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Keywords:

  • angiotensin-converting enzyme inhibitor;
  • benazepril;
  • dogs;
  • pharmacokinetics;
  • switchability

Objective

To compare the bioequivalence and ‘switchability’ of two formulations of benazepril (tablet and liquid) after oral administration.

Design

Randomised cross-over design, followed by parallel comparison.

Methods

Twelve mixed-breed dogs were administered either a tablet (Group A) or liquid formulation (Group B) of benazepril orally at 0.45 mg/kg daily for 4 days. With no washout period, the dogs then received the alternative treatment at the same dose for a further 4 days. Blood samples taken prior to treatment and serially after treatment were analysed for plasma concentrations of benazepril and benazeprilat and the activity and concentration of angiotensin-converting enzyme (ACE). The calculated percentage inhibition of ACE was defined as the primary outcome variable.

Results

No statistically significant differences were found between groups A and B for any variable evaluated. The mean (± SD) percentage of ACE inhibition was 85.5 ± 7.04% for the liquid formulation and 85.9 ± 6.66% for the tablet formulation. The mean of the ratios was 1.00 (80% confidence interval 0.96–1.04). No evaluated effect term (sequence, formulation or period) had any statistical effect on any outcome variable.

Conclusion

This study supports a conclusion that, based on pharmacodynamic response, the liquid formulation of benazepril is bioequivalent to the reference tablet formulation. Further, the lack of a sequence effect supports the switchability of these two formulations.