Mitchell P. Engle

Intrathecal oxytocin inhibits visceromotor reflex and spinal neuronal responses to noxious distention of the rat urinary bladder.

Background and Objectives Oxytocin (OXY) is a neuropeptide that has recently been recognized as an important component of descending analgesic systems. The present study sought to determine if OXY produces antinociception to noxious visceral stimulation. Methods Urethane-anesthetized female rats had intrathecal catheters placed acutely, and the effect of intrathecal OXY on visceromotor reflexes (VMRs; abdominal muscular contractions quantified using electromyograms) to urinary bladder distension (UBD; 10-60 mm Hg, 20 seconds; transurethral intravesical catheter) was determined. The effect of OXY applied to the surface of exposed spinal cord was determined in lumbosacral dorsal horn neurons excited by UBD using extracellular recordings. Results Oxytocin doses of 0.15 or 1.5 &mgr;g inhibited VMRs to UBD by 37% ± 8% and 68% ± 10%, respectively. Peak inhibition occurred within 30 minutes and was sustained for at least 60 minutes. The effect of OXY was both reversed and prevented by the intrathecal administration of an OXY-receptor antagonist. Application of 0.5 mM OXY to the dorsum of the spinal cord inhibited UBD-evoked action potentials by 76% ± 12%. Consistent with the VMR studies, peak inhibition occurred within 30 minutes and was sustained for greater than 60 minutes. Conclusions These results argue that intrathecal OXY produces an OXY receptor–specific antinociception to noxious UBD, with part of this effect due to inhibition of spinal dorsal horn neurons. To our knowledge, these studies provide the first evidence that intrathecal OXY may be an effective pharmacological treatment for visceral pain.

Compliance with Opioid Therapy: Distinguishing Clinical Characteristics and Demographics Among Patients with Cancer Pain

Background Because an increase of patients who misuse opioids has been identified in our cancer clinical setting through urine drug testing (UDT) and the Screener and Opioid Assessment for Patients with Pain-Short Form (SOAPP-SF), we conducted this retrospective cohort study to identify patient characteristics that are associated with UDT that indicates noncompliance. Methods Over a two-year period, 167 of 8,727 patients (2.4%) seen in the pain clinic and who underwent UDT were evaluated to determine compliance with prescribed opioid regimens. Descriptive clinical and demographic data were collected, and group differences based on compliance with opioid therapy were evaluated. Results Fifty-eight percent of the patients were noncompliant with their prescribed opioid therapy. Noncompliant patients were younger than compliant patients, with a median age of 46 vs 49 years (P = 0.0408). Noncompliant patients were more likely to have higher morphine equivalent daily doses; however, the difference was not statistically significant. Patients with a history of alcohol (ETOH) (P = 0.0332), illicit drug use (P = 0.1014), and smoking (P = 0.4184) were more likely noncompliant. Univariate regression analysis showed that a history of ETOH use (P = 0.034), a history of anxiety (P = 0.027), younger age (P = 0.07), and a SOAPP-SF score of 4 or higher (P = 0.05) were associated with an abnormal UDT. Conclusions History of ETOH use, anxiety, high SOAPP-SF score, and younger age were associated with UDT that indicates noncompliance. Given the very small percentage of UDT testing, it is quite likely that a significant number of patients who did not undergo UDT were also nonadherent with treatment recommendations.

Evidence-based pain medicine for primary care physicians

ABSTRACT The last several decades have seen a marked increase in both the recognition and treatment of chronic pain. Unfortunately, patients frequently misunderstand both the nature of pain and the best practices for its treatment. Because primary care physicians treat the majority of chronic pain, they are ideally situated to provide evidence-based pain care. The majority of the medical evidence supports a biopsychosocial model of pain that integrates physical, emotional, social, and cultural variables. The goal of this primer is to assist primary care physicians in their understanding of pain, evaluation of the chronic pain patient, and ability to direct evidence-based care. This article will discuss the role of physical rehabilitation, pain psychology, pharmacotherapy, and procedural interventions in the treatment of chronic pain. Given the current epidemic of drug-related deaths, particular emphasis is placed on the alternatives to opioid therapy. Unfortunately, death is not the only significant complication from opioid therapy, and this article discusses many of the most common side effects. This article provides general guidelines on the most appropriate utilization of opioids with emphasis on the recent Centers for Disease Control and Prevention guidelines, risk stratification, and patient monitoring. Finally, the article concludes with the critical role that a pain medicine specialist can play in the management of patients with chronic pain.

Reporting of design features and analysis details in randomized clinical trials of procedural treatments for cancer pain: An ACTTION systematic review

Background and Objectives The objective of this study was to assess the reporting of randomized clinical trials investigating procedural treatments (eg, nerve blocks, targeted drug delivery) for cancer pain, with a focus on aspects that are particularly challenging in these trials. Methods This article presents results from a systematic review of reporting of randomized clinical trials of procedural interventions for cancer pain. Articles were identified by searching PubMed from 1966 to June 2014. Data related to quality of reporting are presented for early (1985–2004) and late periods (2005–2014). Results A total of 35 published trials were included. Approximately two-thirds of the articles clearly indicated the level of blinding. Only 26% reported a primary outcome measure. Less than half explicitly reported the number of patients who completed the trial, and only 1 reported a method that was used to accommodate missing data. Almost one-third of articles included a responder analysis, all of which specified the definition of a responder. Conclusions The goal of highlighting these deficiencies in reporting is to promote transparent reporting of details affecting the completion and interpretation of procedural cancer pain trials so that their quality can be more easily evaluated.

Intrathecal Drug Delivery for Control of Pain

Over the last two decades, the use of intraspinal drug delivery (ISDD) systems for the treatment of chronic pain and spasticity has increased. The clinical practice varies from institution to institution as far as the utilization of different agents or routes of administration. The clinical approach for intraspinal drug delivery is influenced by the type of pain treated (e.g., chronic nociceptive vs. neuropathic). The choice depends on life expectancy as well as the planned time frame of treatment. Intraspinal catheter placement is frequently chosen for the treatment of cancer pain, spasticity (caused by cerebral palsy, multiple sclerosis, spinal cord injury, and other neurologic conditions), and intractable nonmalignant pain (severe post-laminectomy syndrome and arachnoiditis, vertebral compressive fractures resistant to other therapies, complex regional pain syndrome (CRPS), postherpetic neuralgia, and other types of neuralgias) and the administration of intrathecal chemotherapy and CSF drainage.