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Biomedical subjects

Karin L Petersen

Publications and source records attributed to Karin L Petersen.

7 recordsLinked to original sources
PubMed2003

A randomized study of the effect of oral lamotrigine and hydromorphone on pain and hyperalgesia following heat/capsaicin sensitization.

In this randomized double-blind placebo-controlled study, the analgesic effect of oral lamotrigine (400 mg) on cutaneous sensitization induced with the heat/capsaicin sensitization model was compared with the effect of oral hydromorphone (8 mg) in healthy volunteers. In a separate session, intravenous remifentanil (0.10 microg.kg(-1).min(-1)) and placebo were administered. This session was used as an additional reference comparator. Outcome measures were the areas of secondary hyperalgesia to brush and von Frey hair stimulation and the painfulness of noxious thermal stimulation in nonsensitized skin. Compared with placebo, both intravenous remifentanil and oral hydromorphone significantly suppressed secondary hyperalgesia and acute thermal nociception. Oral lamotrigine did not reduce secondary hyperalgesia or acute thermal nociception but produced side effects of severity comparable with that of oral hydromorphone. Although lamotrigine is efficacious in the management of some types of chronic neuropathic pain, the lack of effect of this agent on human experimental pain suggests that its analgesic effects depend on nerve injury-associated abnormalities, which cannot be simulated in healthy human volunteers.

Adult↗
PubMed2003

The heat/capsaicin sensitization model: a methodologic study.

The heat/capsaicin sensitization model induces cutaneous sensitization by using a combination of heat and topical capsaicin. It has been suggested that the stability and duration of the cutaneous sensitization are due to a synergistic effect between heat and capsaicin. The aim of this study was to evaluate a possible synergistic effect between heat and capsaicin in inducing cutaneous sensitization. Twenty healthy male volunteers completed this random order, 4-session study. Three different stimulation combinations were used to induce cutaneous sensitization: day A, heat and capsaicin; day B, heat alone; day C, capsaicin alone. Combination A was repeated on day D to determine between day reproducibility. Rekindling was performed 3 times at 40-minute intervals to maintain stable areas of secondary hyperalgesia. Brief thermal sensitization (45 degrees C for 3 minutes) was induced at each session. Within and between day reproducibility was calculated. There was no difference between the size of areas of secondary hyperalgesia after stimulation with heat/capsaicin compared to heat and capsaicin stimulation alone. The within day reproducibility was better with heat/capsaicin than with either stimulation alone. There was no synergistic or additive effect between heat and capsaicin in inducing cutaneous sensitization. Rekindling seems to be the important factor in maintaining stable and long-lasting cutaneous sensitization.

Adolescent↗
PubMed2002

Relief of post-herpetic neuralgia by surgical removal of painful skin.

We present a case of longstanding PHN treated by skin excision of the area of greatest pain (11.3 x 26.0 cm(2)). The operation reduced pain, eliminated tactile allodynia, and facilitated greatly reduced medication use over a 1-year follow-up period. Fourteen punch biopsies and 10 strips of skin (each 10 mm long) from the excised painful PHN skin were qualitatively assessed by double-label immunofluorescence using antibodies against protein-gene-product 9.5 (PGP9.5), 200 kDa neurofilament protein (NF), calcitonin gene-related peptide (CGRP) and vanilloid receptor-1 (VR-1). Compared with a punch biopsy from mirror image skin, the pattern of cutaneous innervation in PHN skin was consistently and substantially different. The results may explain the anatomical basis of the capsaicin-response test and have implications for our understanding of clinical mechanisms underlying PHN pain.

Aged↗
PubMed2002

Gabapentin suppresses cutaneous hyperalgesia following heat-capsaicin sensitization.

BACKGROUND: The anticonvulsant gabapentin, proven effective for neuropathic pain in two large, placebo-controlled clinical trials, is widely used for treatment of chronic pain. Preclinical studies have demonstrated analgesic and antiallodynic effects in models involving neuronal sensitization and nerve injury, without affecting acute pain transmission. The aim of the present study was to link data from animal models and clinical trials for chronic pain by investigating the effect of gabapentin on acute nociception and experimentally induced cutaneous hyperalgesia in healthy volunteers. METHODS: The human experimental hyperalgesia model, the heat-capsaicin sensitization model, was induced in 25 healthy male volunteers. Subjects received oral gabapentin (1,200 mg) or placebo after heat-capsaicin sensitization was established on the forearm. The primary outcome measures were the sizes of the areas of secondary hyperalgesia to von Frey hair and brush stimulation on the forearm. Secondary outcome measures were as follows: (1) size of secondary hyperalgesia area in response to brief thermal sensitization procedure on the thigh; (2) heat pain detection thresholds in normal and sensitized skin; and (3) painfulness of 1 min of 45 degrees C stimulation in normal skin. RESULTS: Oral gabapentin profoundly suppressed established cutaneous sensitization on the forearm and prevented development of cutaneous sensitization on the thigh. Thermal nociception in normal skin was unchanged. Side effects were modest. CONCLUSION: The results link preclinical findings with results from clinical trials of neuropathic pain. The results further suggest that gabapentin may prove effective in acute pain disorders involving neuronal sensitization, such as postoperative pain and acute herpetic pain, and could prove effective in prevention of chronic pain.

Acetates↗
PubMed2000

Capsaicin evoked pain and allodynia in post-herpetic neuralgia.

The hypothesis that the pain and allodynia associated with post-herpetic neuralgia (PHN) is maintained by a combination of input from preserved primary afferent nociceptors and sensitization of central pain transmitting neurons was examined in 17 subjects with PHN. Pain, allodynia, thermal sensory function, cutaneous innervation, and response to controlled application of 0.075% capsaicin were measured. Compared to mirror-image skin, applying capsaicin on a 9 cm(2) area of PHN skin significantly increased overall PHN pain and allodynia in 11 of 17 subjects. These 'capsaicin responders' were characterized by higher average daily pain, higher allodynia ratings, and relatively preserved sensory function at baseline compared to the non-responders. In three of the 'capsaicin responders' the area of allodynia expanded into previously non-allodynic and non-painful skin that had normal sensory function and cutaneous innervation. These observations support the hypothesis that allodynia in some PHN patients is a form of chronic secondary hyperalgesia maintained by input from intact and possibly 'irritable' primary afferent nociceptors to a sensitized CNS.

Administration, Topical↗
PubMed1994

Quantitative sensory examination of epidural anaesthesia and analgesia in man: combination of morphine and bupivacaine.

The effect of epidural administration of a combination of low-dose morphine (2 mg) and bupivacaine (25 mg) on somatosensory and motor functions was examined in 13 healthy volunteers. The study design was a double-blind 4-way cross-over in which combined treatment was compared with either drug used alone or placebo. Every 2nd hour for 10 h effects on nociceptive and non-nociceptive somatosensory functions were quantified with 12 psychophysical measures. In addition knee extension strength, reaction time and skin temperature were examined. Epidural bupivacaine had hypoalgesic effect in all nociceptive tests, whereas epidural morphine only demonstrated hypoalgesic properties in nociceptive test with prolonged stimuli. In comparison with bupivacaine alone the combination treatment had a lesser peak effect but a more prolonged hypoalgesic action. In comparison with morphine alone the combination treatment induced a faster onset and demonstrated a modest increase in hypoalgesic effect in a subset of the test, even beyond the duration of bupivacaine when administered alone. Motor function was not attenuated by any of the treatments. Mechanisms of interaction between morphine and bupivacaine as well as their possible clinical implications are discussed.

Adolescent↗