Dissolution Calculator (Immediate Release) — USP <711> S1/S2/S3 Stages

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Industry Use

Dissolution Testing in Quality Control

Dissolution testing verifies that a solid dosage form releases its active pharmaceutical ingredient (API) at the required rate under physiological conditions simulated in vitro. USP <711> governs immediate release (IR) product testing and is fundamental to batch release, product development, and regulatory submission.

Key Applications:

Batch Release: Dissolution results confirm that each manufactured batch meets product specification for API release at defined time points.
Product Development: Dissolution profiles guide formulation optimization and demonstrate bioavailability correlation.
Bioequivalence (BE): Dissolution profiles are part of the BE rationale; in vivo BE can be waived for BCS Class I and Class III drugs with appropriate dissolution performance (ICH M9, 2019; FDA BCS guidance).
Stability Testing: Long-term and accelerated stability protocols include dissolution at time zero, 3, 6, 9, 12, 18, and 24 months to detect API degradation or formulation changes.
Post-Approval Changes: SUPAC guidance recommends dissolution testing when formulation, manufacturing process, or equipment changes occur (as guidance, its provisions are phrased as “should,” not requirements).

The three-stage sampling plan (S1, S2, S3) efficiently evaluates batch conformance while minimizing unnecessary testing of acceptable batches.

USP <711> FDA SUPAC ICH M9

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Calculation Explanation

Three-Stage Acceptance Criteria

Dissolution testing employs a sequential stage approach where dissolution is evaluated at a single time point (usually the labeled release time) for each stage. The specification Q represents the percentage of API that should be dissolved at that time point.

Stage 1 (S1) — Initial Sample (n=6 vessels):

Stage 1 Acceptance Criterion

Each individual unit ≥ Q + 5%

If all 6 results are ≥ Q+5%, the batch PASSES. If any result is < Q+5%, proceed to Stage 2.

Stage 2 (S2) — Pooled Analysis (n=12 total vessels):

Test 6 additional units (combine with Stage 1 for n=12 total).

Stage 2 Acceptance Criteria

• Average of 12 units ≥ Q
• No individual unit < Q − 15%

If both conditions are met, the batch PASSES. If not, proceed to Stage 3.

Stage 3 (S3) — Extended Analysis (n=24 total vessels):

Test 12 additional units (combine with Stages 1 and 2 for n=24 total).

Stage 3 Acceptance Criteria

• Average of 24 units ≥ Q
• Not more than 2 units < Q − 15%
• No individual unit < Q − 25%

If all three conditions are met, the batch PASSES. If any condition fails, the batch FAILS and requires investigation.

Illustrative Q values for immediate release (always set per the product monograph or approved specification):

Time Point	Typical Q Value	Purpose
15 min	—	Not usually a Q specification; ≥85% dissolved in 15 minutes is the rapid-dissolution benchmark used in biowaiver comparisons
30 min	Q = 75–80%	Common primary time point for IR products
45 min	Q = 75–80%	Alternative primary time point for slower-dissolving IR products

USP <711> Q Specification S1/S2/S3 Plan

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Variable Definitions

Dissolution Testing Parameters

Symbol	Parameter Name	Units	Description
Q	Dissolution Specification	% Released	Target percentage of API dissolved at the specified time point. Set per product monograph (commonly Q = 75–80% at the primary time point).
n	Number of Vessels/Units	vessels	Stage 1: n=6; Stage 2: n=12 (cumulative); Stage 3: n=24 (cumulative).
Individual Dissolution	Individual Unit Result	% Released	Dissolution value for each vessel, expressed as percentage of label claim released at the time point. Results above 110% are accepted with a warning (USP <711> imposes no cap, and modest excursions above label can occur); values above 150% are rejected as implausible.
Average Dissolution	Mean Dissolution	% Released	Arithmetic mean of all n individual results at the time point.
Stage	Testing Phase	S1/S2/S3	Stage 1, 2, or 3 of the sequential sampling plan. Each stage has distinct acceptance criteria.

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Step-by-Step Tutorial

Worked Example with Immediate Release Tablet

Scenario: A pharmaceutical manufacturer is conducting batch release dissolution testing for an immediate release tablet containing 200 mg ibuprofen. Dissolution is tested at 30 minutes in pH 7.2 phosphate buffer at 37°C using USP Apparatus II (paddle). The product specification is Q = 80% at 30 minutes.

Stage 1: Dissolution Results at 30 minutes (n=6 vessels)

Individual Dissolution Values (% Released):
87%, 89%, 85%, 91%, 88%, 86%

Establish Stage 1 Acceptance Criterion:
Q + 5% = 80% + 5% = 85%
Criterion: Each unit ≥ 85%
Compare Each Result Against Criterion:
Vessel 1: 87% ≥ 85% ✓
Vessel 2: 89% ≥ 85% ✓
Vessel 3: 85% ≥ 85% ✓
Vessel 4: 91% ≥ 85% ✓
Vessel 5: 88% ≥ 85% ✓
Vessel 6: 86% ≥ 85% ✓
Evaluate Stage 1 Acceptance:
All 6 results are ≥ Q + 5% (≥85%).

✓ BATCH PASSES STAGE 1
All 6 vessels exceeded 85% dissolution at 30 minutes.
No further testing required.

Alternative Scenario (if Stage 1 failed): If one vessel in Stage 1 had returned 82% (below 85%), the batch would not pass Stage 1 and would proceed to Stage 2 with 6 additional vessels (n=12 total). The Stage 2 criterion requires the average of all 12 units ≥ 80% (Q) and no unit < 65% (Q − 15%).

Interpretation: The batch demonstrates excellent and consistent API release with all individual results exceeding the lower bound specification, indicating robust formulation performance and manufacturing consistency.

PharmaCalc

Dissolution (Immediate Release) — USP <711>

Industry Use

Calculation Explanation

Variable Definitions

Step-by-Step Tutorial