Table 1.

Summary of findings from different studies.

Author	Type of surgery	Treatment groups	Duration & timing	Outcome measures	Analgesic outcome	Opioid requirement
Khalili et al., 2013 [13]	Lower extremity surgery	15 mg/kg IV paracetamol	Preventive group: Before skin closure Preemptive group: 30 min preoperative	Pain (VRS) 5 minutes before spinal anesthesia and 6, 12, 18, and 24 hours after surgery, 24 hr meperidine consumption	Lower pain score in both preemptive and preventive acetaminophen groups at 6 hours	Opioid consumption lowest in the preemptive acetaminophen group
Hiller et al., 2012 [14]	Spinal surgery in children and adolescents	30 mg/kg IV acetaminophen infusion for 15 minutes, with a maximum dose of 1.5 g	At the end of surgery and thereafter twice at 8-hour intervals	VAS Score PCA opioid requirement	VAS score significantly lower in acetaminophen group (39%) compared to placebo group (72%) (P < 0.05)	No significant difference was found in oxycodone consumption during the 24 h postoperative period
Hynes et al., 2006 [17]	Hip arthroplasty	Propacetamol 2 g intravenously,	Two dosages, 5 h apart	Before each drug administration, for the 5 h following each study treatment administration and for the total study duration of 10 h	Significantly better pain relief with paracetamol in comparison to placebo	Significantly more number of patients in placebo group requested for rescue analgesia both at 5 hr and 10 hr
Sinatra et al., 2005 [16]	Total hip or knee replacement surgery	Acetaminophen 1000 mg Propacetamol 2000 mg Placebo	Single and repeated doses, postoperative	Pain relief (0–5) Morphine usage (PCA)	Better pain relief when compared to placebo group	Median time to first morphine rescue was also longer, reduced morphine consumption over the 24 h period
Hernández-Palazón et al., 2001 [18]	Spinal fusion surgery	Propacetamol 2000 mg Placebo	Repeated doses, postoperative	Pain intensity (VAS) Pain intensity (VRS) Morphine usage (PCA)	The relief of pain was similar at most time points	Morphine consumption was found to be 46% lower
Delbos and Boccard, 1995 [20]	Knee ligamentoplasty	Propacetamol 2000 mg Placebo	Repeated doses, postoperative	Pain intensity (VAS) Pain intensity (VRS) Morphine usage (PCA)	No difference in pain score	At 24 h, morphine consumption was found to be significantly lower
Peduto et al., 1998 [19]	Total hip arthroplasty	Propacetamol 2000 mg Placebo	Repeated doses, postoperative	Pain intensity (VAS) Pain intensity (VRS) Morphine usage (PCA)	Pain intensity was similar	Reduction in PCA morphine consumption
Granry et al., 1997 [21]	Limb surgery in children	30 mg·kg−1 propacetamol	Single injection	Visual and verbal pain scale	up to 6 hrs, both visual and verbal pain scores were significantly lower in paracetamol group