Pharmacokinetic evaluation of novel midazolam gel formulations following buccal administration to healthy dogs

Am J Vet Res. 2018 Jan;79(1):73-82. doi: 10.2460/ajvr.79.1.73.

Abstract

OBJECTIVE To determine the physiochemical properties and pharmacokinetics of 3 midazolam gel formulations following buccal administration to dogs. ANIMALS 5 healthy adult hounds. PROCEDURES In phase 1 of a 2-phase study, 2 gel formulations were developed that contained 1% midazolam in a poloxamer 407 (P1) or hydroxypropyl methylcellulose (H1) base and underwent rheological and in vitro release analyses. Each formulation was buccally administered to 5 dogs such that 0.3 mg of midazolam/kg was delivered. Each dog also received midazolam hydrochloride (0.3 mg/kg, IV). There was a 3-day interval between treatments. Blood samples were collected immediately before and at predetermined times for 8 hours after drug administration for determination of plasma midazolam concentration and pharmacokinetic analysis. During phase 2, a gel containing 2% midazolam in a hydroxypropyl methylcellulose base (H2) was developed on the basis of phase 1 results. That gel was buccally administered such that midazolam doses of 0.3 and 0.6 mg/kg were delivered. Each dog also received midazolam (0.3 mg/kg, IV). All posttreatment procedures were the same as those for phase 1. RESULTS The H1 and H2 formulations had lower viscosity, greater bioavailability, and peak plasma midazolam concentrations that were approximately 2-fold as high, compared with those for the P1 formulation. The mean peak plasma midazolam concentration for the H2 formulation was 187.0 and 106.3 ng/mL when the midazolam dose administered was 0.6 and 0.3 mg/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that buccal administration of gel formulations might be a viable alternative for midazolam administration to dogs.

MeSH terms

  • Administration, Buccal
  • Animals
  • Anticonvulsants / administration & dosage
  • Anticonvulsants / pharmacokinetics*
  • Area Under Curve
  • Biological Availability
  • Cross-Over Studies
  • Dogs / metabolism*
  • Female
  • Gels / administration & dosage
  • Gels / pharmacokinetics
  • Half-Life
  • Male
  • Midazolam / administration & dosage
  • Midazolam / pharmacokinetics*

Substances

  • Anticonvulsants
  • Gels
  • Midazolam