Top 10 Interview questions about Dissolution apparatus.
1. What is a dissolution apparatus? Why is it used?
A dissolution apparatus is a lab device used to measure the rate at which a drug is released from a dosage form (like a tablet or capsule) into a solution. It’s a key tool in drug development and quality control to ensure consistent drug release and bioavailability.
2. What are the different types of dissolution apparatus as per USP?
USP <711> specifies the following types:
- Apparatus 1: Basket
- Apparatus 2: Paddle
- Apparatus 3: Reciprocating cylinder
- Apparatus 4: Flow-through cell
- Apparatus 5: Paddle over disk
- Apparatus 6: Rotating cylinder
- Apparatus 7: Reciprocating holder
3. What are the critical parameters in a dissolution test?
- Apparatus type
- Rotation speed (RPM)
- Dissolution medium (type, volume, pH)
- Temperature (usually 37 ± 0.5°C)
- Sampling time points
- Sink conditions
4. What is sink condition in dissolution testing?
Sink condition refers to the ability of the dissolution medium to dissolve at least three times the amount of drug present in the dosage form. It ensures proper release and avoids saturation.
5. What is the difference between Apparatus 1 (Basket) and Apparatus 2 (Paddle)?
Basket (Apparatus 1): Dosage is placed in a mesh basket that rotates. Used for floating or capsule-type dosage forms.
Paddle (Apparatus 2): Dosage rests at the bottom of the vessel, and a paddle stirs the medium. Used for tablets.
6. How do you calibrate a dissolution apparatus?
- Mechanical calibration: Verifying RPM, temperature, shaft centering, vessel dimensions, etc.
- Performance verification test (PVT): Using USP Prednisone tablets to check system suitability.
7. What are common problems during dissolution testing?
- Air bubbles on tablets
- Tablet sticking to the vessel wall
- Poor de-aeration of medium
- Improper RPM or temperature
- Sampling errors or contamination
8. How is sample withdrawal done and why is filtration important?
Samples are withdrawn at defined time points and usually filtered immediately to remove undissolved particles, preventing further dissolution in the collected sample.
9. What are dissolution profiles and how are they compared?
Dissolution profiles show the % drug release over time. Profiles are compared using similarity (f2) and difference (f1) factors, especially during generic development or stability studies.
10. What is the role of dissolution testing in IVIVC (In Vitro-In Vivo Correlation)?
Dissolution helps predict how a drug behaves in the body (bioavailability). A strong IVIVC allows dissolution data to serve as a surrogate for in vivo studies, saving time and cost.
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