Pharmacokinetics of buccal mucosal administration of fentanyl in a carboxymethylcellulose gel compared with IV administration in dogs.

The pharmacokinetics of fentanyl administrated IV (0.01 mg/kg) and in a carboxymethylcellulose gel (0.05 mg/kg) applied to the buccal mucosa of six healthy adult medium- to large-breed dogs was evaluated. At 5 minutes after transmucosal (TM) administration, serum fentanyl levels above the therapeutic target (0.95 ng/ml) were achieved in all dogs. Except for the longer duration of serum fentanyl concentrations above the therapeutic target associated with TM administration, no significant pharmacokinetic differences were found between IV and TM fentanyl. TM fentanyl may be considered a noninvasive alternative to IV administration with rapid achievement of serum fentanyl concentrations.