Intermixing of blister strips refers to the unintended presence of blister packs containing tablets or capsules of a different product, strength, or batch within the same carton, shipper, or lot. This is a critical quality defect that can occur at any point in the packaging process and represents a serious breach of Good Manufacturing Practice (GMP) requirements.
The pharmaceutical packaging area often handles multiple products with similar packaging materials, which increases the risk of cross-contamination and intermixing. Potential scenarios include:
- Residual blister strips from a previous batch or product left behind in packaging lines, accumulation hoppers, conveyors, or packing tables due to inadequate line clearance.
- Human error during product changeovers, such as failure to remove in-process materials, labels, or printed cartons before starting the next batch.
- Inadequate segregation of rejected, reworked, or sampled blisters from conforming product.
- Visual similarity between blister strips or labels that can lead to mix-ups, especially under time pressure.
- Uncontrolled return or reintroduction of previously removed or quarantined packs without proper verification.
Intermixing of blister strips has severe consequences, including:
- Potential administration of incorrect medication or dosage to patients, leading to lack of efficacy or adverse reactions.
- Loss of product traceability and breach of product identification requirements.
- Regulatory action, such as product recalls, warning letters, and loss of market authorization.
- Damage to company reputation and loss of customer trust.
Given the high risk associated with this defect, pharmaceutical manufacturers must implement robust preventive and detection controls, including:
- Comprehensive line clearance procedures and documented verification of equipment and work areas before batch start-up.
- Physical and procedural segregation of materials during all stages of processing.
- Effective reconciliation of packaging components and finished product quantities.
- Independent line checks and in-process monitoring by trained personnel.
- Automated vision inspection systems to detect foreign or mismatched blisters.
- Clear labeling, color coding, and differentiation strategies to minimize confusion.
