Predicting Drug-Loading Limits In Tablet Formulations

If you're formulating high-dose tablets, you've probably hit the point where the active pharmaceutical ingredient (API) starts working against you. Poor flowability, lamination risk, capping defects: these aren't random occurrences. They signal that your drug load has crossed a critical threshold, and if you don't know where that threshold sits, you're running experiments to find it the hard way.

This case study applies the OSD Predict toolbox alongside Heckel analysis and compaction behavior evaluation to binary blends of crystalline API and spray-dried dispersion (SDD) with Avicel PH-102. Both forms exhibited low bulk density and cohesive powder behavior. Heckel analysis flagged limited bonding capacity and moderate strain-rate sensitivity, two indicators of compression risk that often get overlooked in early development.

Using a power-law model to map how particle size, morphology, and API-to-excipient ratios affect blend behavior, the analysis pinpointed critical percolation thresholds at approximately 20% drug load for the crystalline API and 15% for the SDD form. Above these concentrations, API behavior dominates the blend and tabletability deteriorates.

Knowing these limits upfront changes how you design your formulation strategy. Download the full case study to see how predictive percolation modeling reduces experimental burden during tablet development.