Emerging Trends and New Approaches to Acute Pain Management

Pharmacodynamics and clinical efficacy of fentanyl iontophoretic transdermal system for post-operative pain in hospitalized patients

INTRODUCTION

The fentanyl iontophoretic transdermal system (ITS) is a patient-controlled transdermal system allowing needle-free administration of on-demand doses of Fentanyl of 40 µg over a 10-min period up to 80 doses or over a 24-h period. It is indicated in opioid naïve patients for the treatment of acute postoperative pain in the hospitalized patients for up to 72 h.

AREAS COVERED

It has been demonstrated to be effective and safe in randomized trials and to provide comparable analgesia versus morphine intravenous (i.v.) patient-controlled analgesia (PCA) with adverse events similar between groups.

EXPERT OPINION

Fentanyl ITS has shown high patient satisfaction rates, and was described by patients and investigators as easy and convenient to use. These properties make this technology interesting when considering perioperative pain management. In the present health care environment additional data are required to establish the cost-benefit ratio of this technology in optimizing patient's recovery from surgery.

The shortened infusion time of intravenous ibuprofen part 1: a multicenter, open-label, surveillance trial to evaluate safety and efficacy

PURPOSE

The main purpose of the study was to determine the safety profile and efficacy of intravenous ibuprofen administered over 5 to 10 minutes for the treatment of pain or fever in hospitalized patients. Current evidence supports the use of intravenous infusions of ibuprofen to control pain and reduce the opioid requirements associated with surgical pain. Current dosing guidelines recommend that the drug be administered over 30 minutes. However, a more rapid infusion might yield additional benefits. The safety profile and efficacy of a shortened infusion time requires additional study.

METHODS

This was a Phase IV multicenter, open-label, surveillance clinical study. Thirteen clinical centers located in the United States enrolled a total of 150 adult hospitalized patients with pain or fever. Patients experiencing pain received 800 mg intravenous ibuprofen infused over 5 to 10 minutes every 6 hours for up to 24 hours (4 doses) and patients experiencing fever received 400 mg intravenous ibuprofen infused over 5 to 10 minutes every 4 hours for up to 24 hours (6 doses). Vital signs, adverse events, and pain scores were assessed. The exclusion criteria included inadequate intravenous access; patients younger than 18 years of age; history of allergy or hypersensitivity to any component of intravenous ibuprofen, aspirin, or other nonsteroid anti-inflammatory drugs; active hemorrhage or clinically significant bleeding; pregnancy or nursing; and patients in the perioperative period in the setting of coronary artery bypass graft surgery.

FINDINGS

Adverse events were reported for 43 of 150 patients (29%). The most common adverse events experienced by patients were infusion site pain in 22 of 150 patients (15%) and flatulence (8 of 150 [5%]). Four patients (3%) discontinued the study drug due to infusion-site pain. In the patients experiencing fever, temperature decreased from baseline over 4 hours (mean [SD] reduction of 1.5 [1.25]°F). In patients experiencing pain, patient-reported visual analog scale scores decreased from baseline over 4 hours (mean [SD] reduction of 27.1 [31.29] mm).

IMPLICATIONS

The study demonstrates that more rapid administration of intravenous ibuprofen is well tolerated and supports intravenous ibuprofen as an effective treatment for pain and fever in hospitalized patients.

Changes in the Bispectral Index in Response to Experimental Noxious Stimuli in Adults under General Anesthesia

Objective. Pain assessment is a major challenge in nonverbal patients in the intensive care unit (ICU). Recent studies suggest a relationship between the Bispectral Index (BIS) and nociceptive stimuli. This study was designed to examine changes in BIS in response to experimental noxious stimuli. Methods. Thirty participants under general anesthesia were in this quasiexperimental, within subject, pre- and poststudy. In the operating room (OR), BIS was monitored during moderate and severe noxious stimuli, induced by a thermal probe on the participants' forearm, after induction of general anesthesia, prior to surgery. Results. Significant increases in BIS occurred during moderate (increase from 35.00 to 40.00, P = 0.003) and severe noxious stimuli (increase from 37.67 to 40.00, P = 0.007). ROC showed a sensitivity (Se) of 40.0% and a specificity (Sp) of 73.3% at a BIS value > 45, in distinguishing a moderate from a severe noxious stimuli. Conclusion. BIS increased in response to moderate and severe noxious stimuli. The Se and Sp of the BIS did not support the use of the BIS for distinction of different pain intensities in the context of deep sedation in the OR. However, the results justify further studies in more lightly sedated patients such as those in the ICU.

Treating acute pain in the hospitalized patient

Many hospitalized patients report moderate-to-severe pain despite the use of epidural or patient-controlled analgesia. This article will explore the use of multimodal options for analgesia in hospitalized patients and focus on a difficult-to-treat acute pain condition, abdominal pain.

Pain management in critically ill obese patients

Achieving pain control in critically ill patients is a challenging problem for the health care team, which becomes more challenging in morbidly obese patients. Obese patients may experience drug malabsorption and distribution, which may lead to either subtherapeutic or toxic drug levels. To manage pain effectively for the critically ill obese patient, nurses must have an understanding of how obesity alters a patient's physiologic response to injury and illness. In addition, nurses must be knowledgeable about physiologic pain mechanisms, types and manifestations of pain, differing patterns of drug absorption and distribution, pharmacokinetic properties of analgesic medications, and pain management strategies. This article explores factors affecting pharmacokinetics in obese patients, trends in pain management, and treatment strategies for the obese patient.

Peripheral antinociceptive effects of the cyclic endomorphin-1 analog c[YpwFG] in a mouse visceral pain model

We previously described a novel cyclic endomorphin-1 analog c[Tyr-D-Pro-D-Trp-Phe-Gly] (c[YpwFG]), acting as a mu-opioid receptor (MOR) agonist. This study reports that c[YpwFG] is more lipophilic and resistant to enzymatic hydrolysis than endomorphin-1 and produces preemptive antinociception in a mouse visceral pain model when injected intraperitoneally (i.p.) or subcutaneously (s.c.) before 0.6% acetic acid, employed to evoke abdominal writhing (i.p. ED(50)=1.24 mg/kg; s.c. ED(50)=2.13 mg/kg). This effect is reversed by the selective MOR antagonist β-funaltrexamine and by a high dose of the mu(1)-opioid receptor-selective antagonist naloxonazine. Conversely, the kappa-opioid receptor antagonist nor-binaltorphimine and the delta-opioid receptor antagonist naltrindole are ineffective. c[YpwFG] produces antinociception when injected i.p. after acetic acid (ED(50)=4.80 mg/kg), and only at a dose of 20mg/kg did it elicit a moderate antinociceptive response in the mouse, evaluated by the tail flick assay. Administration of a lower dose of c[YpwFG] (10mg/kg i.p.) apparently produces a considerable part of antinociception on acetic acid-induced writhes through peripheral opioid receptors as this action is fully prevented by i.p. naloxone methiodide, which does not readily cross the blood-brain barrier; whereas this opioid antagonist injected intracerebroventricularly (i.c.v.) is not effective. Antinociception produced by a higher dose of c[YpwFG] (20mg/kg i.p.) is partially reversed by naloxone methiodide i.c.v. administered. Thus, only at the dose of 20mg/kg c[YpwFG] can produce antinociception through both peripheral and central opioid receptors. In conclusion, c[YpwFG] displays sufficient metabolic stability to be effective after peripheral administration and demonstrates the therapeutic potential of endomorphin derivatives as novel analgesic agents to control visceral pain.

The preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy in pediatric patients

BACKGROUND

Both ketorolac and propacetamol are used postoperatively to control mild to moderate pain. This study compared the analgesic efficacy of ketorolac and propacetamol delivered either preoperatively or postoperatively, and assessed the preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy.

METHODS

One hundred and two pediatric patients were divided randomly into four groups. The K1 and P1 groups received ketorolac 1 mg/kg or propacetamol 30 mg/kg after induction, respectively, whereas the K2 and P2 groups received each drug at the end of the operation, respectively. After adenotonsillectomy, we measured the NRS (Numerical Rating Scale), FPS (Faces Pain Scale) and OPS (Objective Pain scale) at 15, 30 and 60 min after arriving at the postanesthesia care unit.

RESULTS

There were no significant differences in the NRS, FPS and OPS between K1 and K2 and between P1 and P2 for 60 min after operation at the postanesthesia care unit.

CONCLUSIONS

These results suggest that both ketorolac (1 mg/kg) and propacetamol (30 mg/kg) have no preemptive analgesic effects during 1 hour after adenotonsillectomy.