In the design and development of pharmaceutical and nutraceutical products, the selection of primary packaging directly impacts stability, bioavailability, and packaging line performance. Choosing the right raw material is not limited to defining the size; it requires a deep analysis of the physicochemical interaction between the formulation and the shell.
Below, we analyze the fundamental technical parameters to evaluate when establishing criteria for how to choose empty capsules to ensure production process efficiency.
Practical guide to pharmaceutical formulation
1. Relative humidity and API sensitivity
The hygroscopic behavior of the active pharmaceutical ingredient (API) or excipients is the first technical filter.
- Fórmulas sensibles a la humedad: Si el ingrediente activo se degrada en presencia de agua (hidrólisis), las cápsulas de gelatina tradicional (que manejan humedades del 13% al 16%) pueden transferir humedad al núcleo. En estos casos, las cápsulas vegetales (HPMC), con un rango de humedad del 4% al 6%, ofrecen una barrera de protección superior.
- Moisture-sensitive formulations: If the active ingredient degrades in the presence of water (hydrolysis), traditional gelatin capsules (which maintain moisture levels of 13% to 16%) can transfer moisture to the core. In these cases, vegetable capsules (HPMC), with a moisture range of 4% to 6%, provide a superior protective barrier.
2. Rheological behavior and machine performance
The speed and efficiency of encapsulating machines depend heavily on the mechanical properties of the raw material.
- Resistance to brittle fracture: Capsules must withstand the forces of separation, dosing, and closing of industrial equipment without cracking, especially in environments with plant temperature and humidity variations.
- Dimensional stability: Low variability in capsule dimensions prevents unscheduled line downtime caused by jams in the capsule filler’s rectification pins.
3. Chemical interactions and cross-linking reactions
Certain excipients, aldehydes, or environmental conditions (such as combined heat and humidity exposure) can induce cross-linking reactions in animal gelatin, altering in vitro disintegration times.
- If the formulation carries risks of interaction with animal proteins, alternative polymer shells such as Pullulan or HPMC ensure complete chemical inertness, maintaining a constant dissolution profile throughout the product’s shelf life.
4. Oxygen barrier requirements and target markets
For active ingredients prone to oxidation (such as certain natural extracts, vitamins, or essential oils), the oxygen permeability of the shell is critical.
- While gelatin and HPMC offer standard protection, Pullulan capsules stand out by providing a significantly superior oxygen barrier, protecting highly volatile formulations without requiring complex secondary packaging conditions.
| Evaluation Parameter | Gelatin Capsule | Vegetable Capsule (HPMC) | Pullulan Capsule |
|---|---|---|---|
| Internal Moisture | Medium-High (13-16%)Medium (10-14%) | Low (4-6%) | |
| Cross-Linking Risk | Present | None | None |
| Oxygen Barrier | Standard | Standard | High / Superior |
| Industrial Mechanical Performance | Excellent | Very Good | Very Good |
Conclusion
Optimizar los criterios de selección de cápsulas vacías previene fallas de estabilidad, reduce mermas en producción y asegura el cumplimiento de los estándares de calidad exigidos por la industria.
At Globalquimia, we offer a specialized portfolio and technical advisory to help you determine the exact raw material required for your pharmaceutical or nutraceutical project.
Do you have questions regarding the formulation of your next batch? Contact our team for comprehensive technical guidance.
Reference sources notice
The information shared in this article is strictly for informational purposes. Mentioned names, regulations, and brands (such as USP or ICH) belong to their respective owners and are cited solely as supporting bibliographical references, implying no commercial association or direct liability of Globalquimia Ltda over these external entities.
United States Pharmacopeia (USP)
