Efficacy and safety of intravenous acetaminophen versus intravenous butorphanol as post-operative analgesic in obstetrics and gynecology: a comparative study

Vidyashri Kamath, Adeline Lasrado


Background: The purpose of this study is to provide effective pain management by administration of an analgesic that gives the patients maximum satisfaction. The goal was to evaluate and compare the analgesics efficacy of acetaminophen with butorphanol; to determine if there is an overall decrease in opioid consumption and opioid-related adverse effects; and detect any adverse effects of acetaminophen as post-operative analgesics.

Methods: In this randomized parallel-group controlled trial, post-operative patients were given either 1 g intravenous (IV) acetaminophen or 2 g IV butorphanol as post-operative analgesics. The post‑operative pain was evaluated by pain intensity scales and was measured at rest and during a deep breath over 24 h. If the reading in the pain intensity scale was above 5 then rescue medicine injection. Tramadol 100 mg IV SOS was given in both the groups. Any adverse effects reported by the patients were recorded.

Results: The butorphanol group achieved slightly better pain ratings in the first 2 h and acetaminophen group after 6 h post-operatively. The overall visual analogue scale score across time was significantly lower for acetaminophen group than the butorphanol group (p = 0.02). The secondary outcome measure, rescue analgesic consumption (injection tramadol) was comparable between the two groups. Side-effects were less in acetaminophen than butorphanol, predominantly headache and sedation which was seen in butorphanol but was absent in acetaminophen.

Conclusion: IV acetaminophen is an effective analgesic in obstetric and gynaecological surgeries with a good safety profile. When used in combination with opioids, they reduce opioid consumption, and this reduction is sufficient to reduce opioid-induced adverse effects.


Intravenous acetaminophen, Opioid analgesic, Gynaecological surgeries, Post operative analgesia

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