Bacterial Endotoxin Limit Calculator
Calculate the bacterial endotoxin limit for a parenteral product from the threshold pyrogenic dose and the maximum human dose per kg per hour — limit = K / M, with K = 5.0 EU/kg (0.2 EU/kg intrathecal). Aligned to USP <85> and Ph. Eur. 2.6.14.
OUTPUT
TIME
Limitations — read before you rely on this
- The formula depends entirely on correctly determining M (the maximum dose per kg per hour) from the label; an ambiguous or weight-independent dose needs the compendial special-case conventions this tool does not implement.
- Product-specific monograph limits and radiopharmaceutical or device conventions override the general K/M result; always check for a governing monograph first.
- This calculator is transparent but it is not a validated system, and it does not perform the assay, interference testing, or method suitability.
- Reproduce the limit in your own qualified system and confirm it against the current compendial chapter before it enters a release specification.
WHAT THIS CALCULATES
Calculates the bacterial endotoxin limit for a parenteral product from the applicable threshold pyrogenic dose and the maximum human dose per kilogram per hour.
THE METHOD
Limit = K / M- Limit
- The maximum permitted endotoxin concentration, in EU per dose unit (EU/mL, EU/mg, or EU/Unit — matching how M is expressed).
- K
- The threshold pyrogenic dose per kg per hour: 5.0 EU/kg for parenteral routes other than intrathecal, 0.2 EU/kg for intrathecal.
- M
- The maximum recommended human dose per kilogram of body weight administered in a single one-hour period, in the same unit the limit is expressed in.
Express the limit in the same dose unit as M — get the unit of M wrong and the limit’s unit follows. The maximum valid dilution (MVD = Limit ÷ lysate sensitivity λ) is a downstream method-suitability step this tool does not compute. Specific USP/Ph. Eur. monograph limits override the calculated value.
THE INPUTS, AND WHAT THEY MEAN
- Route (threshold dose K)
- The administration route that sets K: 5.0 EU/kg for non-intrathecal parenterals, 0.2 EU/kg for intrathecal — a 25× stricter limit for the same dose per kg.
- Maximum dose per kg per hour (M)
- The largest dose of product given per kilogram of body weight within one hour at the maximum label dose, in mL/kg, mg/kg, or Units/kg to match the desired limit unit.
- Measured endotoxin (optional)
- The analytically determined endotoxin content in the same dose unit, to compare against the calculated limit. Leave blank to compute the limit only.
Endotoxin limit from the maximum dose.
Choose the route, then enter the maximum recommended dose per kg per hour (M). SPEQ applies the threshold pyrogenic dose K — 5.0 EU/kg for parenteral, 0.2 EU/kg for intrathecal — to compute the endotoxin limit K/M.
HOW TO READ THE OUTPUT
- The endotoxin limit is a specification ceiling set by the compendia; the 5.0 and 0.2 EU/kg thresholds are USP/Ph. Eur. values, not SPEQ’s, and they are route-driven — the intrathecal limit is 25× stricter.
- Expressing the limit requires matching units: if M is in mL/kg/hr the limit is EU/mL; getting the unit of M wrong is the dominant error, not the division itself.
- Where a USP/Ph. Eur. monograph states an explicit endotoxin limit for the product, that value governs and this calculation is only a cross-check.
- A limit computed here still needs a bacterial-endotoxins test whose maximum valid dilution reaches it; if interference forces more dilution, the method needs a more sensitive reagent.
WORKED EXAMPLE
Setting the endotoxin limit for an IV drug whose maximum dose is 10 mg/kg administered in one hour.
- Route (K)
- parenteral, 5.0 EU/kg
- M
- 10 mg/kg/hr
RESULT
Every batch must test at or below 0.5 EU/mg; the bacterial-endotoxins method must reach that limit within its maximum valid dilution, or a more sensitive lysate is required.
REGULATORY BASIS
- USP <85> Bacterial Endotoxins Test
- Defines the endotoxin-limit formula (K/M), the threshold pyrogenic doses, and the maximum valid dilution.
- Ph. Eur. 2.6.14 Bacterial Endotoxins
- The European compendial counterpart specifying the same limit and test conventions.