Pain
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Comparative Study
Peripheral interactions between dextromethorphan, ketamine and amitriptyline on formalin-evoked behaviors and paw edema in rats.
The local, peripheral administration of antidepressants and excitatory amino acid receptor antagonists can cause analgesia in a number of conditions. The present study examined the effects of combinations of dextromethorphan and ketamine, two clinically used N-methyl-D-aspartate (NMDA) receptor antagonists, with amitriptyline on formalin-evoked behaviors and paw edema. Pretreatment with amitriptyline or dextromethorphan (10-300 nmol) resulted in suppression of flinching behaviors induced by 2.5% formalin, but ketamine had no intrinsic effect. ⋯ NMDA receptor blockade, blockage of sodium channels, blockage of biogenic amine receptors), while a lack of intensification (amitriptyline/ketamine) could reflect occluded actions due to expression of similar actions by the other drug. Paw edema induced by dextromethorphan and ketamine involves inhibition of biogenic amine reuptake, and the ability of amitriptyline to block biogenic amine receptors likely accounts for its inhibiton of these actions. Combinations of these particular agents could represent a method for augmented analgesia and minimization of local adverse reactions.
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Comparative Study
Temporal summation of pain from mechanical stimulation of muscle tissue in normal controls and subjects with fibromyalgia syndrome.
Individuals diagnosed with fibromyalgia syndrome (FMS) report chronic pain that is frequently worsened by physical activity and improved by rest. Palpation of muscle and tendinous structures suggests that nociceptors in deep tissues are abnormally sensitive in FMS, but methods of controlled mechanical stimulation of muscles are needed to better characterize the sensitivity of deep tissues. Accordingly, force-controlled mechanical stimulation was applied to the flexor digitorum muscle of the forearm in a series of brief contacts (15 stimuli, each of 1s duration, at 3 or 5s interstimulus intervals). ⋯ Furthermore, painful after-sensations were greater in amplitude and more prolonged for FMS subjects. These observations complement a previous demonstration that temporal summation of pain and after-sensations elicited by thermal stimulation of the skin are moderately enhanced for FMS subjects. Abnormal input from muscle nociceptors appears to underlie production of central sensitization in FMS that generalizes to input from cutaneous nociceptors.
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Comparative Study
Transgene-mediated enkephalin release enhances the effect of morphine and evades tolerance to produce a sustained antiallodynic effect in neuropathic pain.
We examined the pharmacologic characteristics of herpes simplex virus (HSV) vector-mediated expression of proenkephalin in the dorsal root ganglion in a rodent model of neuropathic pain. We found that: (i). vector-mediated enkephalin produced an antiallodynic effect that was reversed by naloxone; (ii). vector-mediated enkephalin production in animals with spinal nerve ligation prevented the induction of c-fos expression in second order sensory neurons in the dorsal horn of spinal cord; (iii). the effect of vector-mediated enkephalin enhanced the effect of morphine, reducing the ED(50) of morphine 10-fold; (iv). animals did not develop tolerance to the continued production of vector-mediated enkephalin over a period of several weeks; and, (v). vector transduction continued to provide an analgesic effect despite the induction of tolerance to morphine. This is the first demonstration of gene transfer to provide an analgesic effect in neuropathic pain. The pharmacologic analysis demonstrates that transgene-mediated expression and local release of opioid peptides produce some effects that are distinct from peptide analogues delivered pharmacologically.
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Case Reports
Musculoskeletal pain in the Netherlands: prevalences, consequences and risk groups, the DMC(3)-study.
The objective of this paper was to present estimates on the prevalence of musculoskeletal pain of five different anatomical areas and ten anatomical sites, and their consequences and risk groups in the general Dutch population. Cross-sectional data from a population-based study of a sex-age stratified sample of Dutch inhabitants of 25 years and older were used. With a postal questionnaire data was assessed on musculoskeletal pain, additional pain characteristics (location, duration, course), its consequences (utilization of health care, sick leave and limitation in daily life) and general socio-demographic characteristics. ⋯ Between 33 and 42% of those with complaints consulted their general practitioner about their pain. With the exception of persons who are work disabled, general sociodemographic characteristics cannot be used to identify high risk groups. Musculoskeletal pain is common in all subgroups of the population and has far-reaching consequences for health, work and the use of health care.
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Case Reports
Management of chronic intractable angina - spinal opioids offer an alternative therapy.
The successful treatment of chronic intractable angina by spinally administered opioids via an Algomed drug delivery device (hereinafter called the pump) is reported in seven patients. All patients had at least two prior cardiac surgeries and the duration of minimally controlled chronic intractable angina varied from 5 to 19 years prior to spinally administered opioids. ⋯ The opioid used was either morphine or fentanyl and the dose increase (either mg/year or microg/year, respectively) varied from 1.2 to 16. We suggest that bolus spinal morphine or fentanyl administered via the pump is a viable alternative for the effective control of angina when more established therapies have been found to provide insufficient pain relief.