What is driving the recent price divergence between ampicillin and ampicillin sodium in China?

What is driving the recent price divergence between ampicillin and ampicillin sodium in China?
China's ampicillin market is showing a clear bifurcation. Bulk ampicillin base is under pressure, trading around RMB 271/kg in late July, down 0.6% month-on-month and 4.3% year-on-year, reflecting weak downstream veterinary and pharmaceutical demand. Ampicillin sodium, however, commands a wide premium range of RMB 352-410/kg depending on sterile versus non-sterile grade, though it too slipped 0.5% month-on-month and a sharper 12.1% year-on-year. The steeper annual decline for the sodium salt points to overcapacity in sterile injectable production. Meanwhile, the broader penicillin chain shows mixed signals: penicillin G potassium industrial salt is soft, but amoxicillin edged up to RMB 249/kg. This suggests buyers are favoring amoxicillin for oral formulations while ampicillin faces substitution pressure, especially in veterinary applications where cost sensitivity is high.