// multi-utility computation suite · offline · instant · precise
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sci.henderson-hasselbalch-drug Calculator
Calculates ionisation fraction and membrane permeability of a drug from pKa and Henderson-Hasselbalch at physiological pH. Acidic drugs (aspirin pKa 3.5): < 0.01% unionised at pH 7.4 — despite this, lipophilicity drives membrane partitioning; the pH-partition hypothesis assumes only unionised drug permeates.
Inputs
Pka
Reference formula or conversion factor shown for context.
Ph Biologic
Reference formula or conversion factor shown for context.
Is Acid
Reference formula or conversion factor shown for context.
Results
ionised fraction at pH 7.4
pH of the solution. Below 7: acidic. 7: neutral. Above 7: basic (alkaline).
un-ionised (membrane-permeable) fraction
Sample size or count used in the calculation.
[ionised]/[unionised] ratio
The proportional relationship between two quantities.
Henderson-Hasselbalch
Sample size or count used in the calculation.
drug type
The classification or type assigned based on the inputs.
absorption note
Supplementary information explaining an assumption, caveat, or important context for interpreting the result.