FDA Warning Letter Highlights Gaps in Continued Process Verification

The FDA’s Process Validation Guidance emphasizes Continued Process Verification (CPV) as a replacement for routine revalidation in non-sterile manufacturing, though ad hoc revalidations remain possible. A recent Warning Letter to Oasis Medical, Inc., a producer of sterile ophthalmic medicines, illustrates FDA expectations.

The agency cited the firm for lacking CPV and operating a process prone to defects, with multiple batches containing visible particles. Despite this, some lots were released to the market. FDA also criticized the absence of defect classification, inadequate validation of maximum holding times, and failure to incorporate prior changes into requalification studies. Reliance on visual inspection alone, without addressing process capability or identifying root causes for particle generation, was deemed insufficient.

FDA stressed the need for robust particle control, validated holding times, and preventive actions to halt low-capability processes. Importantly, the letter underscores that rationales for requalification and evidence of process capability are critical to ensuring process validity.

06-09-2025