We often assume that inconsistent or low drug release during dissolution testing to product performance issues or instability of the drug at a certain pH.
But here’s the twist—sometimes the problem isn’t the drug or the formulation at all. The real culprit could be the glassware you’re using during the test!
Sounds unbelievable? That’s exactly what a study on Tacrolimus capsules by Zeng et al. uncovered. They found that Tacrolimus, a drug sensitive to multiple factors, interacts with glassware through adsorption, leading to drug loss during dissolution testing. Who would’ve thought, right?
Here are a few key takeaways from the study that apply to dissolution testing on Tacrolimus capsules:
Filtration Issues
The material and pore size of filters can affect dissolution results.
Solution:
- Use G4 glass filters or equivalent
- Passivate the filters by flushling with 2 mL of sample solution before use.
Glass Adsorption
Tacrolimus interacts with the glassware through adsorption, causing a significant drop in the drug content.
Solution:
- Add hydroxypropyl cellulose to the medium to minimize adsorption.
- Use polypropylene test tubes and HPLC vials instead of glass.
- Passivate dissolution vessels by washing with acid solution.
Sample Storage Time
Samples analyzed immediately after dissolution testing resulted in highly variable results.
Solution:
- Allow time for equilibration after dissolution testing for more reliable results.
The USP connection
These findings are in line with the USP monograph on Tacrolimus capsules, which recommends using hydroxypropyl cellulose in the dissolution medium, G4 glass filters, and specific equilibration times —6 hours for the standard and 1 hour for the sample solution for dissolution Test 1.
Read also: Cetylpyridinium Chloride (CPC) in Dissolution Bath
Resource Person: Pearl Pereira Nambiar