study

Somatostatin 1-14, a natural occurring neuropeptide (Somiaton), has been reported to have analgesic effects in humans in different painful conditions. The aim of the present study was to investigate if epidural somatostatin produced clinical analgesia to postoperative pain after upper abdominal surgery. In a randomized double-blind controlled study, 40 patients received either 125 micrograms of epidural somatostatin infusions every hour (using a continuous infusion pump: CADD-PCA model 5200 PCX, Pharmacia) or placebo: mannitol (somatostatin inactif ingredient) 2.5 mg during the first 3 postoperative days (plus additional pulses of either substance, 250 micrograms or 5 mg, respectively, according to the level of analgesia needed by the patient). Additional subcutaneous analgesic treatment with 1 mg/kg pethidine chlorhydrate was administered at the patient's request. The degree of pain was quantified with visual analogue scale at baseline, 1 h after the operation and at every 4 h for the next 3 days. Arterial blood gases and spirometry values were determined at different intervals throughout the study period. Somatostatin was significantly better than placebo for pain relief (P < 0.01) and respiratory function preservation (P < 0.05). The total consumption (and ranges) of somatostatin at 24, 48 and 72 h were: 5.2 +/- 1.4 mg (4.0-6.25 mg), 4.2 +/- 0.8 mg (2.2-5.0 mg) and 3.7 +/- 0.4 mg (2.2-4.7 mg) respectively. During the whole study the need for complementary analgesia (pethidine chlorhydrate) was significantly higher in the placebo group: 5.4 +/- 3.5 vs. 2.7 +/- 1.9 (mean +/- SD) P < 0.01, dose/72 h. Side effects were irrelevant and scarce in both groups. The sustained pain relief combined with the respiratory function preservation in the somatostatin group suggests an important role of this drug in postoperative analgesia.