Comparison of analgesic effect between gabapentin and diclofenac on post-operative pain in patients undergoing tonsillectomy

Comparing the effects of pre-emptive oxycodone, diclofenac, and gabapentin on postoperative pain after tibia fracture surgery: A randomized clinical trail

Background

Postoperative pain (POP) is one of the most common and most important types of pain.

Objectives

The aim of this study was to compare the effects of pre-emptive oxycodone, diclofenac, and gabapentin on postoperative pain (POP) among patients with tibia fracture surgery.

Materials and Methods

This double-blind three-group randomised controlled trial was conducted in 2023. Participants were 111 candidates for tibia fracture surgery under general anaesthesia. They were randomly allocated to oxycodone, gabapentin, and diclofenac groups through block randomisation. Baseline arterial oxygen saturation, heart rate, and blood pressure were documented before surgery and POP and sedation status were measured during postoperative recovery and 2, 4, 6, 12, and 24 h after surgery. Postoperative opioid analgesic use was also documented. The data were analysed using the SPSS software (v. 20.0) at a significance level of less than 0.05.

Results

Groups did not significantly differ from each other respecting participants' baseline age, gender, body mass index, arterial oxygen saturation, heart rate, blood pressure, and surgery duration (P > 0.05). Moreover, there were no significant differences among the groups respecting POP and sedation status at different measurement time points (P > 0.05), except for six hours after surgery at which the POP mean score in the gabapentin group was significantly less than the other two groups (P = 0.001). Among-group differences respecting postoperative use of opioid analgesics and medication side effects were also insignificant (P > 0.05).

Conclusion

Pre-emptive oxycodone, diclofenac, and gabapentin significantly reduce POP among patients with tibia fracture surgery, though gabapentin may produce more significant analgesic effects. All these three medications can be used for pre-emptive analgesia. Of course, the best pre-emptive analgesic agent is determined based on the opinion of the treating physician.

Comparing the Effects of Pregabalin and Clonidine on Postoperative Pain in Tonsillectomy: A Randomized, Double-Blind, Prospective Clinical Trial

BACKGROUND

Tonsillectomy is one of the most common surgical procedures. This study compared the effect of Pregabalin and Clonidine on postoperative pain in adult patients undergoing elective tonsillectomy.

METHODS

This randomized, double-blind, prospective clinical trial was conducted among 92 patients aged 20 to 50. The clonidine group (C) was given 150 µg of clonidine tablet 90 minutes before surgery, and the pregabalin group (P) was given 300 mg of pregabalin tablet 90 minutes before surgery. The results were analyzed by SPSS 25, and statistical analysis consisted of chisquare, T-test, and χ2 tests, and a p-value less than 0.05 was considered significant.

RESULTS

The mean pain score and analgesic consumption scores in the pregabalin group were lower than in the clonidine group. According to the t-test, there was a significant difference between the two groups regarding pain score and analgesic consumption (p <0.05). Hemodynamic variation in both groups had no significant differences (p >0.05).

CONCLUSION

The present study showed that pregabalin reduced postoperative pain and analgesic consumption more effectively than clonidine.

The Effect of Pre-Emptive Analgesia on the Postoperative Pain in Pediatric Otolaryngology: A Randomized, Controlled Trial

The aim of this randomized, controlled trial was to determine whether children undergoing otolaryngological procedures (adenoidectomy, adenotonsillotomy, or tonsillectomy) benefit from pre-emptive analgesia in the postoperative period. Methods: Fifty-five children were assessed for eligibility for the research. Four children refused to participate during the first stage of the study, leaving fifty-one (n = 51) to be randomly assigned either to receive pre-emptive analgesic acetaminophen (15 mg/kg; n = 26) or a placebo (n = 25) in addition to midazolam (0.5 mg/kg) as premedication. All children were anesthetized with sevoflurane, propofol (2−4 mg/kg), and fentanyl (2 mcg/kg). Postoperative pain was assessed using the Visual Analogue Scale (VAS), the Wong−Baker Faces Pain Rating Scale, and the Face, Legs, Activity, Cry, and Consolability (FLACC) scale. The postoperative pain was measured 1, 2, 4, and 6 h after the surgery. Results: The clinical trial reported a statistically significant correlation between administering pre-emptive analgesia (acetaminophen) and reducing pain in children after otolaryngological procedures compared to placebo. The ratio of boys to girls and age were similar among the groups (p > 0.05), so the groups of children were not divided by gender or age. Conclusions: Standard pre-emptive analgesia reduced the severity of pain in the postoperative period after otolaryngological procedures in children. Acetaminophen given before surgery reduces postoperative pain in children undergoing otolaryngological procedures.

Pharmacologic management of post-tonsillectomy pain in children

Tonsillectomy is a very common procedure in children, often performed on an outpatient basis. Severe postoperative pain is common, and can be prolonged. Despite a large number of available analgesic medications, often employed in combination, achieving adequate pain control remains a persistent challenge. Research suggests a tendency among caregivers to undertreat pain, and a need for detailed care instructions and education to ensure adequate pain management. Furthermore, ongoing questions regarding the safety and efficacy of the most commonly used medications have led to wide variance in practice patterns and continuous reassessment through research that yields sometimes conflicting results. This review summarizes the current state of the literature and presents a management approach which attempts to maximize pain control while minimizing potential harm with combinations of medications and modification based on patient-specific factors.

The Effects of Ondansetron on the Analgesic Action of Intravenous Acetaminophen after Tonsillectomy in Children: A Triple-Blind Randomized Controlled Trial

Introduction

Severe pain, nausea, and vomiting after tonsillectomy surgery are among the issues that not only affect patient satisfaction but also may result in complications and delay patient discharge. This study was conducted to assess the effect of intravenous administration of ondansetron on the analgesic action of intravenous acetaminophen after tonsillectomy in children. Materials and methods. This randomized controlled trial was conducted on 53 children between the age of 3 and 12 years old who were referred to Besat Hospital Hamadan, Iran, for tonsillectomy. Patients were randomly assigned to two groups. The intervention group (I) received intravenous acetaminophen plus 0.1 mg/kg ondansetron intravenously while the control group (C) received intravenous acetaminophen plus 2 ml of normal saline intravenously. Postoperative pain severity was assessed using the Children's Hospital Eastern Ontario Pain Scale (CHEOPS). Frequency of nausea, vomiting, and need for analgesic was assessed and recorded four times, at recovery unit, after 6, 12, and 24 hours postsurgery. Data analysis was performed at 95% confidence level using the statistical package for social sciences (SPSS) software version 21.

Results

The number of patients in groups I and C was 27 and 26 patients, respectively. Mean pain score in I and C groups was 4.48 and 2.88 at recovery unit, 2.74 and 2.04 after 6 hours, 1.67 and 0.81 after 12 hours, and 0.67 and 0.20 after 24 hours postsurgery, respectively. Frequency of nausea at recovery unit was 23.1% in I group and 0.0% in group C (p = 0.010) while the mean number of analgesic requirements in I and C groups was 1.07 and 0.56 times, respectively (p = 0.027).

Conclusions

Intravenous administration of 0.1 mg/kg ondansetron reduces the analgesic action of intravenous acetaminophen after tonsillectomy in 3 to 12-year-old children.

Effects of Gabapentin Suspension and Rectal Acetaminophen on Postoperative Pain of Adenotonsillectomy in Children

Introduction

Adenotonsillectomy is the main treatment for symptomatic tonsillar hypertrophy with postoperative pain as the most common associated complication. The present study aimed to compare the efficacy of gabapentin with that reported for acetaminophen on the postoperative pain of adenotonsillectomy in children.

Materials and Methods

In this double-blind clinical trial, a total of 60 children within the age range of 7-15 years undergoing adenotonsillectomy were randomly allocated to two groups of gabapentin (n=30) and acetaminophen (n=30). The first group received a 10 mg/kg dose of gabapentin suspension preoperatively and placebo (suppository) after the intubation. The second group received a 40 mg/kg dose of acetaminophen suppository and placebo suspension simultaneous with that in the case group. Using the pain scale (based on the score of visual analog scale, prescribed drugs, dosage as well as incidence of postoperative nausea and vomiting were recorded 0, 2, 4, 6, 12, and 24 h after the surgery. The data were analyzed using SPSS software (version 22.0). A p-value less than 0.05 was considered statistically significant.

Results

There was no significant difference between the two groups considering the pain scores at 0, 2, 4, 6, 12, and 24 h after the surgery. In addition, the trend of pain intensity statistically decreased within 0 to 24 h in both acetaminophen (P<0.001) and gabapentin (P<0.001) groups. No statistically significant difference was observed between the two groups regarding the postoperative incidence of nausea and vomiting.

Conclusion

The obtained results of the present study showed that the administration of gabapentin and acetaminophen significantly reduced the postoperative pain of tonsillectomy and need for narcotics in these patients after the surgery. However, in this study, there was no particular reported superiority for any of the two groups in terms of the effects of gabapentin suspension and rectal acetaminophen.

Effects of Gabapentinoids Premedication on Shoulder Pain and Rehabilitation Quality after Laparoscopic Cholecystectomy: Pregabalin versus Gabapentin

Introduction

Gabapentinoids are increasingly used in preoperative premedication despite controversial results. The aim of our study was to evaluate the effects of preemptive use of gabapentin or pregabalin on postoperative shoulder pain and rehabilitation quality after laparoscopic cholecystectomy.

Methods

This is a clinical trial comparing the effects of a preoperative premedication with 600 mg of gabapentin or 150 mg of pregabalin versus placebo on postoperative pain and recovery quality after laparoscopic cholecystectomy. Premedication was taken 2 hours before the surgery beginning. Ninety patients were included and randomized into 3 groups (gabapentin, pregabalin, and placebo). The anesthetic protocol was the same for all patients. Primary endpoint was the shoulder pain intensity at the 48th postoperative hour. Secondary endpoints were postoperative nausea and vomiting (PONV), sleep quality during the first night, and the onset time for the first standing position.

Results

During the first 48 postoperative hours, the gabapentin and pregabalin groups had significantly lower shoulder pain than the placebo group (p < 0.05). In gabapentinoids groups, the incidence of PONV was lower and the sleep quality during the first postoperative night was better with significant results. Mean Spiegel scores were 22.43 ± 1.45, 22.30 ± 1.44, and 17.17 ± 1.66, respectively, in pregabalin, gabapentin, and placebo groups (p < 0.05). The delay for the first standing position was 14.9 ± 4.9 hours in the pregabalin group, 9.7 ± 3.6 hours in the gabapentin group, and 21.6 ± 2.1 hours in the placebo group. No superiority was found between gabapentin and pregabalin.

Conclusion

Preemptive premedication with gabapentinoids can enhance postoperative rehabilitation quality after laparoscopic cholecystectomy by reducing postoperative shoulder pain, decreasing PONV incidence, and improving sleep quality during the first postoperative night. This trial is registered with ClinicalTrial.gov (NCT03241875).

Gabapentin in the Management of Pain following Tonsillectomy: A Randomized Double-Blind Placebo-Controlled Trial

Objective To determine if a single dose of oral gabapentin given prior to tonsillectomy decreases postoperative morbidity. Study Design Prospective randomized double-blind placebo-controlled trial. Setting Southern District Health Board University Hospitals, New Zealand, over a 10-month period. Subjects and Methods Seventy-three adults undergoing tonsillectomy were randomized to receive either a single preoperative dose of oral gabapentin (600 mg) or placebo. A standard analgesic protocol was prescribed for 14 postoperative days. The primary outcome was a patient-assigned visual analog scale pain score during rest and swallow; secondary outcomes were analgesic consumption, nausea, vomiting, and return to normal diet and activities. Complications and adverse effects were also recorded. Results Thirty-seven participants were allocated to the placebo group and 36 to the gabapentin group. After withdrawals, data were analyzed from 31 in the placebo group and 27 in the gabapentin group. Pain scores between groups were not significantly different within the first 6 hours. The gabapentin group recorded significantly higher pain scores between days 5 and 10 (maximal difference, day 8: 17.6 mm; effect size, -8.87; P = .03; 95% CI, -16.883 to -0.865). There was no significant difference in swallow pain scores or early postoperative fentanyl consumption. Consumption of paracetamol ( P = .01 at day 13 and P = .004 at day 14) and codeine ( P < .05 at days 3-5, 7, 8, 10, 14) was higher in the gabapentin group. No significant difference between groups was found for the other outcomes. Conclusions Preemptive gabapentin (600 mg) was associated with greater postoperative pain scores and analgesic consumption following adult tonsillectomy when compared with placebo.

Hypoxic Stress and Inflammatory Pain Disrupt Blood-Brain Barrier Tight Junctions: Implications for Drug Delivery to the Central Nervous System

A functional blood-brain barrier (BBB) is necessary to maintain central nervous system (CNS) homeostasis. Many diseases affecting the CNS, however, alter the functional integrity of the BBB. It has been shown that various diseases and physiological stressors can impact the BBB's ability to selectively restrict passage of substances from the blood to the brain. Modifications of the BBB's permeability properties can potentially contribute to the pathophysiology of CNS diseases and result in altered brain delivery of therapeutic agents. Hypoxia and/or inflammation are central components of a number of diseases affecting the CNS. A number of studies indicate hypoxia or inflammatory pain increase BBB paracellular permeability, induce changes in the expression and/or localization of tight junction proteins, and affect CNS drug uptake. In this review, we look at what is currently known with regard to BBB disruption following a hypoxic or inflammatory insult in vivo. Potential mechanisms involved in altering tight junction components at the BBB are also discussed. A more detailed understanding of the mediators involved in changing BBB functional integrity in response to hypoxia or inflammatory pain could potentially lead to new treatments for CNS diseases with hypoxic or inflammatory components. Additionally, greater insight into the mechanisms involved in TJ rearrangement at the BBB may lead to novel strategies to pharmacologically increase delivery of drugs to the CNS.

Effects of pregabalin and gabapentin on postoperative pain and opioid consumption after laparoscopic cholecystectomy

Background

Gabapentin and pregabalin are antiepileptic drugs that are also used for chronic pain treatment. This study evaluated the effects of pregabalin and gabapentin on postoperative pain in patients undergoing laparoscopic cholecystectomy.

Methods

A total of 108 candidates for elective laparoscopic cholecystectomy were randomly assigned to gabapentin (n = 36), pregabalin (n = 36), and placebo (n = 36) groups. Patients received 800 mg of gabapentin or 150 mg of pregabalin orally one hour before surgery. Postoperative analgesia was administered by pethidine via patient-controlled analgesia. The amount of opioid consumed, number of nausea events, vomiting, and pain scores at 2, 6, 12, and 24 hours after surgery were recorded.

Results

The gabapentin and pregabalin groups had significantly lower pain intensity than the placebo group, and pain intensity in the pregabalin group decreased more compared to the gabapentin group. The mean amount of pethidine consumption in the placebo group was significantly higher than in the gabapentin and pregabalin groups.

Conclusions

A single dose of gabapentin or pregabalin decreased postoperative pain and nausea, as well as vomiting and opioid consumption after laparoscopic cholecystectomy. Moreover, the findings revealed that pregabalin was superior to gabapentin for reducing postoperative pain.

Gabapentin for Perioperative Analgesia in Otorhinolaryngology-Head and Neck Surgery: Systematic Review

OBJECTIVE

Recent research has investigated the role of gabapentin in perioperative pain relief in otorhinolaryngology-head and neck surgery. This review aims to identify whether sufficient evidence exists for the routine use of gabapentin in the perioperative setting.

DATA SOURCES

MEDLINE, Cochrane CENTRAL, EMBASE, and Google Scholar.

REVIEW METHODS

A comprehensive systematic search was performed with keywords for articles up to November 2015. The systematic review included all randomized, placebo-, and active-controlled trials investigating the role of perioperative gabapentin for pain in otorhinolaryngology-head and neck surgery. The studies were assessed for risk of bias and selected and reviewed by the main author. Selected trials were required to have data in the form of pain intensity scores, analgesic consumption, adverse effects, or return to normal function.

RESULTS

A total of 14 randomized controlled trials were included, of which 4 had an active control. The placebo-controlled trials included 4 for tonsillectomy, 3 for rhinology, and 3 for thyroidectomy. These studies were not suitable for meta-analysis. Trial quality involving gabapentin in tonsillectomy surgery is variable. The higher-quality studies reported significantly reduced analgesic consumption in the gabapentin groups, with the effect on pain scores less clear. There was a significant benefit, within the first 24 hours, in pain and analgesic consumption as compared with placebo favoring the gabapentin groups following rhinologic and thyroid surgery.

CONCLUSION

Overall, gabapentin appears to have a significant beneficial effect on perioperative pain relief and analgesic consumption in otorhinolaryngology-head and neck surgery procedures within the first 24 hours.

The Effect of Administration of Ketamine and Paracetamol Versus Paracetamol Singly on Postoperative Pain, Nausea and Vomiting After Pediatric Adenotonsillectomy

BACKGROUND

Tonsillectomy is one of the most common surgeries in children and posttonsillectomy pain and agitation management is a great challenge for anesthesiologists.

OBJECTIVES

The aim of this study was to compare the efficacy of a single dose of ketamine combined with paracetamol with paracetamol alone in the management of postoperative pain in tonsillectomy.

MATERIALS AND METHODS

In this study, the subjects were randomly allocated into the two groups: the ketamine and control. Intravenous paracetamol infusion (15 mg/kg) was started 15 minutes before the end of surgery in both groups, continued with the IV injection of ketamine (0.25 mg/kg) in the ketamine group and an equal volume of saline in the control group. Using the children's hospital of eastern Ontario (CHEOPS) pain scale, pain and agitation score and also the incidence of nausea and vomiting after the surgery were recorded in 0.5, 6 and 12 hours after the operation. Data were analyzed using SPSS software version 16 and P value less than 0.05 was considered as statistically significant in all cases.

RESULTS

There was no significant difference between the two groups considering demographic data (age, sex distribution, weight and height). The CHEOPS pain scales were significantly lower in the ketamine group compared to the control group at 0.5 and 6 hours after the surgery (P = 0.003 and P = 0.023, respectively). There was no significant difference in the CHEOPS scale at 12 hours after the surgery, dose of adjuvant analgesic and the incidence of nausea and vomiting after the surgery between the two groups.

CONCLUSIONS

According to the results of the current study, postoperative analgesia in children was improved in the ketamine group. Therefore, for better management of posttonsillectomy pain, low-dose ketamine administration with paracetamol is recommended.

Post-tonsillectomy pain control: consensus or controversy?

Pediatric post-tonsillectomy analgesia continues to be highly debated and an area of active research. Tonsillectomy pain can lead to significant patient morbidity, and incur potentially avoidable healthcare costs. Moreover, the various analgesic classes, each present their own risk profiles and unique side effects when used in children post-tonsillectomy. This review delineates the clinical and pathophysiological basis for post-tonsillectomy pain, types of analgesics and their risk profiles, as well as special considerations in this clinical population and a review of alternative analgesic treatment options. This article presents a summary of recent literature and discusses evidence-based management options to aid medical and allied health professionals who may encounter these patients.

The efficacy of gabapentin/pregabalin in improving pain after tonsillectomy: A meta-analysis

OBJECTIVES/HYPOTHESIS

Gabapentin and pregabalin are useful for treating neuropathic pain because of their antiallodynic and antihyperalgesic properties, which may be beneficial in managing acute postoperative pain. The goal of this meta-analysis was to perform a systematic review of the literature on the effect of gabapentinoids on postoperative pain following tonsillectomy, and its adverse effects in patients.

DATA SOURCES

MEDLINE, SCOPUS, and Cochrane database.

METHODS

Two authors independently searched the databases from their inception of article collection to May 2015. Included in the analysis were studies that compared preoperative gabapentinoid administration (gabapentinoids groups) with a placebo or pain control agent (control group) during a 24-hour postoperative period, the outcomes of interest being postoperative pain intensity; rescue analgesic consumption; or adverse effects such as sedation, nausea and vomiting, dizziness, and headache.

RESULTS

The pain score reported by the physician during the first 8 hours, as well as the need for analgesics during 24 hours postoperatively, were significantly decreased in the gabapentinoids group versus the control group. Additionally, there was no significant difference between gabapentinoids and control groups for adverse effect during 24 hours postoperatively. In the subgroup analyses (gabapentin and pregabalin) regarding pain-related measurements, two subgroups showed the similar effect on reducing the postoperative pain severity.

CONCLUSION

Preoperative administration of gabapentinoids could provide pain relief without side effects in patients undergoing tonsillectomy. However, considering the insufficient evaluation of efficacy of gabapentinoids according to the high heterogeneity in some parameters, further clinical trials with robust research methodology should be conducted in order to confirm the results of this study.

LEVEL OF EVIDENCE

NA.

Effects of Oral Gabapentin, Local Bupivacaine and Intravenous Pethidine on Post Tonsillectomy Pain

INTRODUCTION

Tonsillectomy is one of the most common surgeries performed worldwide. Post-operative pain arising from tonsillectomy is one of the earliest complications that can postpone oral nutrition and increase the hospitalization period. Administration of opioids via injection is usually preferred to relieve pain in these patients. However, the side effects of this approach prompted us to seek alternative treatments. In this study, the effectiveness of oral gabapentin is compared with an intravenous (IV) injection of pethidine and a local injection of bupivacaine in the control of pain after tonsillectomy.

MATERIALS AND METHODS

This clinical trial was performed on 7-15 year-old patients who were candidates for tonsillectomy at Shahrekord Kashani hospital from 2012-2013. The patients were divided into three groups at random. Group 1 was give 20 mg/kg oral gabapentin 1 hour before anesthesia. In Group 2, 2.5 ml bupivacaine 0.25% was injected into each tonsil bed by a surgeon. In Group 3,1 mg/kg pethidine was injected intravenously after intubation. To assess post-operative pain, the Oucher scale was used in recovery as well as 3,6,12, and 24 hours after surgery.

RESULTS

The pain score was lowest in the gabapentin group and highest in the bupivacaine group during the study. The pain score in the gabapentin group was significantly lower than that in the bupivacaine group (P<0.05). No statistically significant difference was found between the pain score of the Pethidine group and that of the Bupivacaine group (P>0.05).

CONCLUSION

Gabapentin, with its antihyperalgesic properties and other unknown properties, is a convenient drug for controlling pain following tonsillectomy.

Gabapentin's anti-nausea and anti-emetic effects: a review

Gabapentin's main clinical use is in the treatment of neuropathic pain where its binding to neuronal alpha-2/delta subunits of voltage-gated calcium channels (VGCCs) is critical to its mechanism of action. Over the past 10 years, there have been several reports of gabapentin also having anti-nausea and anti-emetic effects in conditions including postoperative nausea and vomiting (PONV), chemotherapy-induced nausea and vomiting (CINV), and hyperemesis gravidarum (HG). In this report, a MEDLINE electronic search was performed, and relevant citations were reviewed and classified by level of evidence; a grade of recommendation was then assigned for gabapentin's use for each studied indication. Out of 33 clinical trials reviewed, 12 assessed nausea and/or vomiting (N/V) associated with gabapentin therapy as primary outcome measures. These 12 studies provided a Grade A recommendation for gabapentin use in treating PONV, a Grade B recommendation for use in treating CINV, and a Grade C recommendation for use in treating HG. Further research is needed to confirm these initial promising results, which implicate the alpha-2/delta VGCC subunit as a novel therapeutic target in the treatment of several N/V-associated clinical conditions.

P-glycoprotein modulates morphine uptake into the CNS: a role for the non-steroidal anti-inflammatory drug diclofenac

Our laboratory has previously demonstrated that peripheral inflammatory pain (PIP), induced by subcutaneous plantar injection of λ-carrageenan, results in increased expression and activity of the ATP-dependent efflux transporter P-glycoprotein (P-gp) that is endogenously expressed at the blood-brain barrier (BBB). The result of increased P-gp functional expression was a significant reduction in CNS uptake of morphine and, subsequently, reduced morphine analgesic efficacy. A major concern in the treatment of acute pain/inflammation is the potential for drug-drug interactions resulting from P-gp induction by therapeutic agents co-administered with opioids. Such effects on P-gp activity can profoundly modulate CNS distribution of opioid analgesics and alter analgesic efficacy. In this study, we examined the ability of diclofenac, a non-steroidal anti-inflammatory drug (NSAID) that is commonly administered in conjunction with the opioids during pain therapy, to alter BBB transport of morphine via P-gp and whether such changes in P-gp morphine transport could alter morphine analgesic efficacy. Administration of diclofenac reduced paw edema and thermal hyperalgesia in rats subjected to PIP, which is consistent with the known mechanism of action of this NSAID. Western blot analysis demonstrated an increase in P-gp expression in rat brain microvessels not only following PIP induction but also after diclofenac treatment alone. Additionally, in situ brain perfusion studies showed that both PIP and diclofenac treatment alone increased P-gp efflux activity resulting in decreased morphine brain uptake. Critically, morphine analgesia was significantly reduced in animals pretreated with diclofenac (3 h), as compared to animals administered diclofenac and morphine concurrently. These novel findings suggest that administration of diclofenac and P-gp substrate opioids during pain pharmacotherapy may result in a clinically significant drug-drug interaction.