Blockchain Traceability Architecture Choice in Cross-Border Pharmaceutical Supply Chains: Robust Optimization and Break-Even Conditions

Abstract

Cross-border pharmaceutical supply chains must choose a traceability architecture while coordinating procurement, production, bonded-warehouse inventory, customs execution, and fulfilment under uncertain demand. Existing blockchain assessments often compare predetermined scenarios without showing which operational mechanism creates the apparent cost advantage or when the ranking reverses. This study formulates a multi-period robust linear program that compares no-blockchain, basic, enhanced, and hybrid on/off-chain architectures through operating expenditure, blockchain cost, five avoidable loss channels, and monetized residual risk. The analysis provides a componentwise architecture-cost comparison, an exact fixed-service savings decomposition, and an ordered-block characterization of joint-budget uncertainty protection. In an anonymized pharmaceutical case calibrated with public proxies, expert-derived analytic hierarchy process weights, and 2021–2023 trade observations, enhanced traceability reduces total cost from 9.455 to 8.968 million United States dollars (USD) and the risk index from 1928.73 to 1314.18. Of the 0.487 million USD saving, 85.24% is associated with the smaller fulfilment-side planning buffer; a 71.9 thousand USD advantage remains when all architectures satisfy the same service requirement. Direct shipment is shown to be capacity-triggered by the saturated inbound-to-warehouse link of the second manufacturer (M2) rather than by route-cost arbitrage. Enhanced traceability remains least costly in the 2024 held-out test, while break-even analysis identifies distinct implementation-cost and benefit-realization regions for enhanced, hybrid, and no-blockchain operation. A three-segment joint-budget extension restores a meaningful role for the uncertainty budget over $\Gamma \in [{0,3}]$ . The resulting framework converts blockchain adoption into a conditional architecture-choice problem governed by traceability benefits, implementation cost, service protection, and physical capacity.