Cyclooxygenase inhibition for postoperative analgesia

Synthesis of Sugar and Nucleoside Analogs and Evaluation of Their Anticancer and Analgesic Potentials

Chemical modification of sugars and nucleosides has a long history of producing compounds with improved selectivity and efficacy. In this study, several modified sugars (2–3) and ribonucleoside analogs (4–8) have been synthesized from α-d-glucose in a total of 21 steps. The compounds were tested for peripheral anti-nociceptive characteristics in the acetic acid-induced writhing assay in mice, where compounds 2, 7, and 8 showed a significant reduction in the number of writhes by 56%, 62%, and 63%, respectively. The compounds were also tested for their cytotoxic potential against human HeLa cell line via trypan blue dye exclusion test followed by cell counting kit-8 (CCK-8) assay. Compound 6 demonstrated significant cytotoxic activity with an IC50 value of 54 µg/mL. Molecular docking simulations revealed that compounds 2, 7, and 8 had a comparable binding affinity to cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. Additionally, the bridged nucleoside analogs 7 and 8 potently inhibited adenosine kinase enzyme as well, which indicates an alternate mechanistic pathway behind their anti-nociceptive action. Cytotoxic compound 6 demonstrated strong docking with cancer drug targets human cytidine deaminase, proto-oncogene tyrosine-protein kinase Src, human thymidine kinase 1, human thymidylate synthase, and human adenosine deaminase 2. This is the first ever reporting of the synthesis and analgesic property of compound 8 and the cytotoxic potential of compound 6.

Postoperative pain management

Postoperative pain is a very important issue for several patients. Indifferent of the surgery type or method, pain management is very necessary. The relief from suffering leads to early mobilization, less hospital stay, reduced hospital costs, and increased patient satisfaction. An individual approach should be applied for pain control, rather than a fix dose or drugs. Additionally, medical, psychological, and physical condition, age, level of fear or anxiety, surgical procedure, personal preference, and response to agents given should be taken into account. The major goal in the management of postoperative pain is minimizing the dose of medications to lessen side effects while still providing adequate analgesia. Again a multidisciplinary team approach should be pursued planning and formulating a plan for pain relief, particularly in complicated patients, such as those who have medical comorbidities. These patients might appear increase for analgesia-related complications or side effects.

Peri- and postanalgesic properties of lidokain, lornoxicam, and nitroglycerine combination at intravenous regional anesthesia

Background. This study was conducted to compare and evaluate the effect of adding lornoxicam or nitroglycerine as adjuncts to lidocaine in intravenous regional anesthesia (IVRA). Methods. 60 patients were randomly separated into three groups, lidocaine group (group L), lidocaine + lornoxicam group (group LL), and lidocaine + lornoxicam + transdermal nitroglycerine group (group LL-N). Hemodynamic parameters, sensory and motor blocks onset, and recovery times were recorded. Analgesic consumption for tourniquet pain and postoperative period were recorded. Results. Sensory block onset times and motor block onset times were shorter in the LL-N and LL groups compared with L group. Sensory block recovery time and motor block recovery time were prolonged in the LL and LL-N groups compared with group L. The amount of fentanyl required for tourniquet pain was less in group LL and group LL-N when compared with group L. VAS scores of tourniquet pain were higher in group L compared with the other study groups. Postoperative VAS scores were higher for the first 4 hours in group L compared with the other study groups. Conclusion. The adjuvant drugs (lornoxicam or TNG) when added to lidocaine in IVRA were effective in improving the overall quality of anesthesia, reducing tourniquet pain, increasing tourniquet tolerance, and improving the postoperative analgesia.

Effects of carprofen or meloxicam on selected haemostatic variables in miniature pigs after orthopaedic surgery

The aim of the study was to detect and compare the haemostatic variables and bleeding after 7‑days administration of carprofen or meloxicam in clinically healthy miniature pigs. Twenty-one clinically healthy Göttingen miniature pigs were divided into 3 groups. Selected haemostatic variables such as platelet count, prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, serum biochemical variables such as total protein, bilirubin, urea, creatinine, alkaline phosphatase, alanine aminotransferase and gamma-glutamyltransferase and haemoglobin, haematocrit, red blood cells, white blood cells and buccal mucosal bleeding time were assessed before and 7 days after daily intramuscular administration of saline (1.5 ml per animal, control group), carprofen (2 mg·kg-1) or meloxicam (0.1 mg·kg-1). In pigs receiving carprofen or meloxicam, the thrombin time was significantly increased (p< 0.01) compared to the control group. In animals receiving carprofen, serum urea and creatinine were significantly decreased, compared to the control (p< 0.01) or meloxicam (p< 0.05) groups. In pigs receiving meloxicam, serum urea was significantly decreased (p< 0.05) compared to the control group. Significant differences were not detected in other haemostatic, biochemical variables or bleeding time compared to other groups or to the pretreatment values. Intramuscular administration of carprofen or meloxicam in healthy miniature pigs for 7 days causes sporadic, but not clinically important changes of selected haemostatic variables. Therefore, we can recommend them for perioperative use, e.g. for their analgesic effects, in orthopaedic or other surgical procedures without increased bleeding.

Preemptive analgesic effects of midazolam and diclofenac in rat model

The aim of the present study was to investigate the preemptive analgesic effects of intraperitoneally administrated midazolam and diclofenac, before acute and inflammatory induced pain in rat model. One hundred twenty-eight (n=8 in each group) male Sprague Dawley rats were included in the study. Paw movements in response to thermal stimulation or paw flinching in response to formalin injection were compared after midazolam (0.1, 1, 5 and 10 mg/kg) and diclofenac (10 mg/kg), intraperitoneal administration. Saline was used as a control. Preemptive analgesic effect was significant in both tests when diclofenac and midazolam was administrated before the pain stimuli (p<0.01 and p<0.001). Intraperitoneal injection of midazolam in doses 5 and 10 mg/kg, increase the response time in hot plate test and decrease the number of flinches in formalin test (p<0.01 vs. p<0.001). ED50 of midazolam (with diclofenac) in hot plate test was 2.02 mg/kg (CI95% =-3.47-5.03 mg); and, 0.9 mg/kg (CI95% =-0.87-4.09 mg) in phase I and 0.7 mg/kg (CI95% = 0.48-6.63 mg) in phase II, in formalin test.Intraperitoneally administered midazolam and diclofenac had preemptive analgesic effects on acute thermal, and inflammatory induced pain in rats.

Effect of perzinfotel and a proprietary phospholipase A(2) inhibitor on kinetic gait and subjective lameness scores in dogs with sodium urate-induced synovitis

OBJECTIVE

To investigate the ability of perzinfotel (an N-methyl-d-aspartate receptor antagonist) and a proprietary phospholipase A(2) (PLA(2)) inhibitor to attenuate lameness in dogs with sodium urate (SU)-induced synovitis.

ANIMALS

8 adult dogs.

PROCEDURES

A blinded 4-way crossover study was performed. Dogs received perzinfotel (10 mg/kg), a proprietary PLA(2) inhibitor (10 mg/kg), carprofen (4.4 mg/kg; positive control treatment), or no treatment (negative control treatment). On the fourth day after initiation of treatment, synovitis was induced via intra-articular injection of SU 1 hour before administration of the last treatment dose. Ground reaction forces were measured and clinical lameness evaluations were performed before (baseline [time 0]) and 2, 4, 6, 8, 12, and 25 hours after SU injection. There was a 21-day washout period between subsequent treatments. Data were analyzed via repeated-measures ANOVAs.

RESULTS

Peak vertical force (PVF) and vertical impulse (VI) values for negative control and perzinfotel treatments were significantly lower at 2 and 4 hours, compared with baseline values. Values for PVF and VI for the PLA(2) inhibitor and positive control treatments did not differ from baseline values at any time points. Between-treatment comparisons revealed significantly higher PVF and VI values for the positive control treatment than for the negative control and perzinfotel treatments at 2 and 4 hours. Values for VI were higher for PLA(2) inhibitor treatment than for negative control treatment at 2 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

Perzinfotel did not significantly alter SU-induced lameness. The proprietary PLA(2) inhibitor attenuated lameness but not as completely as did carprofen.

Postoperative analgesia in impacted third molar surgery: the role of preoperative diclofenac sodium, paracetamol and lornoxicam

OBJECTIVE

The aim of this study was to compare the postoperative analgesic effects of preoperative intravenous (i.v.) paracetamol, diclofenac sodium and lornoxicam (nonsteroidal anti-inflammatory drugs).

SUBJECTS AND METHODS

Sixty patients with impacted third molar who underwent surgical removal were randomly allocated into three groups: group P (n = 20), group D (n = 20) and group L (n = 20). Group P received preoperatively 1 g paracetamol i.v., group D 75 mg diclofenac sodium i.m. and group L 8 mg lornoxicam i.v. Postoperative pain intensity, additional consumption of analgesics postoperatively and postoperative complications were compared among groups.

RESULTS

The groups were comparable for pain scores (p > 0.05). Maximum pain scores were recorded in postoperative 4th h in all groups (group L 22, 14-44 mm; group P 24, 13-43 mm; group D 14, 10-24 mm, p = 0.117). Patients experienced high satisfaction scores which were comparable among groups (group L 85, 75-100 mm; group P 87, 70-95 mm; group D 84, 77-98 mm, p = 0.457).

CONCLUSION

Preoperative intramuscular diclofenac, intravenous paracetamol and lornoxicam effectively decreased the pain scores. The patients were satisfied with the three postoperative pain management regimens.

Minimizing the source of nociception and its concurrent effect on sensory hypersensitivity: an exploratory study in chronic whiplash patients

Background

The cervical zygapophyseal joints may be a primary source of pain in up to 60% of individuals with chronic whiplash associated disorders (WAD) and may be a contributing factor for peripheral and centrally mediated pain (sensory hypersensitivity). Sensory hypersensitivity has been associated with a poor prognosis. The purpose of the study was to determine if there is a change in measures indicative of sensory hypersensitivity in patients with chronic WAD grade II following a medial branch block (MBB) procedure in the cervical spine.

Methods

Measures of sensory hypersensitivity were taken via quantitative sensory testing (QST) consisting of pressure pain thresholds (PPT's) and cold pain thresholds (CPT's). In patients with chronic WAD (n = 18), the measures were taken at three sites bilaterally, pre- and post- MBB. Reduced pain thresholds at remote sites have been considered an indicator of central hypersensitivity. A healthy age and gender matched comparison group (n = 18) was measured at baseline. An independent t-test was applied to determine if there were any significant differences between the WAD and normative comparison groups at baseline with respect to cold pain and pressure pain thresholds. A dependent t-test was used to determine whether there were any significant differences between the pre and post intervention cold pain and pressure pain thresholds in the patients with chronic WAD.

Results

At baseline, PPT's were decreased at all three sites in the WAD group (p < 0.001). Cold pain thresholds were increased in the cervical spine in the WAD group (p < 0.001). Post-MBB, the WAD group showed significant increases in PPT's at all sites (p < 0.05), and significant decreases in CPT's at the cervical spine (p < 0.001).

Conclusions

The patients with chronic WAD showed evidence of widespread sensory hypersensitivity to mechanical and thermal stimuli. The WAD group revealed decreased sensory hypersensitivity following a decrease in their primary source of pain stemming from the cervical zygapophyseal joints.

Effect of rectal diclofenac in reducing postoperative pain and rescue analgesia requirement after cardiac surgery

BACKGROUND

Adequate analgesic medication is mandatory after coronary artery bypass grafting (CABG) surgery. The aim of this study was to assess the analgesic efficacy, side effects, and need for rescue analgesia after CABG surgery comparing diclofenac and placebo rectal suppository.

METHODS

Thirty-seven consenting adults undergoing elective CABG surgery were randomly assigned in a double-blind fashion to receive either rectal diclofenac 100 mg (Group 1, n = 19) or placebo suppository (Group 2, n = 18) postoperatively, just after extubation. Both groups were given intravenous tramadol as a rescue analgesic. Pain scores in the two groups were assessed on a 10-cm visual analog scale at 0, 0.5, 1, 1.5, 2, 6, 12, 18, and 24 hours after suppository administration. Rescue analgesic consumption, sedation, nausea, and vomiting in both the groups were also recorded.

RESULTS

Twenty-four-hour tramadol consumption in Group 1 was 92.5 +/- 33.5 mg compared to 157.5 +/- 63.4 mg in Group 2 (P = 0.002). Patients in the placebo group had significantly greater pain scores 1.5 to 12 hours after extubation. Group 1 patients were significantly more awake compared to Group 2 (P < 0.05). The incidence of postoperative nausea was less in Group 1 than in Group 2 (P = 0.001). Though not statistically significant, three patients in Group 2 each had a single episode of vomiting, whereas no patient had vomiting in Group 1.

CONCLUSION

Rectal diclofenac suppository with tramadol provides adequate pain relief after cardiac surgery, and also reduces tramadol consumption and side effects commonly associated with tramadol.

Current interventions and approaches to postoperative pain management

Some degree of pain accompanies all surgical procedures. Current evidence informs us that patients will experience significant physiological and psychological effects if this pain is not adequately treated. These effects can cause serious harm, delay recovery from surgery, and in some cases lead to persistent post-surgical chronic pain. This article briefly discusses the importance of assessing patients preoperatively and highlights how some patients will have risk factors which may lead them to experience severe postoperative pain. Approaches to postoperative pain control are focused on ways to address the inter-patient differences in response to pain and treatments and avoid periods of ineffective pain relief. A review of the commonly used analgesics, paracetamol, non-steroidal anti-inflammatory drugs, opioids and local anaesthetics, and methods of administration, is included. The final section provides a short review of emerging trends in acute pain therapy and the implications for improving patient care.

Prospective evaluation of pain and analgesic use following major elective intracranial surgery

OBJECT

Opioid administration after major intracranial surgery is often limited by a presumed lack of need and a concern that opioids will adversely affect the postoperative neurological examination. The authors conducted a prospective study to evaluate the incidence, severity, and treatment of postoperative pain in patients who underwent major intracranial surgery.

METHODS

One hundred eighty-seven patients (77 men and 110 women, mean age 52 +/- 15 years, mean weight 78.1 +/- 19.9 kg) underwent either supratentorial (129 patients) or infratentorial (58 patients) procedures. Sixty-nine percent of the patients reported experiencing moderate to severe pain (> or =4 on a 0-10 scale) during the 1st postoperative day. Pain scores greater than or equal to 4 persisted in 48% on the 2nd postoperative day. Approximately 80% of patients were treated with acetaminophen on the 1st postoperative day, whereas opioids (primarily intravenous fentanyl) were administered to 58%. Compared with patients who underwent supratentorial procedures, those who underwent infratentorial procedures reported more severe pain at rest (mean score 4.9 +/- 2.2 compared with 3.8 +/- 2.6; p = 0.015) and with movement (mean score 6.3 +/- 2.6 compared with 4.5 +/- 2.7; p < 0.001) on the 1st postoperative day. On both the 1st and 2nd postoperative days, patients who underwent infratentorial procedures received greater quantities of opioid (p < or = 0.019) and nonopioid (p < or = 0.013) analgesics than those who underwent supratentorial procedures. Patients' dissatisfaction with analgesic therapy was significantly associated with elevated pain levels on the first 2 postoperative days (p < 0.001).

CONCLUSIONS

In contrast to prevailing assumptions, the study findings reveal that most patients undergoing elective major intracranial surgery will experience moderate to severe pain for the first 2 days after surgery and that this pain is often inadequately treated.

Central Hypersensitivity in Chronic Pain: Mechanisms and Clinical Implications

The available literature consistently shows increased pain sensitivity after sensory stimulation of healthy tissues in patients who have various chronic pain conditions. This indicates a state of hypersensitivity of the CNS that amplifies the nociceptive input arising from damaged tissues. Experimental data indicate that central hypersensitivity is probably induced primarily by nociceptive input arising from a diseased tissue. In patients, imbalance of descending modulatory systems connected with psychologic distress may play a role. There is experimental support in animal studies for the persistence of central hypersensitivity after complete resolution of tissue damage. This is particularly true for neuropathic pain conditions, whereby potentially irreversible plasticity changes of the CNS have been documented in animal studies. Whether such changes are present in musculoskeletal pain states is at present uncertain. Despite the likely importance of central hypersensitivity in the pathophysiology of chronic pain, this mechanism should not be used to justify the lack of understanding on the anatomic origin of the pain complaints in several pain syndromes, which is mostly due to limitations of the available diagnostic tools. Treatment strategies for central hypersensitivity in patients have been investigated mostly in neuropathic pain states. Possible therapy modalities for central hypersensitivity in chronic pain of musculoskeletal origin are largely unexplored. The limited evidence available and everyday practice show, at best, modest efficacy of the available treatment modalities for central hypersensitivity. The gap between basic knowledge and clinical benefits remains large and should stimulate further intensive research.

A randomized, placebo-controlled study of rofecoxib with paracetamol in early post-tonsillectomy pain in adults

BACKGROUND AND OBJECTIVE

Effective and early treatment of postoperative pain and nausea have become pivotal for the early discharge of patients after tonsillectomy. Opioid-based analgesia is standard practice but the use of non-steroidal anti-inflammatory drugs is discouraged due to their platelet inhibiting properties. The cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drugs are effective analgesics and do not affect platelet function. We hypothesized that premedication with cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drug in addition to paracetamol would provide effective analgesia and decrease opioid consumption during early recovery from tonsillectomy.

METHODS

In a randomized, placebo-controlled study of adult tonsillectomy patients (n=40) one group (R-group; n=20) was premedicated with paracetamol 1.5 g and rofecoxib 50 mg and a control group (P-group; n=20) was premedicated with paracetamol 1.5 g and placebo. Morphine was used as rescue medication. Postoperative (24 h) pain scores (0--10), morphine consumption as well as intraoperative blood loss were recorded.

RESULTS

We found no overall difference in pain scores between the groups but significantly more patients in the placebo group had pain scores >5 within the first 8 h. The rofecoxib group consumed less morphine during the first 12 h. A lower intraoperative blood loss was observed in the rofecoxib group.

CONCLUSION

Our results suggest an early although clinically minor analgesic benefit of the addition of a cyclo-oxygenase-2 selective non-steroidal anti-inflammatory drug to paracetamol as premedication for adult tonsillectomy.

Minimal impact urethroplasty allows same-day surgery in most patients

OBJECTIVES

To present our evaluation of the safety and feasibility of decreasing the impact of anterior urethroplasty by minimizing the surgery time, maximizing adjuvant pain therapy, and using anesthetic agents that decrease the incidence and severity of side effects, which allows most patients to leave the hospital comfortably within 4 hours of surgery.

METHODS

A retrospective chart review of 54 consecutive anterior urethroplasty patients from August 2000 to August 2004 (34 anterior anastomotic and 20 ventral onlay buccal mucosal graft urethroplasty) was performed.

RESULTS

Historically, 27% of patients had undergone same-day surgery (SDS). After the initiation of minimal impact surgery and early discharge, 85% did so. All but one admission was planned (1 patient [2%] had hypotension in the recovery room and was admitted). No postoperative readmissions or emergency room visits occurred. The admitted patients had comparable stricture length to, but slightly older age (49 years compared with 42 years) than, the SDS patients. The perioperative complications were mild (small wound gap, small scrotal hematoma) and were seen in 5% of SDS patients and 0% of admitted patients. Late complications (chordee, mild erectile dysfunction, and urinary tract infection) were seen in 19% of SDS patients and 18% of admitted patients. The incidence of recurrences after a mean follow-up of 27 months was comparable (3% for the SDS and 6% for the admitted group).

CONCLUSIONS

Decreasing the impact of urethroplasty surgery allows safe early discharge for most patients. Unexpected admissions were uncommon, and we continue to plan for admission only for the extremely elderly, those with severe comorbidities, and those expected to undergo lengthy (longer than 5 hours) surgery.

A procedure-specific systematic review and consensus recommendations for postoperative analgesia following laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy has advantages over the open procedure for postoperative pain. However, a systematic review of postoperative pain management in this procedure has not been conducted.

METHODS

A systematic review was conducted according to the guidelines of the Cochrane Collaboration. Randomized studies examining the effect of medical or surgical interventions on linear pain scores in patients undergoing laparoscopic cholecystectomy were included. Qualitative and quantitative analyses were performed. Recommendations for patient care were derived from review of these data, evidence from other relevant procedures, and clinical practice observations collated by the Delphi method among the authors.

RESULTS

Sixty-nine randomized trials were included and 77 reports were excluded. Recommendations are provided for preoperative analgesia, anesthetic and operative techniques, and intraoperative and postoperative analgesia.

CONCLUSIONS

A step-up approach to the management of postoperative pain following laparoscopic cholecystectomy is recommended. This approach has been designed to provide adequate analgesia while minimizing exposure to adverse events.

Preoperative use of selective COX-II inhibitors for pain management in laparoscopic nissen fundoplication

BACKGROUND

This randomized, double-blind, prospective, placebo controlled study was planned to determine the effectiveness of selective COX-II inhibitors used preoperatively to alleviate pain after Nissen fundoplication surgery.

METHODS

For this study, 60 patients were allocated to four groups at random: group C (celecoxib, 200 mg by mouth), group R (rofecoxib, 50 mg by mouth), group P (placebo, pill), or group D (diclophenac sodium, 75 mg intramuscularly). Postoperative abdominal and shoulder pain experienced by the patient at rest, with motion, and with coughing were assessed. Side effects and postoperative analgesic requirement (tramadol, intramuscular) also were recorded.

RESULTS

The median tramadol requirement in the 1st h and total tramadol requirement at the 24th h were higher in group P than in the other study groups (p < 0.01). The pain scores in the first postoperative hour were higher in group P (p < 0.05).

CONCLUSIONS

The preoperative use of celecoxib, rofecoxib, or diclophenac in laparoscopic Nissen fundoplication surgery decreases pain intensity and tramadol requirement in the first postoperative hour and has a trarnadol sparing effect in the first 24 h.

Pain management in the wilderness and operational setting

The wilderness and operational setting places unique constraints on one's ability to treat pain. In this article we will discuss methods for treating pain both in the wilderness and operational setting. By operational we mean the austere deployed military setting, to include both noncombat and combat operations. The authors combined experience with wartime trauma pain management consists of experience in Operation "Just Cause" (Panama Invasion), Operation "Desert Storm" (Persian Gulf War), Operation "Uphold Democracy" (Haiti liberation), Operation "Enduring Freedom" (Afghanistan conflict), and Operation "Iraqi Freedom" (Iraq conflict).

A randomized crossover trial of tenoxicam compared with rofecoxib for postoperative dental pain control

Two non-steroidal anti-inflammatory drugs, tenoxicam and rofecoxib, were compared for the control of postoperative pain following surgical extraction of bilaterally and symmetrically impacted wisdom teeth performed under intravenous sedation and local anaesthesia. Thirty-five young fit adult patients received each analgesic treatment for four days in a randomized, crossover design. The results suggest statistically better pain relief for the selective COX-2 inhibitor rofecoxib compared to tenoxicam, a traditional NSAID. There were side-effects with both treatments. Abdominal discomfort was significantly more common following rofecoxib compared to tenoxicam. Both analgesics were acceptable to most participants in the trial.

Multimodal Analgesia Techniques and Postoperative Rehabilitation

The concept of multimodal analgesia involves the use of different classes of analgesics and different sites of analgesic administration to provide superior dynamic pain relief with reduced analgesic-related side effects. Although multimodal analgesia techniques have assumed increasing importance in the management of perioperative pain, it has become increasingly apparent that postoperative outcome may not be improved. Nevertheless, the integration of multimodal analgesia techniques with a multimodal and multidisciplinary rehabilitation program may enhance recovery, reduce hospital stay, and facilitate early convalescence.

Impact of Acute Pain and Its Management for Thoracic Surgical Patients

Perioperative analgesia for thoracotomy has evolved in concert with increasing knowledge of the impact of pain on recovery, the origin of this pain, and new methods for treating it. Thoracic surgery is one of the few areas where there is more general agreement between surgeons and anesthesiologists as to the importance of aggressive pain management, often with an indwelling epidural catheter left in place until after thoracostomy tube removal. The reasons for this agreement is that it has become increasingly clear to both specialties that pain puts patients with decreased pulmonary reserve who undergo thoracotomy at greater risk for morbidity. Future studies need to examine drugs or drug combinations that can lead to further reductions in the often intense pain that patients receiving aggressive epidural analgesia still experience. Studies directed at finding interventions capable of reducing the rate of long-term postthoracotomy pain still need to be performed.

Selektive Zyklooxygenase-2-Inhibitoren zur postoperativen Schmerztherapie

Systemic administration of analgesics is still the most widely used method for postoperative pain therapy. In the concept of balanced or multimodal analgesia non-steroidal anti-inflammatory drugs (NSAIDs) play an important role besides opioids. Their analgesic effect is based on a diminished prostaglandin synthesis by inhibition of the cyclooxygenase (COX) enzyme in the arachidonic acid metabolism. The discovery of at least two COX isoenzymes led to the development of selective COX-2 inhibitors that were hypothesized to have an improved risk-benefit-ratio compared with conventional NSAIDs. In this context the analgesic efficacy and adverse effects of selective COX-2 inhibitors for postoperative pain therapy were evaluated by reviewing the pertinent literature.

Evidence, Mechanisms, and Clinical Implications of Central Hypersensitivity in Chronic Pain After Whiplash Injury

OBJECTIVES

To provide insights into the mechanisms underlying central hypersensitivity, review the evidence on central hypersensitivity in chronic pain after whiplash injury, highlight reflections on the clinical relevance of central hypersensitivity, and offer a perspective of treatment of central hypersensitivity.

METHODS

A review of animal and human studies focusing on the mechanisms of postinjury central sensitization, an analysis of psychophysical investigations on central hypersensitivity in patients with chronic pain after whiplash injury, and a review of possible treatment modalities.

RESULTS

Animal data show that tissue damage produces plasticity changes at different neuronal structures that are responsible for amplification of nociception and exaggerated pain responses. Some of these changes are potentially irreversible. There is consistent psychophysical evidence for hypersensitivity of the central nervous system to sensory stimulation in chronic pain after whiplash injury. Tissue damage, detected or not by the available diagnostic methods, is probably the main determinant of central hypersensitivity. Psychologic distress could contribute to central hypersensitivity via imbalance of supraspinal and descending modulatory mechanisms. Although specific treatment strategies are limited, they are largely unexplored.

IMPLICATIONS

Central hypersensitivity may explain exaggerated pain in the presence of minimal nociceptive input arising from minimally damaged tissues. This could account for pain and disability in the absence of objective signs of tissue damage in patients with whiplash. Central hypersensitivity may provide a common neurobiological framework for the integration of peripheral and supraspinal mechanisms in the pathophysiology of chronic pain after whiplash. Therapy studies are needed.

Effect of meloxicam and carprofen on renal function when administered to healthy dogs prior to anesthesia and painful stimulation

OBJECTIVE

To determine whether administration of the nonsteroidal anti-inflammatory drugs meloxicam or carprofen to healthy dogs that were subsequently anesthetized and subjected to painful electrical stimulation has adverse effects on renal function as measured by glomerular filtration rate (GFR) and evaluation of serum concentrations of urea and creatinine.

ANIMALS

6 male and 6 female healthy young-adult Beagles.

PROCEDURE

A study was conducted in accordance with a randomized crossover Latin-square design. One of 3 treatments (saline [0.9% NaCl] solution, 0.2 mg of meloxicam/kg, or 4.0 mg of carprofen/kg) was administered i.v. 1 hour before anesthesia was induced by use of drugs in accordance with a standard anesthetic protocol (butorphanol tartrate and acepromazine maleate as preanesthetic medications, ketamine hydrochloride and diazepam for induction, and maintenance with isoflurane). Anesthetized dogs were subjected to intermittent electrical stimulation for 30 minutes. Direct, mean arterial blood pressure; heart rate; and respiratory rate were monitored. End-tidal isoflurane concentration was maintained at 1.5 times the minimum alveolar concentration. The GFR, as measured by plasma clearance of 99mTc-diethylenetriaminepentaacetic acid, and serum concentrations of serum and creatinine were determined 24 hours after induction of anesthesia.

RESULTS

Neither meloxicam nor carprofen significantly affected GFR or serum concentrations of urea and creatinine, compared with values for the saline treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

When administered 1 hour before onset of anesthesia and painful electrical stimulation, meloxicam or carprofen did not cause clinically important alterations of renal function in young healthy dogs.

What is the role of NSAIDs in pre-emptive analgesia?

NSAIDs inhibit the cyclo-oxygenase enzymes, and decrease peripheral and central prostaglandin production. In addition to reducing the inflammation that accompanies tissue injury, decreasing prostaglandin production attenuates the response of the peripheral and central components of the nervous system to noxious stimuli. Such a reduction in the response to pain can reduce the peripheral and central sensitisation induced by noxious stimuli, and reduce the pain experienced in response to subsequent noxious stimuli. These properties would seem to make NSAIDs ideal drugs to use in a pre-emptive fashion, where analgesics are administered prior to a noxious stimulus, such as surgery, with the expectation that reduction in peripheral and central sensitisation will lead to a decrease of pain.However, the available perioperative trials of pre-emptive NSAID use have yielded modest or equivocal results, and these may be due, in part, to controversy associated with the definition of pre-emptive analgesia and how to conduct the corresponding clinical trials. Although NSAIDs may have a limited ability by themselves to induce a pre-emptive analgesic effect, the available trials suggest how the perioperative use of these drugs may be made more effective. It is expected that NSAIDs will play an increasing role in multimodal analgesia and pain relief in general.

Acetylsalicylic Acid, Diclofenac, and Lornoxicam, but Not Rofecoxib, Affect Platelet CD 62 Expression

Nonsteroidal antiinflammatory drugs are routinely administered in the perioperative period. Because of the absence of cyclooxygenase-2 in platelets, cyclooxygenase-2-selective drugs are thought not to cause platelet inhibition. Because platelets play an important role in the coagulation process, the absence of platelet function inhibition may lead to fewer bleeding complications after surgery. We studied the influence of aspirin, diclofenac, lornoxicam, and rofecoxib on arachidonic acid and collagen-induced CD 62 P (P selectin) expression by using flow cytometry. Blood from 68 volunteers was obtained before and 1, 3, and 12 h after the oral ingestion of 1 of the randomly assigned study medications. Aspirin, diclofenac, and lornoxicam had a significant effect on arachidonic acid and collagen-induced CD 62 P expression in platelets, whereas rofecoxib did not show this effect. We conclude that rofecoxib is safe to use perioperatively with respect to inhibition of platelet function.

IMPLICATIONS

We compared the effect of rofecoxib and three nonselective nonsteroidal antiinflammatory drugs on platelet function, measured by CD 62 P expression. Platelet function was not altered by rofecoxib, but it was inhibited by aspirin, diclofenac, and lornoxicam. Rofecoxib may be safer than classic NSAIDs with respect to platelet function during the perioperative period.

Anaesthesia, surgery, and challenges in postoperative recovery

Surgical injury can be followed by pain, nausea, vomiting and ileus, stress-induced catabolism, impaired pulmonary function, increased cardiac demands, and risk of thromboembolism. These problems can lead to complications, need for treatment in hospital, postoperative fatigue, and delayed convalescence. Development of safe and short-acting anaesthetics, improved pain relief by early intervention with multimodal analgesia, and stress reduction by regional anaesthetic techniques, beta-blockade, or glucocorticoids have provided important possibilities for enhanced recovery. When these techniques are combined with a change in perioperative care a pronounced enhancement of recovery and decrease in hospital stay can be achieved, even in major operations. The anaesthetist has an important role in facilitating early postoperative recovery by provision of minimally-invasive anaesthesia and pain relief, and by collaborating with surgeons, surgical nurses, and physiotherapists to reduce risk and pain.

Role of Paracetamol in Acute Pain Management

Paracetamol (acetaminophen) has been shown to be an effective analgesic for the treatment of moderate pain where it is chiefly indicated, as shown in placebo-controlled studies in the perioperative setting and other acute pain states. In addition, an opioid-sparing effect has been demonstrated. No clinically relevant adverse effects are usually apparent with recommended doses. Paracetamol is an effective component in 'multimodal analgesia' in combination with morphine, weak opioids and non-steroidal anti-inflammatory drugs. Although most studies involve the perioperative setting, similar results have been obtained in other acute pain states, such as acute musculoskeletal pain, migraine, etc. In conclusion, paracetamol has a favourable efficacy-tolerability profile and is therefore recommended as a basic, first-line analgesic in acute pain states and as a valuable component in multimodal analgesia.