Preparation, characterization, and pharmacokinetics in swine of a florfenicol enteric formulation prepared using hot-melt extrusion technology

Florfenicol sustained-release granules: an in vitro-in vivo correlation study in pigs

The objective of this study was to synthesize and characterize pharmaceutical characteristics of florfenicol sustained-release granules (FSRGs) in vitro and in vivo. FSRGs were synthesized using monostearate, polyethylene glycol 4000 and starch. In vitro dissolution profiles were studied using the rotating basket method in pH 1.2 HCl solution and pH 4.3 acetate buffer. Twenty-four male healthy Landrace×Yorkshire pigs were equally divided into three groups and administered a 20 mg/kg i.v bolus of florfenicol solution and dosed orally with FSRGs in the fasting and fed states. The Higuchi model was the best fit for the drug release profile in pH 1.2 and pH 4.3 media, and the mechanism of drug dissolution was governed by both diffusion and dissolution. We established a level A in vitro - in vivo correlation for FSRGs and the in vivo profile of the FSRGs can be estimated by the in vitro drug release.

Preparation, evaluation, and pharmacokinetics in beagle dogs of a taste-masked flunixin meglumine orally disintegrating tablet prepared using hot-melt extrusion technology and D-optimal mixture design

Flunixin meglumine (FM) is a nonsteroidal anti-inflammatory drug limited by irritation of the respiratory tract and mucosa in veterinary tissue. This study aimed to develop a taste-masked FM solid dispersion (SD) by hot-melt extrusion (HME) and formulate an orally disintegrating tablet (ODT) with selected excipients by direct compression. Eudragit® E PO was chosen as the matrix, and HME parameters were optimized: extrusion temperature, 135℃; screw speed, 100 rpm; and drug loading, 20%. Characterization techniques proved that FM was rendered amorphous in the HME extrudate. In vitro dissolution studies showed that FM SD released significantly slower than the corresponding physical mixture in artificial saliva. Excipients were selected based on compression formability, disintegration, and solubility. A D-optimal mixture design was used to optimize the composition: 25% FM SD, 18.75% microcrystalline cellulose, 52.5% mannitol, 3.75% low-substituted hydroxypropyl cellulose, and 1% magnesium stearate. Taste-masked FM ODT had a tensile strength of 0.7 ± 0.01 MPa and a disintegration time of 17.6 ± 0.1 s. E-tongue and E-nose analysis showed that FM ODT had a better taste-masked effect than commercial granules. Finally, a pharmacokinetic study proved that the main pharmacokinetic parameters of FM ODT were not significantly different from those of commercial granules, which indicated that these formulations had similar pharmacokinetic behaviours in beagles.

Preparation, characterization, and pharmacokinetics of tilmicosin taste-masked formulation via hot-melt extrusion technology

Tilmicosin (TMS) is a macrocyclic antibiotic specially used in veterinary clinics, but its extreme bitterness limits its use. This study aimed to obtain a taste-masked formulation of TMS by hot melt extrusion (HME) technology and to investigate the formulation's characterization, stability, and effects in vitro/in vivo. Eudragit® E PO was selected as the carrier, and TMS dissolution in artificial saliva was used as a reference. The HME parameters were optimized via an orthogonal design. The optimized results were as follows: 135 ℃ extrusion temperature, 100 rpm screw speed and 30 % drug load. The masking efficiency of the formulation was evaluated by both simulated oral drug release in vitro and electronic tongue tests. The release of the taste-masked formulation in artificial saliva medium was significantly reduced within 60 s (less than 2%), while the release in 0.1 M HCl buffer was fast (more than 80 %) within 30 min. As suggested by the results of the electronic tongue, the taste-masked formulation had a better taste-masked effect than the commercial premix and the commercial enteric granules. Finally, a pharmacokinetic study was performed. Analysis of variance demonstrated that the pharmacokinetic behavior of the TMS taste-masked formulation was similar to that of the commercial premix, while the absorption effect was better than that of the commercially available enteric granules. This research indicates that the taste-masked formulation has the potential for future commercialization.

Comparative muscle irritation and pharmacokinetics of florfenicol-hydroxypropyl-β-cyclodextrin inclusion complex freeze-dried powder injection and florfenicol commercial injection in beagle dogs

Florfenicol (FF) is a novel animal-specific amidohydrin broad-spectrum antibiotic. However, its aqueous solubility is extremely poor, far below the effective dose required for veterinary clinic. Thus, FF is often used in large doses, which significantly limits its preparation and application. To overcome these shortcomings, the FF-hydroxypropyl-β-cyclodextrin (FF-HP-β-CD) inclusion complexes were developed using the solution-stirring method. The physical properties of FF-HP-β-CD were characterized. A comparison was conducted between FF and FF-HP-β-CD freeze-dried powder injection of their muscle irritation and the pharmacokinetics. The drug loading and saturated solubility of FF-HP-β-CD at 37 °C were 11.78% ± 0.04% and 78.93 ± 0.42 mg/mL, respectively (35.4-fold compared with FF). Results of scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared showed that FF was entrapped in the inner cavity of HP-β-CD, and the inclusion complex formed in an amorphous state. In comparison with FF commercial injection, FF-HP-β-CD increased the elimination half-life (t_1/2β), transport rate constant (K₁₀, K₁₂, K₂₁), and maximum concentration (C_max) after intramuscular injection in beagle dogs. Conversely, it decreased the distribution half-life (t_1/2α), absorption rate constant (Ka), apparent volume of distribution (V1/F), and peak time (T_max). These results suggest that FF-HP-β-CD freeze-dried powder injection is a promising formulation for clinical application.