The electroencephalographic changes and analgesic efficacy of metamizole-sodium via transdermal route administration was studied on twelve Nigeria indigenous neutered dogs, randomly divided into three treatment groups of four dogs each. Treatments group I and II had metamizole-sodium, administered intramuscularly 8-h interval in 24-h at 25 mg/kg, and via the transdermal patch ones at 75 mg/kg respectively. The control group had 5 ml normal saline intramuscularly. Preanaesthesia and anaesthesia were achieved by propofol (5 mg/kg) and rescue analgesia given to dogs that experience pain in the placebo group. Quantitative electroencephalographic theta and alpha wave mappings, rectal temperature, heart rate and respiratory rate were monitored. There was no significant difference (P > 0. 05) in the theta wave for the fronto-parietal lobe of Group II when compared to Group I. The alpha wave showed a significant decrease (P ˂ 0. 001) at 6-h post-surgery for the Group II (0.20 ± 0.100 Hz) compare to Group I (360.00 ± 221.00 Hz). Theta wave recorded in the thalamocortical lobe, however, decreased (P ˂ 0. 05) at 18-h post-surgery in Group II (6.00 ± 5.00 Hz) compare to the group I (1399.00 ± 577.00 Hz) and at 24-h post-surgery (7.00 ± 4.00 Hz) compare to (432.00 ± 173.00 Hz) respectively. The alpha wave showed a significant decrease (P ˂ 0.001) in Group II (0.09 ± 0.04 Hz) at 6-h post-surgery compare to Group I (432.00 ± 173.00 Hz). There were no significant differences in the vital parameters. Metamizole-sodium at 75 mg/kg via transdermal routes, provide analgesic effects in neutered dogs at the dose tested.
Key words: Electroencephalographic, metamizole-sodium, transdermal route, neutered dogs, pain.
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