Pain
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Clinical Trial
A pharmacokinetic approach to resolving spinal and systemic contributions to epidural alfentanil analgesia and side-effects.
A pilot study was conducted in 7 normal volunteers to demonstrate the feasibility of employing pharmacokinetic tailoring to achieve matching plasma opioid concentration-time curves after epidural (e.p.) and intravenous (i.v.) alfentanil administration. Each subject participated in 1 pretest and 2 test sessions. Our pain model was cutaneous electrical stimulation of the finger and toe, adjusted to produce a baseline pain report of 5 (strong pain on a 0-5 scale). ⋯ Onset of pain relief was rapid, and duration was approximately 1.5 h with e.p. and 1 h with i.v. alfentanil. There were no differences in pupil size, ETCO2, or subjective side effects between e.p. versus i.v. administration. We conclude that systemic redistribution from the epidural space appears to account for most, but not all, of the analgesia.
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Comparative Study
Psychosocial factors discriminate multidimensional clinical groups of chronic low back pain patients.
Previous studies have empirically defined clinical subgroups of chronic low back pain (CLBP) patients, based on differing patterns of pain, disability and emotional distress. Because these identified groups generally are comparable in terms of physical and demographic variables, variation in functional status cannot be adequately explained by medical or social factors. In the present study we evaluated whether other psychosocial factors (stress, coping attempts, and satisfaction with social supports) might differentiate the observed groups. ⋯ Finally, a mixed picture of less life adversity, but more reliance on passive/avoidant coping strategies and more satisfactory social support networks was reported by patients categorized in the positive adaptation to pain group (i.e., high levels of pain, but relatively low levels of disability and depression). These findings suggest that psychosocial factors may be important and complex correlates of multidimensional clinical presentations of CLBP. Psychosocial factors may also offer an avenue for intervention across 3 key dimensions of CLBP.
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Supraspinally mediated antinociception has been clearly established for agonists acting via both micro- and delta-opioid receptors. The present experiments were undertaken to further characterize the role of supraspinal opioid delta receptors in the mediation of antinociception in rats and to examine the possible role of putative delta1- and delta2-opioid receptors in the antinociceptive effect. Cannulae directed at the right lateral ventricle, the periaqueductal gray (PAG), or the medullary reticular formation (MRF) were implanted in adult male, Sprague-Dawley rats for the microinjection of [D-Ala2,Glu4]deltorphin (delta2 agonist), [D-Pen2,D-Pen5]enkephalin (DPDPE, delta1 agonist), [D-Ser2,Leu5,Thr6]enkephalin (DSLET, mixed delta/micro agonist) or morphine (reference micro-opioid). ⋯ Morphine anticociception was not antagonized by either DALCE or Cys-DELT. These data demonstrate that supraspinal delta-opioid receptors can be activated to elicit antinociception in the rat and that opioid delta2 receptors predominate in this effect. Further, these effects may occur predominately via inhibition of supraspinally organized behavior without activation of descending systems such as those mediating the TF response in the rat.