Amphastar Pharmaceuticals' stock experienced a significant after-hours plunge of 16.73% following the release of its first-quarter financial results.

The company reported quarterly results that fell short of analyst expectations. Revenue was essentially flat year-over-year at $171.2 million, missing the consensus estimate. More notably, adjusted earnings per share came in at $0.42, significantly below the estimated $0.70 to $0.71, while GAAP net income plummeted 75% to $6.4 million.

The disappointing performance was driven by lower average selling prices for key products including BAQSIMI, glucagon, phytonadione, and epinephrine, which reduced gross margin. Additionally, higher manufacturing expenses from facility expansion and increased research & development costs, including a $2 million licensing payment, further pressured profitability.