Dissolution Time Points by Dosage Form — Sampling Schedule & % Release Guide

When you pick a dosage form, the calculator builds one panel for each time point in its starting schedule. These are presets to save typing, not a substitute for your monograph or SOP. Edit the time in any panel, delete the ones you do not need, or add your own.

The thinking behind the schedules is simple. Immediate-release forms are expected to dissolve quickly, so samples are taken often in the first hour. ODTs and chewables are shorter still. Sustained, extended and controlled-release products are designed to release over many hours, so the samples are spread across the intended dosing interval, up to 24 hours for ER and CR. When your protocol needs points beyond 24 hours, the time boxes accept up to 72 h, so you can add panels past the preset.

The tool also shows a hint under the dosage form menu, for example "Rapid-release — sampling every 5–15 min up to 60 min" for IR tablets, so you can confirm you picked the right preset before you enter any data.

An enteric coating is meant to keep the drug from releasing in the stomach and let it release in the intestine, so the test has two parts, and the calculator treats them as two separate runs. There is no combined option.

• After selecting an enteric-coated form, a required Select Test Phase drop-down appears and no time-point panels are shown until you choose one.
• Changing the phase clears the panels and any results, so record one phase, copy or print it, then switch to the other.
• A small Acid Phase or Buffer Phase badge appears on the result card, and the same wording is used in the copy text and on the printed report.
• To judge the acid phase against a limit from your monograph, type that limit in the Max Limit box of the 2 h panel.

Once you pick a dosage form, a System Configuration & Constants section appears. Its values are shared by every time point, so you fill them in once.

With or without a Covering Standard

The default is Without Covering Standard: every time point uses the System Suitability mean. With Covering Standard adds a covering readings block to each time point panel, with two rows to start. For that time point the standard becomes the average of two numbers: the System Suitability mean and that panel's covering mean. A line in the block says No Covering readings entered yet until you add values, and in that case the System Suitability mean is used alone. Covering readings of one time point never affect another.

The formula is the same one used by the main Dissolution Calculator:

Sample Response is the peak area or absorbance of the vessel. Final Std is the System Suitability mean, or the averaged value described above when covering readings are present. The printed report writes the same formula and leaves out the API Factor when you did not use one. For a closer look at the terms and a worked example, see the Dissolution Calculator guide.

For each time point the calculator then works out the mean of the vessels, the SD (dividing by n − 1), the %RSD (SD ÷ mean × 100), and the minimum and maximum vessel.

• Time Point. Hours and minutes boxes, so 1 h 30 min is typed as 1 and 30. The title updates to read, for example, 90 min, 2 h or 1 h 30 min.
• Min Limit (%) and Max Limit (%). Optional acceptance limits for that time point only, each from 0 to 200.
• Vessels. Six rows to start. Add Vessel adds a row and × removes one. A line shows how many vessels the panel has. Empty rows are ignored and at least one valid reading is needed.
• Calculate This Time Point. Each panel is calculated on its own, with its own button and its own result card underneath. There is no single button that calculates all panels together.
• Reset on a panel clears only that panel's vessel readings. Remove deletes the panel, and at least one panel must remain.
• Add Time Point adds a blank panel with six vessels at the bottom, for any time your protocol needs.

Changing a panel's time or editing its vessel readings hides that panel's result. Changing the instrument type or the absorbance range hides every result. The Reset button at the bottom of the page clears the whole form, including the dosage form and all constants.

This calculator checks limits, not stages. There is no Q value and no S1, S2 or S3 here. For that kind of test, use the Dissolution Calculator, which counts vessels and applies stage rules. In this calculator the rules are:

Two things follow from this. First, the verdict uses the mean, so a time point can pass even when an individual vessel is flagged. Second, the %RSD is shown but does not affect the verdict, so judge it against your own SOP.

Dosage form: Sustained-Release (SR) Tablet, HPLC, no covering standard. Standard weight 20.0 mg, potency 99.5%, dilution factor 10, label claim 200 mg, medium volume 900 mL, no API factor. Five standard injections: 502100, 503400, 501800, 502900 and 502300.

Final Std = 502500 (the mean). SD = 644.20 and %RSD = 0.13%. In the 2 h panel, set Min Limit to 40 and Max Limit to 50, then enter six vessels:

For vessel 1: (227800 × 10 × 0.995 × 20.0 × 100) ÷ (502500 × 200) = 45.11%. The result card shows Mean 45.13%, %RSD 2.13%, Min 43.52%, Max 46.16%, SD 0.96 and 6 vessels analyzed. The mean sits between 40 and 50, so the verdict is Pass.

Changing the limit

Raise the Min Limit to 44 and calculate again. Vessel 5 (43.52%) now shows a red Fail in its row, but the time point still passes, because the mean of 45.13% is above 44. Raise the Min Limit to 46 and the mean itself falls short, so the verdict becomes Fail. Clear both limit boxes and the card shows Pass with No limits set — showing calculated % Release only.

• Six figures: Mean % Release, %RSD, Min % Release, Max % Release, Vessels Analyzed and SD.
• Verdict tag and, when limits were set, a note such as Limits: Min 40.0% | Max 50.0%.
• Dosage form badge next to the heading, plus the Acid Phase or Buffer Phase badge for enteric-coated forms.
• A short summary paragraph that states the dosage form, time point, number of vessels, mean, %RSD, min, max and, if limits exist, the verdict in words.
• Per-vessel flags in the vessel rows themselves, showing each % release and a Pass or Fail mark.

Each calculated time point is stored, and the copy and print buttons include every time point you have calculated, in the order the panels appear.

Both buttons need at least one calculated time point. If none exists, a message asks you to click Calculate on a time-point panel first.

Copy Report copies a plain-text summary: the dosage form, then for each time point every vessel's reading and % release, the mean, SD, %RSD, min and max, and the result. The button shows Copied! for a moment.

Print Report opens an editable A4 sheet. These fields are filled automatically and locked, so the sheet matches what was entered: dosage form, standard potency, standard weight, dilution factor, medium volume and label claim. The System Suitability table (readings, average, SD and %RSD) and the formula are filled in as well, followed by one table for each calculated time point with a PASS or FAIL line. You type the batch number, dates, instrument and the rest directly on the sheet. The sheet can run to more than one page, with the letterhead and signature block repeating.

Because the sheet is built from stored results, the locked fields show whatever is in the form at the moment you open it. If you changed a standard weight or potency after calculating, recalculate before printing.

A logo must be a PNG, JPG or WebP image that is perfectly square, between 30 × 30 and 1000 × 1000 px, and no larger than 1 MB. Rectangular logos are rejected. Choose Save as PDF in the print dialog and switch off Headers and footers for a clean file.

• Treating the preset as the specification. The loaded time points are a starting schedule. Match the panels to your own method.
• Mixing the two enteric-coated phases. Record the Acid Phase and the Buffer Phase separately, because switching phase clears the panels.
• Reading Pass as proof of compliance. With no limits set, the card still says Pass. Enter the limits from your specification.
• Ignoring a flagged vessel. A red vessel row does not change the verdict, but it still matters for your investigation.
• Typing potency as a fraction. Enter 99.5, not 0.995.
• Changing constants without recalculating. Standard weight, potency, dilution factor and label claim do not refresh results on screen.
• Wrong time entry. The minutes box stops at 59, so type 90 minutes as 1 h and 30 min.

What time points should I use for an immediate-release tablet dissolution test?

The calculator loads 5, 10, 15, 20, 30, 45 and 60 minutes when you pick Immediate-Release Tablet or Immediate-Release Capsule. Those are starting points for a profile. Your monograph or SOP decides which of them you actually need, and you can remove any panel you do not need or add one with the Add Time Point button.

What are the dissolution time points for sustained-release and extended-release tablets?

Sustained-Release (SR) tablets and capsules load 1, 2, 4, 6, 8 and 12 hours (60, 120, 240, 360, 480 and 720 minutes). Extended-Release (ER/XR) tablets add 16, 20 and 24 hours, giving nine points up to 1440 minutes. Controlled-Release (CR) loads 14 points between 1 and 24 hours.

How is an enteric-coated tablet tested in the calculator?

As two separate runs. After choosing Enteric-Coated Tablet or Capsule, a Test Phase menu is required: the Acid Phase loads one panel at 120 minutes (2 h in acid medium, pH 1.2, to confirm the coating holds), and the Buffer Phase loads 15, 30, 45, 60 and 90 minutes in buffer (pH 6.8) to measure release. No panels appear until you choose a phase, and switching phase clears the panels.

What time points does an ODT or chewable tablet use?

Orally Disintegrating Tablets load 5, 10, 15, 20 and 30 minutes, with a maximum of 30 minutes in the preset. Chewable Tablets load 5, 10, 15, 20, 30 and 45 minutes.

How does this calculator decide pass or fail?

It compares the mean % release of the vessels at a time point with the Min Limit and Max Limit you type for that time point. If the mean is at or above the minimum and at or below the maximum, the time point passes. There is no Q value and no Stage 1, 2 or 3 logic here. For USP <711> stage testing, use the Dissolution Calculator instead.

Why does the result say Pass when I have not entered any limits?

With no limits entered there is nothing to fail against, so the card shows Pass together with the note that no limits were set and only the calculated % release is being shown. Type a Min Limit, a Max Limit or both if you want a real acceptance check. A limit of zero counts as not set.

Can a vessel be marked as failed while the time point passes?

Yes. Each vessel row is flagged against the limits on its own, but the time point verdict is based on the mean only. A single low vessel shows a red cross in its row while the time point still passes if the mean is inside the limits.

How many vessels can I enter, and how many hours can a time point be?

Each time point starts with six vessel rows and you can add more with Add Vessel. Time is entered as hours (0 to 72) and minutes (0 to 59). At 72 hours, minutes are forced to 0.

Do I have to recalculate after changing the standard weight or potency?

Yes. Changing the time, the vessel readings, the instrument type or the absorbance range hides the affected results automatically, but editing System Configuration fields such as standard weight, potency, dilution factor or label claim does not. Click Calculate This Time Point again after any change to those fields so the result and the printed report agree.

Is the data I enter saved or sent anywhere?

The calculation, results, copy text and print preview all run in your browser, and the calculator script does not send your entries to a server.

Educational use only. This guide explains how the Dissolution by Dosage Form calculator on this site works. It is not a validated system and does not replace your monograph, your SOPs or your regulator's guidance. See the Dissolution Test theory and guidelines page for background and the disclaimer for how to use this site.