My Easy Science
Dissolution Profile Comparison
Compare a test tablet's dissolution against a reference. The f2 similarity factor tells you if they match.
Inputs
Worked example
Worked example: reference 40, 60, 80, 90 and test 35, 55, 75, 85 at 10, 20, 30, 45 min gives f2 64.6 (similar) and f1 7.4.
Dissolution data
Edit the numbers in the table. Time in minutes, dissolved as a percentage of the label claim.
| Time (min) | Reference % | Test % | Remove row |
|---|
Variability (optional)
Enter the standard deviation (SD) for each point, or tick the box and enter the coefficient of variation (CV, %) instead. Used only to check the variability rule and to draw error bars.
| Time (min) | SD / CV reference | SD / CV test |
|---|
Dissolution profiles
| Value | Result |
|---|---|
| f2 similarity factor | — |
| f1 difference factor | — |
| Time points (n) | — |
| Mean squared difference | — |
| Verdict | — |
Similarity factor
— f2
Similarity factor f2. 50 or above means the profiles are similar.
Checked against hand-worked examples (see the page source comments).
Results are shown to 2 decimal places.
Rules checklist
- Not checked — At least 3 time points, excluding time zero.
- Not checked — Only one measurement after both products have reached 85% dissolved.
- Not checked — Variability: CV at most 20% at the earliest point and at most 10% at later points (only checked if SD or CV was entered).
Edit the table, then tap Show f2 and f1.
For learning only. Not for patient care decisions. Always check with a qualified professional and the product label.
How it works
When a generic tablet is compared with the original, regulators ask whether it dissolves the same way. Both are tested in the same apparatus, and the percentage dissolved is measured at the same time points. The similarity factor f2 turns the whole comparison into one number: it averages the squared differences between the two profiles, and 50 or above means similar. The difference factor f1 is the average absolute difference as a percentage of the reference, and 15 or below means similar.
The f2 rule only works when the comparison is fair: at least three time points, the same time points for both products, and only one time point where either product is above 85% dissolved, because once a tablet is nearly dissolved the numbers stop telling you anything. If the profiles are very different, f2 drops below 50, and the generic cannot claim to match the reference on dissolution alone.