Buprenorphine in postoperative pain: results in 7500 patients

Use of sublingual buprenorphine for pain relief in office hysteroscopy

STUDY OBJECTIVE

To assess the efficacy of sublingual buprenorphine in the relief of pain associated with office hysteroscopy.

DESIGN

Prospective, randomized study (Canadian Task Force classification I).

SETTING

Tertiary medical center.

PATIENTS

One hundred sixty-four women referred for office hysteroscopy from September 2003 through March 2004.

INTERVENTION

Before hysteroscopy, 80 women received a tablet of buprenorphine (group A), and 84 women received a placebo (group B). Their pain sensations were evaluated on a 10-cm visual analog scale, and they were asked about the adverse reactions and level of satisfaction on the following day.

MEASUREMENTS AND MAIN RESULTS

The pain score in group A was 3.3 +/- 1.1, which was similar to 3.2 +/- 1.3 in group B. The pain scores in subgroups of women also were similar within the same group and between the two groups. Thirty-one women (38.8%) in group A reported adverse reactions, including nausea, vomiting, and drowsiness, while none in group B reported any adverse reactions.

CONCLUSION

Office hysteroscopy with a 3.1-mm flexible hysteroscope is a well-tolerated procedure. Sublingual buprenorphine is not helpful in relieving the pain associated with hysteroscopy but is associated with significant adverse reactions.

Buprenorphine: considerations for pain management

New effective analgesics are needed for the treatment of pain. Buprenorphine, a partial mu-opioid agonist which has been in clinical use for over 25 years, has been found to be amenable to new formulation technology based on its physiochemical and pharmacological profile. Buprenorphine is marketed as parenteral, sublingual, and transdermal formulations. Unlike full mu-opioid agonists, at higher doses, buprenorphine's physiological and subjective effects, including euphoria, reach a plateau. This ceiling may limit the abuse potential and may result in a wider safety margin. Buprenorphine has been used for the treatment of acute and chronic pain, as a supplement to anesthesia, and for behavioral and psychiatric disorders including treatment for opioid addiction. Prolonged use of buprenorphine can result in physical dependence. However, withdrawal symptoms appear to be mild to moderate in intensity compared with those of full mu agonists. Overdoses have primarily involved buprenorphine taken in combination with other central nervous system depressants.

[Comparative study of buprenorphine and its combination to ketoprofen or propacetamol for postoperative analgesia in urologic surgery]

OBJECTIVE

To compare the analgesic effect of subcutaneous buprenorphine alone and in combination with propacetamol and ketoprofen following urologic surgery.

STUDY DESIGN

Open randomized clinical trial.

PATIENTS

Sixty ASA II/III patients undergoing urologic surgery.

METHODS

The patients were randomized into three groups to receive either buprenorphine (0.3 mg subcutaneous) on demand (group 1, n = 20), or a combination of buprenorphine (0.3 mg)-propacetamol (2 g)-ketoprofen (100 mg) by intravenous route over 2 hours followed by an infusion of propacetamol (2 g) and ketoprofen (100 mg) at a constant rate over. The remaining 22 hours (group 2, n = 20), or the same loading dose as in group 2 prolonged by a continuous infusion of buprenorphine (0.3 mg), propacetamol (2 g) and ketoprofen (100 mg) over the same period (group 3, n = 20). Visual analogue scale pain scores (0-10) were assessed every hour during the 24 hours of the study. When the VAS score exceeded 5, an additional dose of 0.3 mg of buprenorphine was administered.

RESULTS

Groups were similar for age, surgery, anaesthesia and initial pain levels. Compared to group 1, the onset of analgesia was earlier in groups 2 and 3 at the 1st hour (P < 0.05); the level of analgesia was lower at the 3rd hour (P < 0.05). The maintenance of this analgesia level required constant buprenorphine administration. Buprenorphine requirements were decreased to 56% and 37% in groups 2 and 3 respectively, compared to group 1 (P < 0.05). Incidence of nausea and vomiting was lowered to 15% in group 3 (P < 0.05).

CONCLUSION

A combination of buprenorphine, propacetamol and ketoprofen provides effective postoperative analgesia with a low incidence of nausea and vomiting and decreased requirements of buprenorphine.

Buprenorphine blocks diffuse noxious inhibitory controls in the rat

A C-fibre reflex elicited by electrical stimulation within the territory of the sural nerve was recorded from the ipsilateral biceps femoris muscle in anaesthetised rats. Such reflex responses can be inhibited by applying noxious conditioning stimuli to heterotopic areas of the body. These inhibitory processes have been termed diffuse noxious inhibitory controls. The responses were recorded before, during and after the immersion of the tail in a thermoregulated waterbath (at 50 degrees C) for 1 min. The C-fibre reflex responses were depressed by a maximum of 71 +/- 3% at 45 s after the start of such conditioning stimuli. A dose of 3 mu g/kg buprenorphine completely blocked the inhibition and post-stimulus effects triggered by the heterotopic noxious stimuli. In the 0.3-3 mu g/kg range, buprenorphine increased, in a dose-dependent manner, the magnitude of the inhibition. These doses did not produce any changes in the C-fibre reflex itself. The results are discussed in terms of the mechanisms underlying the analgesic properties of buprenorphine.

Caudal analgesia with buprenorphine for postoperative pain relief in children

Caudal buprenorphine was investigated as a postoperative analgesic in a randomized double blind study in thirty children aged 5-12 years undergoing lower abdominal and lower limb surgery. Comparison was made between two groups of patients, one group receiving plain bupivacaine and the other a combination of plain bupivacaine with buprenorphine. Postoperative analgesia was assessed using a linear analogue scale, and by the response to direct questioning of children using an illustration of sequence of faces. Any untoward side effects and the need for additional analgesics were recorded. The degree and duration of analgesia was far superior in the buprenorphine group and there was a highly significant difference in the requirement of postoperative analgesia between the two groups. There were no major adverse side effects and no motor weakness in either groups, however the incidence of nausea and vomiting was higher in the buprenorphine group. It is concluded that a combination of bupivacaine with buprenorphine administered through the caudal epidural space is a safe and reliable means of providing postoperative pain relief in children for up to 24 h.

[Risk evaluation of oxygen desaturation after buprenorphine or morphine administration during the early postoperative period]

The purpose of this study, conducted in a PACU in the early recovery period of orthopaedic procedures under general anaesthesia, was to compare the time course of O2 arterial saturation (SpO2), measured by pulse oximetry, after the intramuscular administration of either buprenorphine (0.30 mg) or morphine (10 mg). The rate of patients who had an episode of O2 desaturation (defined as a SpO2 under 95%) was similar in both groups: 73% after buprenorphine vs 67% after morphine. The cumulative duration of desaturation episodes was higher following buprenorphine (p < 10(-5). Finally, in patients who had at least one episode of arterial desaturation, the mean duration of these episodes was identical in both groups. However the average number of episodes per patient was significantly higher in the buprenorphine group. These results should lead us to be cautious with the use of buprenorphine during the early recovery period, especially as this as this agent has specific characteristics such as a long duration of action and resistance to naloxone.

Further studies on the antinociceptive activity and respiratory effects of buprenorphine in sheep

The thermal and mechanical analgesic profile of buprenorphine at a dose rate of 1.5 micrograms/kg i.v. was investigated in five sheep. This dose produced significant analgesia for 40 min against the thermal stimulus, but no mechanical antinociception. A higher dose rate of 12 micrograms/kg also failed to produce antinociception to a mechanical stimulus. In addition, the effect of the drug (6 micrograms/kg) on respiratory gas tensions was determined and no significant changes were observed.

Postoperative analgesia in children who have genito-urinary surgery. A comparison between caudal buprenorphine and bupivacaine

A study conducted on 40 children, aged 1-11 years, who had genito-urinary surgery compared the quality and duration of analgesia after caudal blocks in two groups of patients. Group 1 (n = 20) received caudal bupivacaine 0.25% and group 2 (n = 20) caudal buprenorphine 4 micrograms/kg; each received 0.5 ml/kg body weight. Patients were operated on under general anaesthesia. Postoperative behaviour and severity of pain were measured on a 3-point scale. The results indicate that caudal buprenorphine provides excellent postoperative analgesia in children comparable to caudal bupivacaine in the early postoperative period. Buprenorphine proved better in the late postoperative period. Analgesia lasted from 20 hours to more than 24 hours after caudal buprenorphine with fewer side effects.

Spinal buprenorphine for postoperative analgesia after caesarean section

Two doses of intrathecal buprenorphine for postoperative analgesia have been compared. Forty-five women undergoing elective caesarean section under spinal anaesthesia were randomly divided into three groups. Group A (controls, n = 15) received hyperbaric bupivacaine; Groups B and C received the same but with the addition of 0.03 mg or 0.045 mg buprenorphine, respectively. Patients receiving buprenorphine had a longer pain-free interval than the controls (P less than 0.01). Within the buprenorphine groups, patients receiving the higher dose had a longer effect (420 min s.d. 24) than those receiving the lower dose (173 min s.d. 31) (P less than 0.01) without any increase in side-effects.

Epidural sufentanil versus intramuscular buprenorphine for postoperative analgesia. A double-blind comparative trial

Epidural sufentanil 50 micrograms was compared with intramuscular buprenorphine 0.3 mg for postoperative pain relief. Patients were assigned randomly to one of two treatment groups and received both an intramuscular and epidural injection, one of which was a placebo. Onset of pain relief was faster and quality of analgesia superior during the first 2 hours in the patients who received epidural sufentanil but the duration of analgesia was longer in the buprenorphine group. Cardiovascular variables remained stable in all patients and no respiratory depression was observed. Side effects were more frequent following buprenorphine.

A double-blind comparison of the relative efficacy, side effects and cost of buprenorphine and morphine in patients after cardiac surgery

The analgesic efficacy, side effects and cost of administration of regimens of intravenous buprenorphine and intravenous morphine were compared in a randomized double-blind trial performed during the first 24 h after cardiac surgery. Seven patients received buprenorphine by intermittent intravenous injection and six received morphine by continuous infusion. Both these regimens provided good analgesia for the entire 24 h period, with only mild pain at rest and moderate pain on vigorous coughing. Both regimens also produced mild respiratory depression but this was not of clinical importance: the mean arterial PCO2 in both groups was less than 45 mmHg after extubation. The major difference between drugs in the clinical setting was the ease of administration. Buprenorphine had no narcotic code restriction and could be given by intermittent intravenous injection, whereas morphine required checking and handling as a restricted drug and administration by continuous intravenous infusion. When labour and material costs were computed, over the first 24 postoperative hours, it cost $19.76 per patient to administer morphine, but only $3.16 to administer buprenorphine. Thus the use of buprenorphine injections for the first 24 h after cardiac surgery produced pain relief and respiratory depression comparable to that produced by a morphine infusion, but with a significant cost saving in terms of labour and materials.

Peroperative buprenorphine: do high dosages shorten analgesia postoperatively?

Fifty-two patients undergoing biliary surgery were investigated in a prospective randomized study, in which they received buprenorphine 10, 20, 30, and 40 micrograms X kg-1, respectively, as sole intravenous analgesic as a bolus 15 min before induction of anaesthesia. The anaesthetic was uneventful in all four groups, although when receiving 10 and 20 micrograms X kg-1 almost two-thirds of the patients needed supplemental analgesics during the operation. When receiving buprenorphine in the dosage of 30 and 40 micrograms X kg-1, 50% of the patients requested an analgesic within 5 min of extubation. In contrast, when receiving 10 and 20 micrograms X kg-1 none of the patients requested an analgesic within 1 h of the operation. These findings accord to a certain extent with the presence of a bell-shaped dose-response curve for buprenorphine in humans.

Epidural buprenorphine for postoperative analgesia. A controlled comparison with epidural morphine

In a double-blind controlled study, epidural buprenorphine 0.3 mg was compared with 4 mg of epidural morphine for postoperative pain relief the first 24 hours after major orthopaedic surgery. The degree of analgesia was equal and satisfactory in both groups. Duration of action was 620 minutes with buprenorphine and 580 minutes with morphine, which was not significantly different. The only serious side effects were recorded in the morphine group, with two patients complaining of pruritus and five of urinary retention. In conclusion, epidural buprenorphine did not offer any advantages in preference to morphine for postoperative pain relief following orthopaedic surgery.

Longterm treatment with epidural opioids. A retrospective study comprising 150 patients treated with morphine chloride and buprenorphine

During a 2-year period, 150 patients were treated with epidural opioids for more than 7 days; 89 received morphine and 61 buprenorphine. In 16 cases, medication was changed from morphine to buprenorphine, and in 6 from buprenorphine to morphine. In 19 patients in each group, the disease process was benign. The median daily dose of morphine was 17 mg given by an average of 2.9 injections; the corresponding figures in the buprenorphine group were 1.3 mg and 2.6 injections. The mean duration of treatment was 49 days (7-397) in the morphine group and 53 days (7-262) in the buprenorphine group. Satisfactory pain relief was achieved in 40 (45%) patients who received morphine and 41 (67%) patients given buprenorphine. Altering medication from morphine to buprenorphine improved analgesia in 32% of patients, while the reverse improved pain relief in a further 46% of the patients. Side effects were reported in 46% of patients given morphine and 20% given buprenorphine. Seventy-one patients were treated on an outpatient basis. In these cases, buprenorphine was administered for 89% of the total duration of treatment and morphine chloride for 52%.

Multidose/observational, comparative clinical analgetic evaluation of buprenorphine

Ninety-eight patients completed a double-blind, multidose, randomized parallel study in which buprenorphine (Temgesic) was compared to morphine. Drugs were administered at approximately equipotent intramuscular doses for a maximum of three days for the relief of moderate to severe postoperative pain. The two drugs exhibited similar profiles with pain relief evident at 1/2 hour, peaking at 1 hour, and decreasing to slight relief at 4-5 hours, with no significant differences for time to remedication. The most frequent side effect was somnolence. One patient suffered sudden chest pain shortly after an injection of morphine, and one patient had moderate hypoventilation after buprenorphine; both patients recovered uneventfully. Overall, both drugs provided good or excellent analgesia in 80 per cent of the patients in this unique multidose/observational study. Thus, these data and the reported lack of withdrawal symptoms and the absence of physical dependence liability suggest that buprenorphine may have a role in the management of chronic pain.