Pain
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This study was designed to determine whether intrathecal octreotide (sandostatin), a synthetic octapeptide derivative of somatostatin, relieved thermal hyperalgesia and reduced the evoked spinal c-Fos expression in rats with chronic constriction injury (CCI) of the sciatic nerve. Intrathecal catheters were implanted in rats 7 days before CCI of the sciatic nerve over the left hind limb. After confirmation of the development of thermal hyperalgesia by decreased paw withdrawal latencies (PWL) to heat stimulation 7 days after CCI, intrathecal sandostatin at 20, 40, and 80 microg was administered, respectively. ⋯ Expression of Fos-LI neurons in the 80 microg group was nearly completely inhibited. These data suggest that intrathecal sandostatin significantly relieved thermal hyperalgesia behaviorally but with limited effects and dose-dependently reduced spinal Fos-LI neurons expression evoked by stroking stimulation, which may reflect mechanical allodynia in rats with sciatic constriction injury. This implies that intrathecal sandostatin was effective in the treatment of neuropathic pain.
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Comparative Study
Efficacy of systemic morphine suggests a fundamental difference in the mechanisms that generate bone cancer vs inflammatory pain.
Pain is the cancer related event that is most disruptive to the cancer patient's quality of life. Although bone cancer pain is one of the most severe and common of the chronic pains that accompany breast, prostate and lung cancers, relatively little is known about the mechanisms that generate and maintain this pain. Recently, we developed a mouse model of bone cancer pain and 16 days following tumor implantation into the intramedullary space of the femur, significant bone destruction and bone cancer pain-related behaviors were observed. ⋯ Humans suffering from bone cancer pain generally require significantly higher doses of morphine as compared to individuals with inflammatory pain and in the mouse model, the doses of morphine required to block bone cancer pain-related behaviors were ten times that required to block peak inflammatory pain behaviors of comparable magnitude induced by hindpaw injection of complete Freund's adjuvant (CFA) (1-3mg/kg). As these animals were treated acutely, there was not time for morphine tolerance to develop and the rightward shift in analgesic efficacy observed in bone cancer pain vs. inflammatory pain suggests a fundamental difference in the underlying mechanisms that generate bone cancer vs. inflammatory pain. These results indicate that this model may be useful in defining drug therapies that are targeted for complex bone cancer pain syndromes.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Gabapentin in neuropathic pain syndromes: a randomised, double-blind, placebo-controlled trial.
A double-blind, randomised, placebo-controlled 8-week study was conducted to evaluate the efficacy and safety of gabapentin in the treatment of neuropathic pain, using doses up to 2400 mg/day. The study used a novel design that was symptom- rather than syndrome-based; an approach that aimed to reflect the realities of clinical practice. Participants had a wide range of neuropathic pain syndromes, with at least two of the following symptoms: allodynia, burning pain, shooting pain, or hyperalgesia. ⋯ Gabapentin was well tolerated and the majority of patients completed the study (79 versus 73% for placebo). The most common adverse events were mild to moderate dizziness and somnolence, most of which were transient and occurred during the titration phase. This study shows that gabapentin reduces pain and improves some quality-of-life measures in patients with a wide range of neuropathic pain syndromes.
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Randomized Controlled Trial Comparative Study Clinical Trial
Randomized controlled trial of botulinum toxin A for chronic myogenous orofacial pain.
The purpose of this study was to determine whether botulinum toxin A (BTX-A) was efficacious for the treatment of chronic moderate to severe jaw muscle pain in females. This was a randomized double-blind, placebo-controlled crossover trial of BTX-A. Twenty five units injected into each temporalis muscle and 50 U injected into each masseter muscle using three sites per muscle with 0.2 cm(3) per site. ⋯ Statistical significance was achieved for maximum opening without pain (P=0.02) and irrespective of pain (P=0.005) with the BTX-A arm having a relative decreased opening. No statistically significant difference was observed in any outcome measures except maximum opening, which showed BTX-A patient opening less wide than placebo. The results do not support the use of BTX-A in the treatment of moderate to severe jaw muscle pain in this patient population.