LabreadorLabreador / Bioassay analysis
Relative Potency Calculator
Estimate the horizontal shift between a reference and test preparation with Labreador's Parallel Line Analysis. The full module fits a constrained model and checks parallelism before you interpret relative potency.
Free · No account · Local web calculations · Research use only
Worked example
If a justified parallel 4PL fit gives C_reference = 16 and C_test = 20 in the same concentration unit, RP = 0.8 and RP% = 80%. This ratio illustration does not calculate a fit, confidence interval or parallelism verdict. Use the full module to analyse reference and test responses.
Equation and units
RP = C_reference / C_test RP (%) = 100 * C_reference / C_test
Full analysis workflow
- Paste reference and test concentration-response data with one replicate per row.
- Choose 4PL or 5PL and a justified weighting model.
- Inspect constrained versus independent fits, parallelism, residual variance and lack of fit where replicates permit it.
- Report RP% with its uncertainty and assay acceptance criteria; combine independent runs only with the relevant diagnostics.
Interpretation and limitations
A ratio of separately fitted midpoints does not establish parallelism. Non-significant differences do not prove equivalence. Labreador uses methods informed by Ph. Eur. 5.3 and USP bioassay guidance; a result is not a regulatory certificate or a replacement for product-specific validation. Unbounded or unavailable confidence intervals must not be interpreted as narrow, reliable estimates.
Common questions
- Can I calculate relative potency online for free?
- Yes. Labreador's PLA module jointly fits reference and test 4PL or 5PL curves with shared shape parameters and separate concentration parameters, then reports relative potency and diagnostics without a paid licence.
- Which confidence intervals does Labreador report for potency?
- The PLA module reports a 500-iteration residual-bootstrap interval and a Fieller interval when available. The method and interval limitations should accompany the point estimate.
- Does the calculator prove pharmacopoeial compliance?
- No. The implemented methods are informed by pharmacopoeial bioassay guidance, but study design, equivalence limits, validation and regulated use remain the analyst's responsibility.