Comparison of buprenorphine and meloxicam for postsurgical analgesia in rats: effects on body weight, locomotor activity, and hemodynamic parameters

Abstract

Buprenorphine is administered to humans and animals for postoperative pain management, although its use is associated with complications. Alternative analgesics, including the nonsteroidal antiinflammatory meloxicam, are available, but information on their postoperative effects is limited. The objective of the present study was to compare buprenorphine (0.03 mg/kg SC twice daily for 3 d) with meloxicam (2 mg/kg SC initial dose followed by 1 mg/kg SC once daily for 2 d) by assessing parameters relating to postsurgical recovery in rats that underwent surgical implantation of radiotelemetric transducers. Rats treated after surgery with buprenorphine showed greater reductions in body weight, food consumption, locomotor activity, and nighttime heart rates than did meloxicam-treated rats. Buprenorphine and meloxicam treatments both had stimulatory effects on mean arterial pressure and daytime heart rate measurements, although effects on nighttime mean arterial pressure were greater in the buprenorphine-treated rats. In summary, the lesser physiologic changes associated with meloxicam, as compared with buprenorphine, suggest that meloxicam offers advantages for use as a postoperative analgesic after laparotomy and radiotelemetric transducer implantation in rats.

Figure 1.

(A) Analgesic treatment affects body weight during the postoperative period; inset, accumulated weight loss (area under the curve) during the early (days 0 to 2), intermediate (days 3 to 5) and late (days 6 to 9) postoperative periods. (B) Correlation between weight loss throughout the 10-d postoperative period and body weight at the time of implantation surgery. BUP, buprenorphine; MEL, meloxicam; *, P < 0.001 compared with the meloxicam group on the same day; †, P < 0.01 compared with preoperative values in the same group; ‡, P < 0.01 compared with preoperative values in the same group. Shaded area indicates analgesic treatment period.

Figure 2.

Analgesic treatment affects food consumption during the postoperative period; inset, mean variation during the early (days 0 to 2), intermediate (days 3 to 5), and late postoperative period. BUP, buprenorphine; MEL, meloxicam; *, P < 0.05 compared with the meloxicam group on the same day; †, P < 0.01 compared with the meloxicam group on the same day; ‡, P < 0.05 compared with postoperative values in the same treatment group; §, P < 0.01 compared with preoperative values in the same treatment group. Shaded area indicates analgesic treatment period.

Figure 3.

(A) Analgesic treatment affects nighttime locomotor activity and, to a lesser extent, (B) daytime locomotor activity in the postoperative period. Insets, mean variation in activity during early (days 0 to 2), intermediate (days 3 to 5), and late (days 6 to 9) postoperative periods. BUP, buprenorphine; MEL, meloxicam; *, P < 0.05 compared with meloxicam group during the same time interval; †, P < 0.01 compared with meloxicam group during the same time interval; ‡, P < 0.05 compared with baseline value (postoperative day 9 or 10) in the same treatment group; §, P < 0.01 compared with baseline value (postoperative day 9 or 10) in the same treatment group. Shaded area indicates analgesic treatment period.

Figure 4.

Analgesic treatment affects (A) nighttime HR, (B) daytime HR, (C) nighttime MAP, and (D) daytime MAP. Insets, mean variation in MAP or HR during early (days 0 to 2), intermediate (days 3 to 5), and late (days 6 to 9) postoperative periods. BUP, buprenorphine; MEL, meloxicam; *, P < 0.05 compared with the meloxicam group during the same time interval; †, P < 0.01 compared with the meloxicam group during the same time interval; ‡, P < 0.05 compared with baseline value (postoperative day 9 or 10) in the same treatment group; §, P < 0.01 compared with baseline value (postoperative day 9 or 10) in the same treatment group. Shaded area indicates analgesic treatment period.