Simple devices in differentiating the effects of buprenorphine and fentanyl in healthy volunteers.

We have tested the usefulness of the critical flicker fusion threshold-test (CFF), Maddox wing readings (MW), and visual analogue scale scores (VAS) in a double-blind, random-order study designed to evaluate the clinical effects of two different kinds of opiates, buprenorphine and fentanyl in comparison with those of placebo. The results were compared with the so-called postanaesthetic recovery score (PARS). In 7 healthy volunteers MW and VAS differentiated the effects of buprenorphine 7.5 micrograms/kg i.v. from those of fentanyl 2.5 micrograms/kg i.v. and placebo. CFF was very insensitive in this respect and PARS completely useless. Our results show that, in addition to the known usefulness of VAS, MW is also able to differentiate the effects of these opiates.