The journal of pain : official journal of the American Pain Society
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Case Reports
Use of oxcarbazepine to treat a pediatric patient with resistant complex regional pain syndrome.
We describe a 12-year-old patient with severe, protracted complex regional pain syndrome type I. His pain did not respond to gabapentin, amitriptyline, physical therapy, opioids, or nonsteroidal drugs. Sympathetic or regional block was not attempted because of persistent bacteremia and severe local sepsis. His pain responded dramatically to the addition of oxcarbazepine, with rapid improvement in his symptoms and functional status. We suggest that oxcarbazepine might be a useful adjunct in the treatment of gabapentin-resistant complex regional pain syndrome type I in children and should be considered. ⋯ Oxcarbazepine's antinociceptive effect is mediated via sodium channel inhibition in neuropathic models and by inhibition of substance P and prostaglandins in anti-inflammatory models. The efficacy of oxcarbazepine in this patient might be attributable to these mechanisms or possibly to synergism with either gabapentin or the anti-inflammatory effects produced by amitriptyline.
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In this study we investigated the involvement of cutaneous versus knee joint afferents in the antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS) by differentially blocking primary afferents with local anesthetics. Hyperalgesia was induced in rats by inflaming one knee joint with 3% kaolin-carrageenan and assessed by measuring paw withdrawal latency to heat before and 4 hours after injection. Skin surrounding the inflamed knee joint was anesthetized using an anesthetic cream (EMLA). Low (4 Hz) or high (100 Hz) frequency TENS was then applied to the anesthetized skin. In another group, 2% lidocaine gel was injected into the inflamed knee joint, and low or high frequency TENS was applied. Control experiments were done using vehicles. In control and EMLA groups, both low and high frequency TENS completely reversed hyperalgesia. However, injection of lidocaine into the knee joint prevented antihyperalgesia produced by both low and high frequency TENS. Recordings of cord dorsum potentials showed that both low and high frequency TENS at sensory intensity activates only large diameter afferent fibers. Increasing intensity to twice the motor threshold recruits Adelta afferent fibers. Furthermore, application of EMLA cream to the skin reduces the amplitude of the cord dorsum potential by 40% to 70% for both high and low frequency TENS, confirming a loss of large diameter primary afferent input after EMLA is applied to the skin. Thus, inactivation of joint afferents, but not cutaneous afferents, prevents the antihyperalgesia effects of TENS. We conclude that large diameter primary afferent fibers from deep tissue are required and that activation of cutaneous afferents is not sufficient for TENS-induced antihyperalgesia. ⋯ Transcutaneous electrical nerve stimulation (TENS) is an accepted clinical modality used for pain relief. It is generally believed that TENS analgesia is caused mainly by cutaneous afferent activation. In this study by differentially blocking cutaneous and deep tissue primary afferents, we show that the activation of large diameter primary afferents from deep somatic tissues, and not cutaneous afferents, are pivotal in causing TENS analgesia.
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OxyContin (Purdue Pharma L.P., Stamford, Conn) was approved by the Food and Drug Administration (FDA) in 1995 as a sustained-release preparation of oxycodone hydrochloride and was thought to have much lower abuse potential than immediate-release oxycodone because of its slow-release properties. However, beginning in 2000, widespread reports of OxyContin abuse surfaced. In response, Purdue Pharma L.P. sponsored the development of a proactive abuse surveillance program, named the Researched Abuse, Diversion and Addiction-Related Surveillance (RADARS) system. In this paper, we describe results obtained from one aspect of RADARS--the use of drug abuse experts (ie, key informants)--as a source of data on the prevalence and magnitude of abuse of prescription drugs. The results indicate that prescription drug abuse has become prevalent, with cases reported in 60% of the zip codes surveyed. The prevalence of abuse was rank ordered as follows: OxyContin >or= hydrocodone > other oxycodone > methadone > morphine > hydromorphone > fentanyl > buprenorphine. In terms of the magnitude of abuse (>or=5 cases/100,000 persons in a 3-digit zip code), modest growth was seen with all analgesics over the 10 calendar quarters we monitored, but was most pronounced with OxyContin and hydrocodone. These results indicate that OxyContin abuse is a pervasive problem in this country, but that it needs to be considered in the context of a general pattern of increasing prescription drug abuse. ⋯ Over the past 5 years, there have been reports, frequently anecdotal, that opioid analgesic abuse has evolved into a national epidemic. In this study, we report systematic data to indicate that opioid analgesic abuse has in fact increased among street and recreational drug users, with OxyContin and hydrocodone products the most frequently abused. Steps need to be taken to reduce prescription drug abuse, but very great care needs to be exercised in the nature of these actions so the legitimate and appropriate use of these drugs in the treatment of pain is not compromised as a result.
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Scheduled dosing of opioids is believed to provide more effective analgesia when compared to as needed (PRN) administration of the drug; however, few studies have evaluated the value of this approach. Therefore, a quality improvement study was conducted to determine the efficacy and safety of scheduled dosing of opioid analgesics, using a 2-group parallel design. One medical unit in a large urban academic medical center employed scheduled dosing, whereas a comparable unit used PRN dosing. The primary outcome indicators included pain intensity ratings and opioid doses, along with adverse events. Scheduled dosing was associated with decreased pain intensity ratings. There were no statistically significant differences in the amount of opioid ordered, or the amount administered when comparing scheduled vs. PRN dosing. However, when the amount of opioid given was expressed as a percentage of the amount ordered, the difference between scheduled (70.8%) and PRN (38%) dosing was statistically significant (P = .0001). There was no difference in adverse events between the 2 groups. These findings suggest that scheduled dosing of opioids in an inpatient medical population provides improved analgesia with no increased risk of adverse events. ⋯ Scheduled dosing of opioids in an inpatient medical population improves analgesia, theoretically by overcoming barriers to drug administration, as well as providing more stable plasma levels of the opioid.