Conscious sedation and analgesia with rectal ketamine in the Macaca fuscata monkey

Conscious sedation is commonly utilized in pediatric dentistry. Although opioid analgesics are often employed, patient safety would be enhanced if nonopioid drugs were used. The purpose of this study was to determine if rectal ketamine could produce plasma concentrations that would achieve both conscious sedation and analgesia to gingival needle puncture. Five 2-year-old male Macaca fuscata monkeys were given rectal ketamine at a dosage of 60 mg/kg and 90 mg/kg one week apart. Blood was drawn at selected times after administration, and vital signs, level of sedation, and consciousness were assessed. Plasma ketamine concentrations ranged from 240 to 820 ng/mL and from 390 to 3120 ng/mL after rectal administration at doses of 60 mg/kg and 90 mg/kg, respectively. Two monkeys after the high dose showed analgesia to a gingival needle puncture at plasma ketamine concentrations that ranged from 1390 to 3120 ng/mL. A good level of sedation was consistently observed in four monkeys (80%) following rectal ketamine at a dosage of 90 mg/kg, whereas one monkey showed a consistently good level at a dosage of 60 mg/kg. Sedation and dose were significantly (P < 0.001) associated with plasma ketamine concentrations; physiologic parameters were not (P > 0.05). The results of this study suggest that rectal ketamine can produce plasma concentrations of the drug sufficient to achieve sedation in the monkey. The attainment of concomitant analgesia to a gingival needle puncture was not as predictable.