Suitability Of Amphen® Oral Suspension For Proportioners

Florfenicol is a broad-spectrum antimicrobial compound which exerts excellent activity against several bacteria, including Actinobacillus pleuropneumoniae and Pasteurella multocida. Typically, florfenicol is very lipophilic and demonstrates poor solubility in drinking water, resulting in sedimentation and crystallisation when used in proportioners. To overcome this, Huvepharma^® has launched Amphen^® 200 mg/ml florfenicol Oral Suspension.

This unique and innovative formulation is based on the nanonisation of florfenicol. Using this technology, poorly soluble florfenicol crystals are ground into many small nanoparticles (Figure 1). The subsequent increased surface area results in fast and complete dissolution of florfenicol. This feature increases florfenicol availability, and reduces the workload for the farmer due to fewer blockages in water delivery systems.

Figure 1. Nanonisation of florfenicol in Amphen^® Oral Suspension

In turn, stability in drinking water is crucial. A high florfenicol availability contributes to an optimal clinical outcome as the active compound should reach the target tissues in the animal at the optimal concentration. The suitability of Amphen^® Oral Suspension for therapeutic use in proportioners was evaluated.

1. Visual appearance

The visual appearance of mixtures with eight different liquid veterinary products containing florfenicol was evaluated for their therapeutic use in proportioners. 

• Trial description
  • Products tested:
    • Amphen® Oral Suspension
    • Seven other liquid products containing florfenicol (six products: 100 mg/ml, product number 5: 200 mg/ml)
  • Two qualities of drinking water: hard water at pH 8.04 and soft water at pH 6.12
  • Florfenicol inclusion level: 100 g florfenicol, corresponding to 500 ml Amphen^® Oral Suspension per 10 l stock solution
  • Mixtures were stirred for 10 seconds
  • Time points: 0, 12 and 24 hours
• Results
  • Amphen® Oral Suspension: Perfect homogenous suspension at all three time points (Figure 2)
  • Other products: Massive sedimentation of insoluble florfenicol crystals at the bottom of the recipient immediately after administration and further precipitation over time (Figure 3)

Figure 2. Pictures of the Amphen^® Oral Suspension beaker after 0, 12 and 24 hours*

Figure 3. Pictures of beakers containing other liquid florfenicol products immediately after administration*

* Visual appearance was independent of the use in hard or soft water. Figures 2 and 3 show beakers using hard water

2. Stability

The recovery of florfenicol at nipple level when using Amphen® Oral Suspension was evaluated during a 24-hour study.

• Trial description
  • One litre of Amphen® Oral Suspension in 20 litres of water (pH 7.0) in a stock container
  • The suspension in the stock container was stirred manually for 10 seconds. An automatic stirring device was not installed
  • The proportioner was set at a 1:100 injection rate
  • Samples at nipple level were taken at 0, 6, 12 and 24 hours
  • Florfenicol concentration was determined by a validated HPLC method and expressed as a percentage of the theoretical concentration
• Results are shown in Figure 4

Figure 4. Florfenicol recovery expressed as a percentage of the theoretical concentration at nipple level using a proportioner set at 1%

Summary

Amphen® Oral Suspension demonstrates excellent solubility in drinking water, facilitating use in proportioners, even at a setting of 1%. In addition, excellent recovery of florfenicol at nipple level was demonstrated over 24 hours.