Coating Analysis on Pharmaceutical Tablet Forms

Significance of the Topic

The analysis of film coatings on pharmaceutical tablets is critical for ensuring product performance, stability and patient compliance. Accurate characterization of polymeric coatings, plasticizers and solvents helps in quality control, defect diagnosis and formulation optimization.

Study Objectives and Overview

This application note demonstrates the use of thermal pyrolysis coupled with gas chromatography-mass spectrometry (GC-MS) to identify and characterize coating components on solid oral dosage forms. The approach aims to provide rapid, solvent-free deformulation and detailed profiling of film coatings.

Methodology and Instrumentation

• Sample Preparation: Lightly scrape approximately 25 µg of coating material from tablet surface.
• Pyrolysis Conditions: Interface temperature set to 300 °C, pyrolysis at 750 °C for 15 s using a CDS Analytical Pyroprobe Model 2500 autosampler.
• GC-MS Setup: Hewlett-Packard 6890 gas chromatograph with 5972A mass selective detector. Carrier gas helium at 5.9 psi, split ratio 50:1. Column HP-5 (30 m × 250 µm × 0.25 µm). Oven program starts at 40 °C (2 min), ramps at 6 °C/min to 295 °C, holds for 10 min.

Main Results and Discussion

• Methyl Methacrylate: Identified as the primary polymer monomer via a distinct peak in the chromatogram after pyrolysis of tablet coating scrapings.
• Plasticizer (Ethyl Citrate): Detected and quantified by its characteristic retention time and mass spectrum, confirming its role in coating flexibility and adhesion.
• Solvent Residue (Isopropyl Alcohol): Observed early in the chromatogram, demonstrating residual solvent distribution and potential impact on coating uniformity.

Benefits and Practical Applications

• Rapid Screening: Pyrolysis GC-MS bypasses lengthy solvent extraction, enabling fast deformulation of solid dosage coatings.
• Comprehensive Profiling: Simultaneous detection of polymers, plasticizers and residual solvents supports formulation development and troubleshooting.
• Quality Control: Quantitative analysis aids in batch consistency checks and regulatory compliance.

Future Trends and Applications

Advancements in pyrolysis interfaces and high-resolution mass spectrometry could enhance sensitivity and compound identification. Integration with chemometric tools may allow for automated fingerprinting of coating formulations in real time. Expanding applications include complex multilayer coatings and real-time manufacturing process monitoring.

Conclusion

Pyrolysis GC-MS offers a powerful, solvent-free approach for the detailed analysis of pharmaceutical tablet coatings. This method streamlines deformulation, yields comprehensive component profiles and supports both research and routine quality control in pharmaceutical development.

References

• Porter SC. Coating of Pharmaceutical Dosage Forms. In Remington: The Science and Practice of Pharmacy. 19th ed. Gennaro AR, editor. Mack Publishing; 1995.
• Wampler T. Analytical Pyrolysis: An Overview. In Applied Pyrolysis Handbook. Wampler TP, editor. Marcel Dekker; 1995.