**2. Multimodal analgesia**

#### **2.1 Acetaminophen**

Acetaminophen is one of the most prescribed analgesics worldwide, it has an excellent safety profile and relatively few adverse effects. Its action mechanism for inhibiting acute postoperative pain has not been elucidated completely, however, it is believed to inhibit the cyclooxygenase (COX) enzyme and modulate the receptors Transient Receptor Potential Vanilloid 1 (TRPV1) and Cannabinoid 1 (CB1) in the midbrain, medulla and spinal cord which are mediators of pain modulation. It is usually administered via oral or IV routes, there is no difference in area under the curve and *t*½ between both routes, thereby being effective for analgesia in both presentations [3]. Recent guidelines establish that acetaminophen should be administered preoperatively (most easily oral), intraoperatively and should be continued in the postoperative period [4]. Established doses are 1000 mg every 6–8 hours, with a maximum established dose of 4000 mg per 24 hours [5].
