Free and nanoencapsulated meloxicam as an adjuvant in intraoperative and postoperative analgesia in bicthes undergoing ovariohysterectomy

Nanocarriers have the ability to increase the bioavailability of drugs, decreasing the necessary dose and adverse effects. This prospective clinical study aimed to assess the efficacy of analgesia provided by free meloxicam and nanoencapsulated meloxicam during both the intraoperative and postoperative phases of ovariohysterectomy (OH) in female dogs. Twenty healthy dogs were randomly allocated to the FM group (free meloxicam - 0.2 mg/kg) or to the MNano group (meloxicam loaded-nanocapsules - 0.2 mg/kg). Both groups received the formulations orally four hours before the surgical procedure. During the OH surgeries, intraoperative analgesia was measured using elevated heart rate and mean arterial pressure. The pain after surgery was measured using the short form of the Glasgow Composite Pain Scale and Visual Analog Scale in the first 48 hours. Platelet function was measured through a buccal mucosal bleeding time test before meloxicam administration, four hours after that administration, at the end of the OH, and 12 hours after taking the medication. In addition, creatinine was measured preoperatively, 24 and 48 hours after meloxicam administration. The distribution of rescue analgesia in the intraoperative period showed no difference between groups. No patient required supplemental analgesia in the postoperative period. There was no difference between groups in postoperative pain assessment scales, buccal mucosal bleeding time, or creatinine. However, three dogs of the FM group presented vomiting (2/10) and faecal constipation followed by haematochezia (1/10). Both free meloxicam and the new formulation of nano-encapsulated meloxicam promoted satisfactory postoperative analgesia in healthy dogs submitted to OH when administered orally, in a single dose, four hours before the surgical procedure. Only animals treated with free meloxicam had side effects related to the gastrointestinal tract in the postoperative period, indicating that the nanostructured formulation may be is safe and effective as an alternative to commercial products.