Current treatment options for acute pain

Acute Pain Management

Acute pain management is improving steadily over the past few years, but training and professional education are still lacking in many professions. Untreated or undertreated acute pain could have detrimental effects on the patient in terms of comfort and recovery from trauma or surgery. Acute undertreated pain can decrease a patient's vascular perfusion, increase oxygen demand, suppress the immune system, and possibly risk increased incidence of venous thrombosis. Although acute postoperative pain needs to be managed aggressively, patients are most vulnerable during this period for developing adverse effects, and therefore, patient assessment and careful drug therapy evaluation are necessary processes in therapeutic planning. Acute pain management requires careful and thorough initial assessment and follow-up reassessment in addition to frequent dosage adjustments, and managing analgesic induced side effects. Analgesic selection and dosing must be based on the patient's past and recent analgesic exposure. There is no single acute pain management regimen that is suitable for all patients. Analgesics must be tailored to the individual patient.

Retrospective analysis of high-dose intrathecal morphine for analgesia after pelvic surgery

BACKGROUND

The effectiveness of intrathecal opioids (ITOs) for postoperative analgesia has been limited by reduced opioid dosing because of opioid-related side effects, most importantly respiratory depression. To overcome these limitations, high-dose intrathecal morphine was combined with a continuous intravenous (IV) postoperative naloxone infusion. The aim of the present chart analysis was to investigate the safety and efficacy of high-dose ITOs combined with IV naloxone compared with IV opioid analgesia alone.

METHODS

A retrospective chart analysis was performed on 121 female patients requiring major pelvic surgery. Ninety-eight patients received a single injection of high-dose ITOs before administration of typical general anesthesia, followed by an IV naloxone infusion at 5 µg⁄kg⁄h started post-ITO and continued for 22 h postoperatively. Twenty-three patients were given IV morphine (IVM) for postoperative analgesia and served as a reference group. Postoperative pain relief, analgesic consumption and ability to ambulate were assessed for 48 h postoperatively. Treatment safety was assessed by monitoring opioid-related side effects and vital signs. Data are presented as mean ± SD.

RESULTS

Mean ITOs given were morphine 1.1±0.2 mg combined with fentanyl 49 ± 6 µg. The mean worst pain visual analogue scale score in the first 12 h postoperatively was 0.2 ± 0.90 in the ITO group versus 4.3 ± 3.0 in the IVM group (P<0.05). On postoperative day 2, the mean worst pain visual analogue scale score was only 1 ± 1.8 in the ITO group versus 4.1 ± 2.6 in the IVM group (P<0.05). Analgesic requirements were reduced in the ITO group. In the first 24 h, the ITO group used 6.8±10.2 morphine equivalents (mg IV) versus 76.1 ± 44.4 in the IVM group (P<0.05). All patients in the ITO group were able to ambulate in the first 12 h postoperatively compared with 17⁄23 in the IVM group. There was a higher incidence of opioid-related sedation in the IVM group. Other opioid-related side effects were infrequent and minor in both groups.

CONCLUSIONS

High-dose ITOs combined with a postoperative IV naloxone infusion provided excellent analgesia for major pelvic surgery. The IV naloxone infusion combined with high-dose ITOs appeared to control opioid side effects without affecting analgesia.

Intraoperative Sensorcaine Significantly Improves Postoperative Pain Management in Outpatient Reduction Mammaplasty

BACKGROUND

Breast reduction is one of the most frequently performed plastic surgical procedures in the United States; more than 160,500 patients underwent the procedure in 2005. Many outpatient reduction mammaplasty patients report the greatest postoperative discomfort in the first 48 hours. The authors' investigated the effect of intraoperative topical application of the long-acting local anesthetic agent bupivacaine (Sensorcaine or Marcaine) on postoperative pain, time to postanesthesia care unit discharge, and postoperative use of narcotic medication.

METHODS

In a prospective, randomized, single-blind trial, intraoperative use of Sensorcaine versus placebo (normal saline) was compared. Postoperative pain was quantified using the visual analogue scale, and time to discharge from the postanesthesia care unit was recorded. Patients documented their outpatient pain medication usage.

RESULTS

Of the 37 patients enrolled in the study, 20 were treated with intraoperative topical Sensorcaine and 17 received placebo. Patients treated with Sensorcaine were discharged home significantly faster (2.9 hours versus 3.8 hours, p = 0.002). The control arm consistently had higher pain scores in the postanesthesia care unit (although not statistically significant) than the Sensorcaine group using the visual analogue scale system. Furthermore, patients receiving Sensorcaine required significantly less narcotic medication while recovering at home (mean, 3.5 tablets of Vicodin) than the control group (mean, 6.4 tablets; p = 0.001). There were no complications resulting from Sensorcaine usage.

CONCLUSIONS

This prospective, randomized, single-blind study demonstrates that a single dose of intraoperative Sensorcaine provides a safe, inexpensive, and efficacious way to significantly shorten the length of postanesthesia care unit stay and significantly decrease postoperative opioid analgesic use in patients undergoing ambulatory reduction mammaplasty.

The importance of ‘awareness’ for understanding fetal pain

Our understanding of when the fetus can experience pain has been largely shaped by neuroanatomy. However, completion of the cortical nociceptive connections just after mid-gestation is only one part of the story. In addition to critically reviewing evidence for whether the fetus is ever awake or aware, and thus able to truly experience pain, we examine the role of endogenous neuro-inhibitors, such as adenosine and pregnanolone, produced within the feto-placental unit that contribute to fetal sleep states, and thus mediate suppression of fetal awareness. The uncritical view that the nature of presumed fetal pain perception can be assessed by reference to the prematurely born infant is challenged. Rigorously controlled studies of invasive procedures and analgesia in the fetus are required to clarify the impact of fetal nociception on postnatal pain sensitivity and neural development, and the potential benefits or harm of using analgesia in this unique setting.

Intravenous Ketoprofen in Postoperative Pain Treatment after Major Abdominal Surgery

In recent years considerable attention has been paid to the treatment of postoperative pain, with regard to the favorable effect of adequate analgesia on patient outcome. Multimodal analgesia (e.g., opioids and nonsteroidal anti-inflammatory drugs [NSAIDs] or local anesthetics) is recommended for effective postoperative pain relief. There are few data on the use of NSAIDs in postoperative pain treatment after abdominal surgery. We conducted a randomized, double-blind, placebo-controlled study to assess the analgesic efficacy and safety of ketoprofen after major abdominal surgery. One and nine hours postoperatively patients received 100 mg of ketoprofen i.v. (n = 21) or placebo (n = 22) in addition to a pain-treatment protocol consisting of continuous infusion of tramadol 200 mg and metamizol 5 g over 24 hours with additional 25 mg i.v. tramadol in case of inadequate analgesia. Pain was assessed by numeric rating scale at rest and at deep breath 3, 6, 12, and 24 hours postoperatively and the total dose of tramadol used in the first 24 hours was recorded. Patients in the ketoprofen group had significantly lower pain scores both at rest and at deep breath, at 3 (p < 0.01), 6, and 12 hours (p < 0.05) postoperatively. The 24-hour use of tramadol was significantly lower in the ketoprofen group (p < 0.01), with less nausea and vomiting. There were no bleeding complications or other adverse events related to ketoprofen therapy. The study showed the value of short-term use of ketoprofen to improve the quality of analgesia after major abdominal surgery without significant adverse effects.

A randomized controlled study comparing rofecoxib, diclofenac sodium, and placebo in post-bunionectomy pain

OBJECTIVE

The relative efficacy of rofecoxib, diclofenac sodium, and placebo were compared in the treatment of acute pain after bunionectomy surgery.

RESEARCH DESIGN AND METHODS

This was a double-blind, randomized, two-part study of 252 patients with moderate-to-severe pain the day after first metatarsal bunionectomy. Patients were treated with a single dose of rofecoxib 50 mg (N = 85), enteric-coated diclofenac sodium 100 mg (N = 85), or placebo (N = 82) on study Day 1 (Part I), and subsequently with daily rofecoxib 50 mg or placebo (diclofenac patients switched to placebo) over study Days 2-5 (Part II). Patients rated their pain at 16 time points over the first 24 h. Primary endpoint was total pain relief over 8 h (TOPAR8). Pre-specified secondary endpoints on Day 1 included onset of analgesia, peak pain relief, and duration of response. For Part II, supplemental analgesia use with rofecoxib compared to placebo was pre-specified for analysis over Days 2-5, with the focus on Days 2-3. Adverse experiences were recorded over Days 1-5.

RESULTS

For TOPAR8 scores, rofecoxib 50 mg was significantly more effective than placebo (9.5 vs. 3.7, p < 0.001) and diclofenac (9.5 vs. 5.0, p < 0.001). Onset of analgesia was more rapid with rofecoxib than placebo (p = 0.003) and diclofenac (p = 0.019); proportion of patients achieving onset within 4 h with rofecoxib, diclofenac, and placebo was 46%, 27%, and 23%, respectively. Peak pain relief was greater with rofecoxib (1.8) than diclofenac (1.2, p = 0.004) and placebo (1.0, p < 0.001). Diclofenac and placebo patients required supplemental analgesia sooner than rofecoxib patients (2:03 h vs. 4:02 h, p < 0.001 and 1:41 h vs. 4:02 h, p < 0.001). Rofecoxib patients used significantly less (p < 0.001) supplemental analgesia than placebo patients over Days 2-3 (1.1 tablets/day vs. 2.1 tablets/day) and Days 2-5 (0.9 tablets/day vs. 1.8 tablets/day). No significant differences in adverse experiences between treatments were seen.

CONCLUSION

Rofecoxib 50 mg was significantly more effective than placebo on all measures of treatment of post-bunionectomy pain. Rofecoxib 50 mg was significantly more effective than diclofenac sodium 100 mg based on Day 1 endpoints of total pain relief, onset time, and duration of response. All study medications were generally well tolerated.

The synthesis and pharmacological evaluation of (±)-2, 3- seco-fentanyl analogues

An efficient, five-step synthetic approach to various acyclic 1,3-diamines has been developed and applied to the preparation of a novel class of open-chained fentanyl analogues. The acyclic derivatives 5.1?5.5 (all new compounds) were synthesized with the aim of estimating the significance of the piperidine ring for the opioid analgesic activity of anilido-piperidines. The starting ?-keto-amide 1.1, prepared by the aminolysis of methyl acetoacetate with methylphenethylamine, (93 % yield), was successively reacted with NaH and BuLi, to form the highly reactive ?,?-dienolate anion 1.1a. Regio and chemoselective ?-alkylation of the dienolate with various primary and secondary alkyl halides furnished the ?-keto-amides 1.2?1.5 (76?91 %). Reductive amination of the keto-amides 1.1?1.5 with aniline and Zn powder in acetic acid, via the enamine intermediates 2.1?2.5, afforded the ?-anilino amides 3.1?3.5 (74?85 %). After reductive deoxygenation of the tertiary amide group, using in situ generated diborane, the corresponding 1,3-diamines 4.1?4.5 were obtained (87?97 %). The synthesis of (?)-2,3-seco-fentanyls 5.1?5.5 was completed by N-acylation of the diamines 4.1?4.5 with propionyl chloride, followed by precipitation of the monooxalate salts (86?95 %). The parent compound, 2,3-seco-fentanyl 5.1, was found to be a 40 times less potent narcotic analgesic than fentanyl but still 5?6 times more active than morphine in rats, while i-Pr derivative 5.3 was inactive. Apart from the pharmacological significance, the general procedure described herein may afford various functionalized, 1,3-diamines as potential complexing agents and building blocks for the synthesis of aza-crown ethers.