Why aren't all oral drugs made sweet with aspartame?

Why aren't all oral drugs made sweet with aspartame?
Aspartame's role in pharmaceuticals is narrower than its food use suggests. In tablet formulation, sweeteners are auxiliary, not core excipients. Standard tablet ingredients—fillers, binders, disintegrants, lubricants—are chosen for processability and stability, not taste. Sugar powder, a natural sweetener, is limited to under 20% due to hygroscopicity that harms storage and tableting. Stevioside, 200–350 times sweeter than sucrose, is used at 0.025–0.05% but adds bitterness and moisture uptake. Aspartame, a synthetic peptide sweetener, offers high sweetness with low dose, yet its use in oral solids remains limited because taste masking is secondary to drug release and stability. For liquid suspensions or chewables, aspartame finds more application, but formulators must balance sweetness against degradation, especially at low pH or high temperature. The pharmaceutical grade market is niche, with key producers like Ajinomoto and HYET Sweet, and China-based suppliers such as Jiangsu Hanguang and Changzhou Guanghui serving this specialized segment.