The resilience of the U.S. pharmaceutical supply chain has become a central concern for healthcare continuity, economic security, and public policy. Drug shortages expose a system in which manufacturing concentration, upstream dependencies, low-margin markets, incomplete supply-chain visibility, procurement incentives, and regulatory constraints can interact to convert localized disruptions into prolonged access problems. This narrative policy review critically examines the structural, economic, operational, and regulatory determinants of pharmaceutical supply vulnerability in the United States and evaluates the limitations of current policy responses. It argues that shortage management and supply-chain resilience are related but distinct objectives: the former is predominantly reactive, whereas the latter depends on the capacity to anticipate, absorb, adapt to, and recover from disruption. Building on this distinction, the review develops an integrated resilience architecture organized around eight functions: Detect, Assess, Incentivize, Diversify, Buffer, Adapt, Recover, and Learn. The framework links predictive supply-chain intelligence with resilience-oriented procurement, targeted manufacturing support, adaptive regulation, strategic capacity, and continuous learning. The central policy implication is that durable resilience requires coordination across regulatory, procurement, manufacturing, economic, and emergency-preparedness functions rather than a series of isolated shortage interventions. The paper therefore reframes pharmaceutical resilience as a designed property of market governance: one that must preserve safety, quality, affordability, and efficiency while reducing the probability that foreseeable vulnerabilities become prolonged national shortages.