Volume-based drug procurement and pharmaceutical firms’ R&D intensity: evidence from Chinese a-share listed manufacturers

China’s national volume-based drug procurement (VBP) policy aims to reduce drug prices, ease pressure on medical insurance funds, and standardize distribution. This study evaluates the association between direct VBP selection and pharmaceutical manufacturers’ R&D intensity, contributing to understanding of behavioral responses to cost-containment policies. Using panel data for 293 A-share listed pharmaceutical manufacturing firms from 2015 to 2023, policy exposure was identified from the policy year assigned to a firm’s first nationally VBP-selected batch. A staggered difference-in-differences design using Callaway–Sant’Anna estimates assessed the association with R&D intensity. Event-study, pretreatment joint tests, alternative dependent variables, and sample-composition checks evaluated credibility. Heterogeneity and marketing-dependence analyses used pooled interactions by ownership type, regional marketization, and pre-policy marketing dependence. (1) Direct VBP selection was associated with higher R&D intensity (ATT = 0.03679; 95% CI 0.00340–0.07018; p = 0.0308). The group-time pretreatment test did not reject at 5% ( p = 0.1004), but the aggregated-event test did ( p = 0.0169). (2) Supplementary tests showed an approximately zero estimate using R&D expenditure scaled by total assets, but negative estimates for log R&D expenditure and log revenue. Personnel outcomes did not corroborate input expansion. (3) Formal interactions did not establish differences by ownership, regional marketization, or pre-policy marketing dependence. The intensity estimate attenuated under upper-tail compression and control-group completeness restrictions. VBP may be interpreted as both a cost-containment instrument and an institutional reform that could reshape pharmaceutical market competition. Higher intensity does not establish increased research inputs or active reprioritization; pretreatment departures and sample sensitivity constrain causal attribution. Future procurement policy should balance price reduction with quality assurance, stable supply, and innovation incentives.