Opioids
| Drug and Dose | Method | Comment | References |
|---|---|---|---|
| Alfentanil | |||
| Bolus 7 μg/kg followed by infusion 0.6 μg/kg/min for 20 min | Heat and cold stimulations and mechanical allodynia/hyperalgesia in response to heat/cold stimulation in 12 patients with neuropathic pain. | Allodynia and hyperalgesia to cold as well as allodynia to mechanical stimulation were reduced. Heat pain detection threshold was elevated. | Jørum et al. (2003) |
| Single infusion via computer controlled pump, programmed to target plasma levels of 25, 50 and 75 ng/ml i.v. | Thermal stimulation, pain in response to pinprick and hyperalgesic area were measured in 12 patients with neuropathic pain. | Cold pain threshold increased, whereas there was no effect on heat pain thresholds. There was a reduction in pinprick pain and in stroking-evoked allodynic area. This was not the case for von Frey evoked allodynic area, where no effect was observed. | Leung et al. (2001) |
| Meperidine | |||
| 100 mg single dose | Electrical stimulation in 20 patients with dental pain. | No significant effect. | Carnes et al. (1998) |
| Morphine | |||
| 0.075 mg/kg i.v. single dose | Brush (allodynia), repeatedly pricking the affected skin area with von Frey, tactile von Frey stimulation, and thermal stimulation in cervical, thoracic, lumbar, and facial regions in eight patients with postherpetic neuralgia. | No significant change in pain thresholds for thermal or tactile sensation. Allodynia was significantly decreased. Pain to repeated pricking stimulation was significantly increased. | Eide et al. (1994) |
| 30 mg oral single dose | Mechanical, thermal, and electrical stimulation in the skin, muscles (no heat), and esophagus 10 in patients with chronic pancreatitis. | In esophagus mechanical pain tolerance threshold was increased but heat and electrical evoked pain were unaffected. No effects in skin and muscle pain. | Staahl et al. (2007) |
| Continuous infusion for 48 h resulting in a total of 60.7 ± 18 mg i.v. | Rectal distension and transcutaneous electrical skin stimulation in 50 patients undergoing abdominal hysterectomies. | Increased pain tolerance to rectal distension. No difference in trans-cutaneous electrical stimulation. | Wilder-Smith et al. (1999a) |
| 10 mg four times daily | Rectal distension thresholds in 25 patients with chronic pancreatitis pain. | No significant effect. | Wilder-Smith et al. (1999b) |
| 10 mg i.v. single dose | Pressure stimulation at tender and control points in nine patients with fibromyalgia. | No significant effect. | Sörensen et al. (1995) |
| 0.3 mg/kg i.v. single dose | Pressure stimulation at tender and nontender point areas in 18 patients with fibromyalgia. | Patients were classified as responders or nonresponders according to clinical pain intensity ratings taken before, during, and after the tests. Pressure pain thresholds significantly increased in responders but not in nonresponders. | Sörensen et al. (1997) |
| 0.3 mg/kg 30 min infusion | Pressure, intramuscular, and cutaneous electrical stimulation was recorded in 17 patients with diagnosed whiplash-syndrome. | No significant effects. | Lemming et al. (2005) |
| Oxycodone | |||
| 15 mg oral single dose | Mechanical, thermal, and electrical stimulation in the skin, muscles (no heat), and esophagus in 10 patients with chronic pancreatitis | Mechanical and heat pain tolerance threshold were increased in skin. In muscles, mechanical pain tolerance threshold was increased. In esophagus, mechanical and heat pain thresholds were increased. Electrical pain thresholds were unaffected in all tissue. | Staahl et al. (2007) |
| Fentanyl | |||
| High dose (112 μg bolus followed by 0.04 μg/kg/min infusion) or low dose (56 μg bolus followed by 0.02 μg/kg/min infusion) | Rectal distension in 10 patients with IBS. | Perception thresholds increased dose-dependently. | Lembo et al. (2000) |
| 0.8 and 1.1 μg/kg single doses | Heat stimulation of the skin to 12 patients with low back pain. | Reduced pain responses. | Price et al. (1986) |
| 0.75 or 1.5 μg/kg i.v. single dose | Heat (single and repeated) and cold (pulse) stimulation of the skin in 15 patients with fibromyalgia. | Only repeated cold pain was attenuated. | Price et al. (2002) |
| 3 μg/kg i.v. single short infusion | Electrical stimulation in the skin in 15 patients undergoing back surgery. | Pain thresholds were increased. | Wilder-Smith et al. (1996) |
| 1.5 μg/kg | Electrical skin stimulation in 15 patients after abdominal hysterectomy | All thresholds were increased. | Wilder-Smith et al. (1998) |
| Asimadoline | |||
| 0.5 mg | Phasic distension of colon in 20 patients with IBS. | Area under curve of pain intensity decreased significantly. | Delvaux et al. (2004) |
| Fedotozine | |||
| 100 mg | Phasic distention of colon in 14 patients with IBS. | Thresholds of perception were increased. | Delvaux et al. (1999) |
| Tramadol | |||
| 100 mg | Electrical stimulation at or distant from the incision were studied in 120 patients who had elective cesarean delivery | No significant differences for tramadol, but an increase was seen for the combination tramadol plus diclofenac. | Wilder-Smith et al. (2003) |
| 732.5 ± 152 mg i.v. | Rectal distension and transcutaneous electrical stimulation in 50 patients undergoing abdominal hysterectomies | No significant effects. | Wilder-Smith et al. (1999a) |
| 50 mg four times daily | Rectal distension in 25 patients with chronic pancreatitis pain. | Rectal distension thresholds increased. | Wilder-Smith et al. (1999b) |
| 100 mg p.o. | Electrical skin stimulation in 60 patients with osteoarthritis. | Reduced pain thresholds. | Wilder-Smith et al. (2001) |