Synergism between the antinociceptive effects of intrathecal midazolam and fentanyl on both A delta and C somatosympathetic reflexes.
The interaction between the antinociceptive effects of fentanyl and midazolam, administered intrathecally (i.t.), was examined in dogs. Midazolam 1 mg (i.t) depressed the A delta and C fibre mediated somatosympathetic reflexes to 68.3 and 85.2% of control values and then reduced the subsequent doses of fentanyl (i.t.) required to abolish these reflexes by 50%. After midazolam (1 mg, i.t.) the ED values for fentanyl were markedly less than the theoretical predicted additive values. This indicates synergism between the effects of fentanyl and midazolam.
Wang
C
C
Department of Anaesthetics, Hammersmith Hospital, Royal Postgraduate Medical School, London, U.K.
Chakrabarti
M K
MK
Whitwam
J G
JG
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004558:Electric Stimulation; D005283:Fentanyl / Q000494:pharmacology*; D007278:Injections, Spinal; D008874:Midazolam / Q000494:pharmacology*; D009412:Nerve Fibers / Q000187:drug effects*; D009413:Nerve Fibers, Myelinated / Q000187:drug effects*; D011826:Radial Nerve / Q000502:physiology; D012018:Reflex / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects*; D013979:Tibial Nerve / Q000502:physiology
D000700:Analgesics; D008874:Midazolam; D005283:Fentanyl