The effect of repeated intramuscular alfentanil injections on experimental pain and abuse liability indices in healthy males

David Andrew Tompkins, Michael T. Smith, George E. Bigelow, Ruin Moaddel, Swarajya Lakshmi Vatem Venkata, Eric C. Strain

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


OBJECTIVE:: Opioid-induced hyperalgesia (OIH), increased sensitivity to noxious stimuli after repeated opioid exposures, has been demonstrated in preclinical studies. However, there is no accepted, prospective model of OIH after repeated opioid exposures currently available in humans. This study assessed a potential prospective OIH model. METHODS:: Double-blind intramuscular injections of a short-acting opioid (alfentanil 15 mcg/kg; N=8) were compared to active placebo (diphenhydramine 25 mg; N=3) on cold and pressure pain testing and standard abuse liability measures in eight 10-hour sessions (1 injection/session) over 4 to 5 weeks in healthy, pain-free males. Decreases from session baseline pain threshold (PThr) and tolerance (PTol) were calculated to represent hyperalgesia, and were assessed both within and across sessions. RESULTS:: Mean decreases in cold PTol were seen in the alfentanil group at 180 minutes (-3.8 s, ±26.5) and 480 minutes (-1.63 s, ±31.5) after drug administration. There was a trend for differences between conditions on cold PThr hyperalgesia but not for pressure PThr. Alfentanil participants had greater mean ratings on Liking and High visual analog scales at peak effects (30 min), but these scores did not change across sessions. DISCUSSION:: Repeated alfentanil exposures over 4 to 5 weeks resulted in within session decreases in cold pain tolerance from baseline but these differences were not substantially different from diphenhydramine controls. The results did not support the phenomenon of OIH in this model, although definitive conclusions regarding the existence of OIH in humans likely requires a larger sample size or an alternative model.

Original languageEnglish (US)
Pages (from-to)36-45
Number of pages10
JournalClinical Journal of Pain
Issue number1
StatePublished - Jan 2014


  • abuse liability
  • alfentanil
  • algometer
  • cold pressor
  • opioid-induced hyperalgesia

ASJC Scopus subject areas

  • Clinical Neurology
  • Anesthesiology and Pain Medicine


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