Effects of morphine and tramadol on somatic and visceral sensory function and gastrointestinal motility after abdominal surgery

Treatment of severe pain from osteoarthritis with slow-release tramadol or dihydrocodeine in combination with NSAID's: a randomised study comparing analgesia, antinociception and gastrointestinal effects

Opioids are increasingly used in the treatment of chronic non-malignant pain. The aim of this open-label, randomised, parallel group study was to compare analgesia and side-effects of two commonly used opioid analgesics, tramadol and dihydrocodeine, in long-acting formulations in 60 osteoarthritis patients with strong pain despite NSAID's. Dose titration based on effect was performed with the respective immediate release solutions given additionally to tramadol 100 mg bid and dihydrocodeine 60 mg bid during the first 4 days of the 1 month treatment. Electrical sensation and pain thresholds over the osteoarthritic joint and at a distant location and gastrointestinal transit times were performed before and during treatment. Thirty patients with pain controlled by NSAID's alone formed the comparator group. Pain intensities at rest and during movement decreased highly significantly with tramadol and dihydrocodeine from median pre-treatment verbal ratings of over 3 (0=none, 4=unbearable) to 1 and below from the second treatment day onwards (ANOVA P<0.0001). Pain at rest was significantly lower with tramadol (ANOVA P=0.04), but ratings were similar during movement. Mean (95% CI) daily doses on days 1 and 28 were 209 (198-220) mg and 203 (191-206) mg of tramadol, and 129 (122-136) mg and 130 (121-134) mg of dihydrocodeine, respectively. Minor side-effects were more common with tramadol (P=0.04). Changes in bowel functions and symptoms were minor with both treatments, but the frequency of defaecation was lower and stools were harder with dihydrocodeine. Orocaecal transit time remained unchanged and similar to controls with both analgesics. Colonic transit times only increased significantly during treatment with dihydrocodeine. Sensation and pain thresholds were lower pre-treatment in both groups than in controls and increased during treatment. These antinociceptive effects were more marked in the tramadol group and distant from the osteoarthritic joint. We conclude rapid pain relief was achieved with both long-acting tramadol and dihydrocodeine with NSAID's in strong osteoarthritis pain. Minimal dose titration was required and side-effects were minor. Tramadol interfered less with intestinal function and showed greater antinociceptive action.

Tramadol--present and future

The atypical opioid, tramadol, has recently been introduced into Australia and New Zealand. Tramadol's efficacy in a wide range of acute and chronic pain states, its multi-formulation availability, and its low serious side-effect potential at high doses and in prolonged therapy, combine to bestow on it a user-friendly profile, for short- and long-term use in hospitals and communities. This paper reviews the following: its formulation and routes of administration; its unique enantiomeric biochemistry and metabolism; its triple mechanisms of action; its pharmacokinetics and pharmacodynamics; its analgesic efficacy compared with other opioids; the indications for its clinical use in a variety of acute and chronic (including cancer) painful states; its specific use in the elderly, in paediatric and in obstetric patients; its adverse event (including drug interaction) and safety profile; its advantages in terms of its relative lack of respiratory depression, major organ toxicity and histamine release, and dependence and abuse potential. The review looks at new uses for this drug and what can be expected in this area in the future.

Tramadol today

Tramadol is a unique analgesic offering moderate, dose-related pain relief through its action at multiple sites. In contrast to pure opioid agonists, it has a low risk of respiratory depression, tolerance and dependence. Troublesome side-effects have been reported, but tramadol has been established as an adjunct to non-steroidal anti-inflammatory drugs in the treatment of moderate postoperative pain and to abolish shivering. It may have advantages in paediatric and day-case surgery and as an adjunct in local anaesthetic techniques. This review provides an evidence-based account of the role of tramadol in modern practice.

Wound closure tramadol administration has a short-lived analgesic effect

PURPOSE

To evaluate the effects of tramadol administration at wound closure on postoperative pain and analgesic requirements in patients undergoing laparoscopic cholecystectomy.

METHODS

In a prospective, randomized, double-blind study 80 patients were allocated into two groups (n = 40 in each) to receive either 200 mg tramadol or placebo i.v. at the time of wound closure. Postoperatively, all patients received tramadol from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr.

RESULTS

Administration of 200 mg tramadol at the time of wound closure was associated with a short-lived (60 min) reduction in pain scores and PCA consumption compared with placebo. Although the time to first request for analgesia after surgery was longer in patients who received tramadol at wound closure, there was no difference between the two groups with respect to pain scores or to the requirements of postoperative analgesia over the next 23 hr. The cumulative PCA consumption of tramadol in 24 hr was 139.4+/-108 and 102.4+/-106 mg in the placebo and tramadol groups, respectively (P = 0.06).

CONCLUSIONS

Wound closure administration of 200 mg tramadol had a short-lived (60 min) analgesic effect but did not affect the long-term pain scores or analgesic requirements after laparoscopic cholecystectomy.

Tramadol: a review of its use in perioperative pain

Tramadol is a synthetic, centrally acting analgesic agent with 2 distinct, synergistic mechanisms of action, acting as both a weak opioid agonist and an inhibitor of monoamine neurotransmitter reuptake. The 2 enantiomers of racemic tramadol function in a complementary manner to enhance the analgesic efficacy and improve the tolerability profile of tramadol. In several comparative, well designed studies, oral and parenteral tramadol effectively relieved moderate to severe postoperative pain associated with surgery. Its overall analgesic efficacy was similar to that of morphine or alfentanil and superior to that of pentazocine. Tramadol provided effective analgesia in children and in adults for both inpatient and day surgery. Tramadol was generally well tolerated in clinical trials. The most common adverse events (incidence of 1.6 to 6.1%) were nausea, dizziness, drowsiness, sweating, vomiting and dry mouth. Importantly, unlike other opioids, tramadol has no clinically relevant effects on respiratory or cardiovascular parameters at recommended doses in adults or children. Tramadol also has a low potential for abuse or dependence.

CONCLUSIONS

The efficacy of tramadol for the management of moderate to severe postoperative pain has been demonstrated in both inpatients and day surgery patients. Most importantly, unlike other opioids, tramadol has no clinically relevant effects on respiratory or cardiovascular parameters. Tramadol may prove particularly useful in patients with poor cardiopulmonary function, including the elderly, the obese and smokers, in patients with impaired hepatic or renal function, and in patients in whom nonsteroidal anti-inflammatory drugs are not recommended or need to be used with caution. Parenteral or oral tramadol has proved to be an effective and well tolerated analgesic agent in the perioperative setting.