- Dissolution Test Topic covers below points:
- Dissolution Test Principle
- Dissolution Test Apparatus
- Dissolution Test Procedure
- Dissolution Test Sampling Point
- Dissolution Test Acceptance Criteria as per USP
- Dissolution Test Acceptance Criteria as per BP
Dissolution Test Principle : A dissolution test is a pharmaceutical quality control procedure used to determine how quickly and completely a solid dosage form, such as a tablet or capsule, dissolves in a specified liquid medium. The test mimics the conditions inside the human body, where the drug is expected to dissolve in the digestive system. By measuring the rate and extent of dissolution, it ensures that the drug will be released and absorbed properly, which is crucial for its effectiveness and safety. The results of dissolution tests are important for regulatory compliance, batch-to-batch consistency, and the development of pharmaceutical formulations.
Dissolution tests are an essential part of pharmaceutical quality control, and there are several types of dissolution tests, each designed for specific drug formulations and release mechanisms. Here are some common types:
- Immediate Release (IR) Dissolution Test:
This type of test is used for conventional solid dosage forms, such as tablets and capsules, where the drug is intended to be rapidly released and absorbed. - Extended Release (ER) Dissolution Test:
For medications designed to release the drug gradually over an extended period, like extended-release tablets or capsules, specialized dissolution tests are conducted. These tests often involve different dissolution apparatuses and longer testing durations. - Modified-Release Dissolution Test:
Drugs with complex release profiles, like pulsatile or biphasic release, require modified-release dissolution tests. These tests may involve changing the dissolution medium or using specific apparatuses to simulate the intended drug release pattern. - Topical and Transdermal Dissolution Test:
These tests are performed on topical products, such as creams, ointments, and transdermal patches, to assess the release of drugs through the skin. - Inhalation Dissolution Test:
For inhaled pharmaceuticals, like dry powder inhalers or metered-dose inhalers, dissolution tests are customized to simulate the dissolution of drug particles in the respiratory system. - Suppository Dissolution Test:
Suppositories, which are inserted into the rectum, undergo specific dissolution tests to evaluate the release of the drug from the suppository base.
Various Apparatus Used For Dissolution Study According To USP
- Apparatus 1 (Rotating basket)
- Apparatus 2 (paddle assembly)
- Apparatus 3 (Reciprocating cylinder)
- Apparatus 4 ( Flow through cell)
- Apparatus 5 (Paddle overdisc)
- Apparatus 6 (cylinder)
- Apparatus 7 (Reciprocating holder)
Dissolution Test Procedure : Place the stated volume of the dissolution medium (± 1 per cent) in the vessel of the specified apparatus. Assemble the apparatus, equilibrate the dissolution medium to 37 ± 0.5 °C.
Place 1 dosage unit in the apparatus, taking care to exclude air bubbles from the surface of the dosage unit. Operate the apparatus at the specified rate. Within the time interval specified, or at each of the times stated, withdraw a specimen from a zone midway between the surface of the dissolution medium and the top of the rotating basket or blade, not less than 1 cm from the vessel wall.
Where multiple sampling times are specified, replace the aliquots withdrawn for analysis with equal volumes of fresh dissolution medium at 37 °C or, where it can be shown that replacement of the medium is not necessary, correct for the volume change in the calculation. Keep the vessel covered for the duration of the test and verify the temperature of the medium at suitable times.
Dissolution medium: A suitable dissolution medium is used. The volume specified refers to measurements made between 20 °C and 25°C. If the dissolution medium is a buffered solution, adjust the solution so that its pH is within 0.05 units of the specified pH. Dissolved gases can cause bubbles to form, which may change the results of the test. In such cases, dissolved gases must be removed prior to testing.
Time: Where a single time specification is given, the test may be concluded in a shorter period if the requirement for minimum amount dissolved is met. Samples are to be withdrawn only at the stated times, within a tolerance of ± 2 per cent.
Dissolution Test Sampling Point: The samples are withdrawn from a zone midway between the surface of the dissolution medium and the top of the rotating basket or blade, not less than 1 cm from the vessel wall.
For Operation of Dissolution Test Apparatus SOP click link: Operation of Dissolution Test Apparatus SOP
Dissolution Test Acceptance Criteria as per United States Pharmacopeia – USP
Where, Q – Amount of dissolved active ingredient specified in the individual monograph expressed as a percentage of content
1. Acceptance Criteria For Immediate-Release Dosage Forms:
| STAGE | NUMBER TESTED | ACCEPTANCE CRITERIA |
| S1 | 6 | Each unit is NLT Q + 5% |
| S2 | 6 | Average of 12 units (S1 + S2) is equal to or greater than Q, and no unit is less than Q – 15%. |
| S3 | 12 | Average of 24 units (S1 + S2 +S3) is equal to or greater than Q, not more than 2 units are less than Q – 15%, and no unit is less than Q – 25%. |
2. Acceptance Criteria For Immediate-Release Dosage Forms Pooled Sample:
| STAGE | NUMBER TESTED | ACCEPTANCE CRITERIA |
| S1 | 6 | Average amount dissolved is not less than Q + 10%. |
| S2 | 6 | Average amount dissolved (S1 + S2) is equal to or greater than Q + 5%. |
| S3 | 12 | Average amount dissolved (S1 + S2 + S3) is equal to or greater than Q. |
3. Acceptance Criteria For Extended-Release Dosage Forms:
| LEVEL | NUMBER TESTED | ACCEPTANCE CRITERIA |
| L1 | 6 | No individual value lies outside each of the stated ranges and no individual value is less than the stated amount at the final test time. |
| L2 | 6 | The average value of the 12 units (L1 + L2) lies within each of the stated ranges and is not less than the stated amount at the final test time; none is more than 10% of labeled content outside each of the stated ranges; and none is more than 10% of labeled content below the stated amount at the final test time. |
| L3 | 12 | The average value of the 24 units (L1 + L2 + L3) lies within each of the stated ranges, and is not less than the stated amount at the final test time; not more than 2 of the 24 units are more than 10% of labeled content outside each of the stated ranges; not more than 2 of the 24 units are more than 10% of labeled content below the stated amount at the final test time; and none of the units is more than 20% of labeled content outside each of the stated ranges or more than 20% of labeled content below the stated amount at the final test time. |
4. Acceptance Criteria For Delayed-Release Dosage Forms:
A. Acid stage:
| LEVEL | NUMBER TESTED | CRITERIA |
| A1 | 6 | No individual value exceeds 10% dissolved. |
| A2 | 6 | Average of the 12 units (A1 +A2) is not more than 10% dissolved, and no individual unit is greater than 25% dissolved. |
| A3 | 12 | Average of the 24 units (A1 + A2 +A3) is not more than 10% dissolved, and no individual unit is greater than 25% dissolved. |
B. Buffer stage:
| LEVEL | NUMBER TESTED | CRITERIA |
| B1 | 6 | Each unit is not less than Q + 5%. |
| B2 | 6 | Average of 12 units (B1 + B2) is equal to or greater than Q, and no unit is less than Q – 15%. |
| B3 | 12 | Average of 24 units (B1 + B2 + B3) is equal to or greater than Q, not more than 2 units are less than Q – 15%, and no unit is less than Q – 25%. |
Dissolution Test Acceptance Criteria as per British Pharmacopoeia – BP
Where, Q – Amount of dissolved active ingredient specified in the individual monograph expressed as a percentage of content
1. Conventional-release solid dosage forms:
2. Prolonged-release dosage forms:
3. Delayed-release dosage forms:
A. Acid stage:
B. Buffer stage:
- Reference :
- United States Pharmacopeia
- British Pharmacopoeia
For Calibration of Dissolution Test Apparatus SOP click link: Calibration of Dissolution Test Apparatus SOP