Doxycycline API production is concentrated in a small number of manufacturing facilities, primarily in Asia, meaning that a single facility shutdown, regulatory action, or surge in demand can rapidly tighten global supply. US importers have responded by qualifying multiple suppliers across different facilities, maintaining larger safety stocks, and monitoring FDA import alert databases for any enforcement actions against key manufacturers. Diversifying the approved supplier list before a shortage occurs is the most effective mitigation strategy.

Tetracyclines intended for human pharmaceutical use must be imported from FDA-registered drug establishments and are subject to drug cGMP requirements. Those intended as veterinary feed additives are regulated under FDA's animal food program administered by the Center for Veterinary Medicine, with different facility registration and labeling requirements. Mixing up these pathways — for example, importing a feed-grade product under a pharmaceutical entry — can result in detention or refusal, so the intended use must be clearly declared on entry documentation.