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The Effect of Paracetamol and Tropisetron on Pain: Experimental Studies and a Review of Published Data
Author(s) -
Tiippana Elina,
Hamunen Katri,
Kontinen Vesa,
Kalso Eija
Publication year - 2013
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/j.1742-7843.2012.00935.x
Subject(s) - tropisetron , analgesic , cold pressor test , medicine , anesthesia , serotonergic , pain tolerance , crossover study , saline , pharmacology , threshold of pain , serotonin , heart rate , blood pressure , placebo , receptor , alternative medicine , pathology
Experimental studies suggest that paracetamol‐induced analgesia is mediated via central serotonergic pathways and attenuated by 5‐ HT 3‐antagonists. However, clinical studies do not support this, and 5‐ HT 3‐antagonists are expected to reduce pain by blocking the descending pronociceptive pathway. The current project tested whether tropisetron attenuates analgesia by paracetamol. Two randomized, double‐blind, crossover studies with 18 healthy male volunteers in each were performed. Pain stimuli were cold water immersion (cold pressor test), contact heat pain (study 1) and electrical stimulation (study 2). In both studies, tropisetron 5 mg i.v. or saline was administered, followed by paracetamol 2 g i.v. 30 min. later. Individual changes in heat and cold pain intensity, cold pain tolerance and unpleasantness were recorded. The same thresholds were also expressed as scores (% of the individual score at baseline). Additionally, previously published findings on the effects of paracetamol and its interaction with 5 HT 3‐antagonists in human experimental pain models were reviewed. After calculation of the sensory and pain scores (%), tropisetron seemed to amplify the analgesic action of paracetamol. Paracetamol 2 g i.v. did not show any statistically significant analgesia in thermal tests (study 1), or differences in sensory, pain detection or moderate pain thresholds of the electrical stimulus (study 2). As paracetamol did not have a measurable analgesic effect in these tests, no conclusions can be drawn about the interaction between paracetamol and tropisetron. However, tropisetron may have an analgesic effect of its own. Clinicians should not avoid using these drugs together, unless larger clinical studies indicate otherwise.