MACO
Maximum Allowable Carryover
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
MACO is the maximum quantity of a residue from a previous product that may be carried over into the next product without posing a safety risk to the patient. It is the numerical acceptance limit that a cleaning validation must demonstrate the equipment falls below.
The health-based MACO derives from the PDE of the previous product, the batch size and maximum daily dose of the next product: conceptually MACO = (PDE_previous × minimum batch size_next) ÷ maximum daily dose_next. This total-carryover figure is then divided by the shared surface area to give a limit per square centimetre that the swab result can be measured against.
Historically MACO was also computed from the 1/1000th-of-minimum-therapeutic-dose criterion and the 10 ppm criterion; current guidance treats the health-based value as primary and the others as additional checks, taking the most conservative where appropriate.
- —Health-based MACO is derived from the previous product PDE.
- —Converted to a per-surface-area limit (µg/cm²) for swab comparison.
- —Dose-based and 10 ppm limits are secondary cross-checks.
- —Choose the most conservative defensible limit.
EMA health-based exposure limit guideline (EMA/CHMP/CVMP/SWP/169430/2012); APIC Guidance on Aspects of Cleaning Validation for the MACO formula conventions.
Frequently asked questions
What does MACO stand for?
MACO stands for Maximum Allowable Carryover.
What is MACO?
MACO is the maximum quantity of a residue from a previous product that may be carried over into the next product without posing a safety risk to the patient. It is the numerical acceptance limit that a cleaning validation must demonstrate the equipment falls below.
Which regulations cover MACO?
EMA health-based exposure limit guideline (EMA/CHMP/CVMP/SWP/169430/2012); APIC Guidance on Aspects of Cleaning Validation for the MACO formula conventions.