Enhancing Palatability in a Dual-API Oral Formulation for Canine Health

Palatability is a critical factor in the development of oral veterinary formulations, especially for companion animals such as canines. Beyond therapeutic efficacy and stability, successful formulations must ensure voluntary intake and compliance during treatment.

Aragen  developed a dual-API chewable tablet (API-A and API-B) for canine administration, across three dosage strengths. Both APIs exhibited intense bitterness and unpleasant mouthfeel, resulting in poor voluntary intake (~45% acceptance) and inconsistent dosing during in vivo palatability studies. The initial prototype also faced challenges with flavor–excipient incompatibility, moisture sensitivity leading to texture softening, and content uniformity issues.

To address these challenges, the team applied a systematic formulation design strategy—integrating taste masking, excipient compatibility screening, and process optimization—to create a stable, palatable, and manufacturable chewable tablet suitable for canine use.

The initial chewable tablet, intended for once-daily dosing in medium-sized canines, demonstrated therapeutic efficacy but poor sensory performance. The following key challenges were identified:

• Intense bitterness of both APIs (weakly basic, highly soluble compounds).
• Chemical incompatibility with natural/synthetic flavors led to aroma loss and potential degradation.
• Moisture sensitivity caused texture softening, compromising chewability and shelf life.
• Content uniformity variability resulted in inconsistent dosing and reduced reliability.

These factors collectively compromised the sensory profile, physical stability, and reproducibility of the final product, as summarized in Table 1.

Table 1. Key development challenges

Aragen’s formulation development team employed an integrated development strategy involving taste masking, excipient compatibility testing, and process optimization.

1. Pre-formulation & Compatibility Screening

• The excipient compatibility was addressed using screening of around 8-10 natural, synthetic and combination flavours. Evaluated potential interactions between APIs and excipient bulk with the flavoring agents through degradation profiling and appearance testing.
• Identified two compatible natural flavors (Flavor 1 at 8 % w/w and Flavor 2 at 6% w/w).
• Selected a synthetic flavor blend (containing maltol and vanillin) for its stability and aroma retention under accelerated conditions.

2. Palatability Optimization

A comprehensive palatability enhancement study was conducted to explore optimal combinations of natural flavor components  (1 & 2) and synthetic flavor enhancers.

• Designed 12 trial formulations (F1–F12) with varying levels of natural flavor 1 (2–8%), natural flavor 2 (1–6%), and synthetic flavor enhancers (0.1–0.5%), tested both individually and in combination.
• Client conducted two-stage in vivo palatability screening in adult beagle canines using voluntary intake scoring (complete, partial, or refusal).
• Optimized trial formulation F10 achieved the most favorable sensory response.

3. Composition and Process Optimization

• Incorporated API-A via wet granulation within a stabilizing excipient matrix; API-B blended post-drying to prevent degradation.
• Optimized binder (PVP K-30 at 3.5% w/w) and milling aperture to ensure uniform distribution of flavoring and masking agents.
• Introduced 5% glycerol and 3% sorbitol to improve chewability and texture stability.

The optimized chewable tablet (F10) demonstrated substantial improvements in palatability, uniformity, aroma masking, and stability (Table 2).

Table 2: Study outcomes

The formulation displayed excellent chewable texture (hardness 25–30 N) and mechanical integrity (friability <0.3%). Scale-up from 2 kg lab batches to 20 kg pilot batches at the client facility verified robust process reproducibility and blend homogeneity (RSD < 2%) with no flow or segregation issues. Figure 1 captures the palatability improvement in terms of canine voluntary intake studies.

Figure 1. Comparative palatability improvements across formulations (F1–F12), with F10 achieving 85% voluntary intake. Bars represent mean values ± standard deviation. Asterisks indicate significance levels: p < 0.10 (*), p < 0.05 (**), p < 0.01 (***) vs F1.

The optimized chewable formulation:

• Achieved 85% voluntary intake in canine palatability trials, surpassing target performance.
• Enabled once-daily dosing combining two therapeutic benefits in a single tablet.
• Supported product development document  through proven stability and scalability.

Through a strategic blend of formulation design and sensory assessment, Aragen successfully developed a stable, scalable, and  palatable dual-API chewable tablet for canine health. This achievement highlights Aragen’s expertise in creating innovative, animal-focused solutions that seamlessly integrate scientific precision with enhanced sensory acceptance.

At Aragen, we integrate pharmaceutical science, sensory design, and process excellence to develop animal health formulations from that combine efficacy with high acceptability. Our capabilities include:

• End-to-end veterinary formulation development for solid, semi-solid, parenteral, and liquid dosage forms.
• Taste masking and palatability optimization using advanced encapsulation and coating technologies.
• Comprehensive analytical support, including stability and flavor retention profiling.
• Seamless technology transfer from concept to pilot-scale manufacturing.

Whether your goal is to improve product acceptance, enhance compliance, or strengthen formulation robustness, Aragen offers science-driven that accelerate the success of your animal health products—efficiently and effectively.