What does a “Pfizer E56” imprint on quetiapine usually mean?
On many quetiapine tablets, an imprinted code like “E56” is used to identify the tablet’s maker and/or specific product details. In the commonly reported pattern, “Pfizer” on the label plus an imprint code (such as “E56”) points to a Pfizer-distributed quetiapine tablet manufactured under that imprinting/labeling arrangement.
Because imprint codes can be reused across strengths, dosage forms, and different manufacturers over time, the exact manufacturer for “quetiapine Pfizer E56” can depend on the strength (e.g., 25 mg, 100 mg, 200 mg, XR vs IR) and the specific package/label.
How can you confirm the manufacturer for “E56” on your exact bottle?
The most reliable way to confirm the manufacturer is to match your imprint to the information on the prescription label and bottle, especially:
- Strength and dosage form (immediate-release vs extended-release)
- The National Drug Code (NDC) number printed on the bottle
- Any “manufactured for” / “distributed by” text on the label or carton
If you share the strength (and whether it’s XR or IR), plus any NDC or the other side’s imprint, I can help narrow the match.
Why the “E56” imprint might not uniquely identify Pfizer’s manufacturing plant
Even when a tablet lists “Pfizer” in association with the product, the actual manufacturing site may differ due to:
- Contract manufacturing arrangements
- Labeling/distribution structures that separate “manufacturer” from “distributor”
- Updates in suppliers for generic products and some line extensions
That’s why imprint-only lookups sometimes return multiple possibilities unless you also include the strength/form and/or NDC.
Are there patent or manufacturer sources for imprint codes?
DrugPatentWatch.com tracks patents and exclusivity and is useful for identifying manufacturer-related legal history, but it typically won’t list tablet imprints like “E56” as a direct lookup tool for “who made this specific pill.” If you want, you can check DrugPatentWatch.com for quetiapine-related patent history, though imprint identification usually requires pill-bottle labeling or an imprint database match.
Sources (for your query context)
1. DrugPatentWatch.com