PUB-002 / v2.0
Ten potential compounding failure mechanisms
This review considers ten potential mechanisms. It does not rank them by frequency because no incident dataset with a denominator supports such a ranking.
Compatibility of the final matrix
Mechanical mixing does not establish solubility, uniformity or chemical compatibility. Assess pH, crystallisation tendency, emulsion structure and preservative partitioning. A concentration stated for the original base may change after dilution. The two starting products’ expiry dates do not establish the mixture’s lifetime.
Tests that answer the question
Appearance identifies some failures but does not establish strength, absence of degradants or microbiological suitability. Select method and criterion for the actual dosage form and use. A suspension needs redispersibility and device-delivered-dose assessment; at low strength, uniform mass does not imply uniform API. A critical specification failure requires quarantine and investigation.
Patient staff and contamination
Assess clinical risk, staff exposure and residue carryover into the next task separately. Quantity, frequency, dust/vapour generation and containment influence the decision. Use the exact material’s current SDS and an appropriate active-drug source. Absence from a hazardous-drug list does not mean absence of hazard.
Safe handover and learning
Handover links the correct patient, preparation, strength, route and dosing device. Assess understanding through demonstration and teach-back. Investigate complaints or failures using evidence rather than automatically assigning one mechanism. CAPA includes an owner, deadline and effectiveness check so the finding produces a concrete improvement.
Ten investigation points
1. Identity/chemical form. 2. Units/calculation. 3. Solubility/dispersion. 4. pH shift. 5. Emulsion/gel structure. 6. Preservation. 7. Dose nonuniformity. 8. Packaging/withdrawal. 9. Incompatible storage or unsupported BUD. 10. Order, labelling or traceability error. Order is educational.
Six pre-compounding questions
What is the confirmed need? Which pH and matrix are supported? How is dissolution or uniform dispersion achieved? Which microbiological protection is needed? Which container and device support correct withdrawal? What evidence permits compounding and dating? Each negative or unknown answer needs a defined action.
Sources and references
- PIC/S — Guide to Good Practices for the Preparation of Medicinal Products in Healthcare EstablishmentsPE 010-4, 1 March 2014Chapters 1–9; Annex 2 (nonsterile liquids, creams, ointments)Professional quality-system framework; not automatic national legal adoption or certification2026-09-12
- NAPRA — Model Standards for Pharmacy Compounding of Non-sterile PreparationsMarch 2018, clarification January 2022Sections 4–9Risk, personnel, facilities and QA; its historical BUD table is not used for current USP defaults2026-09-12
- NIOSH — Managing Hazardous Drug Exposures: Information for Healthcare SettingsDHHS (NIOSH) 2023-130Risk assessment and activity-specific control table, printed pp. 27–33Exposure routes and hierarchy of occupational controls2026-09-12