The two-stage biorelevant pH shift dissolution test is an essential analytical method used to simulate the physiological conditions of the gastrointestinal tract. This test is crucial for evaluating the dissolution characteristics of orally administered drug formulations. The procedure mimics the transition from the acidic environment of the stomach to the more neutral conditions of the small intestine, thus providing insights into the drug's performance in vivo.
Materials and Preparation:
- Fasted State Simulated Gastric Fluid (FaSSGF)
- Volume: 2 L
- Fasted State Simulated Intestinal Fluid (FaSSIF) Double Concentrate
- Volume: 2 L
Preparation Steps:
1. Buffer Solution: Dissolve 1.68 g NaOH pellets, 15.82 g sodium dihydrogen phosphate monohydrate (or 13.75 g sodium dihydrogen phosphate anhydrous), and 24.74 g NaCl in approximately 1.9 L of purified water. Adjust the pH to 7.5 with NaOH solution, and then adjust the volume to 2 L.
2. FaSSIF Solution: Dissolve 8.96 g of FaSSIF, FeSSIF & FaSSGF Powder in about 1.5 L of the prepared phosphate buffer. Stir until a clear solution is obtained, then adjust the volume to 2 L. This solution is now double-concentrated FaSSIF.
Procedure
Step 1: Equilibration
- FaSSGF Equilibration: Equilibrate 250 mL of FaSSGF in each dissolution vessel to 37°C ± 0.5°C. Prepare an additional vessel for volume replacement.
- FaSSIF Equilibration: Equilibrate 1.5 L of FaSSIF double concentrate (or 6 beakers with 250 mL each) to 37°C ± 0.5°C. Also prepare an additional vessel with a 1:1 mixture of FaSSGF and FaSSIF concentrate for volume replacement.
Step 2: Dissolution in FaSSGF
- Conditions: Run the dissolution test in FaSSGF at a paddle speed of 75 rpm.
- Sampling Points: 5, 10, 20, and 30 minutes.
- Filtration: Use a 0.45µm filter to filter the sample, discarding the first 2-3 mL before collecting the sample for analysis. Replace the sampled volume with pre-warmed FaSSGF.
Step 3: pH Shift and Dissolution in Mixed Media
- Transition: Immediately after the 30-minute sample, add 250 mL of pre-heated FaSSIF double concentrate to achieve a final volume of ~500 mL and a pH of ~6.5.
- Sampling Points: 35, 40, 50, 60, 90, and 120 minutes (equivalent to 5, 10, 20, 30, 60, and 90 minutes post media change).
- Filtration: Use a new 0.45µm filter for samples taken after the media change, discarding the first 2-3 mL before collecting the sample. Replace the sampled volume with a pre-warmed 1:1 mixture of FaSSGF and FaSSIF concentrate.
Analysis:
- Sample Preparation, Filtration ,Dilution
Calibration
Calibration Curves: Establish two calibration curves: one with FaSSGF as the medium for samples in FaSSGF, and another with the 1:1 mixture of FaSSGF and FaSSIF concentrate for samples after the media change. Once the calibration curves are established, a single standard may suffice for routine analysis.
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Resource Person: Prakash Amate
