Key facts
- Liposomes can change physically (aggregation, fusion, leakage) and chemically (oxidation, hydrolysis).
- Size, PDI, zeta potential, encapsulation and active content are the numbers to track.
- Real-time data at the storage condition you will actually use is the strongest evidence.
- Storage, packaging and handling matter as much as the formulation.
What changes over time
A liposomal preparation is a dispersion of tiny vesicles, and dispersions are never perfectly static. Two kinds of change matter.
Physical changes
- Aggregation and fusion — vesicles clump or merge into larger ones, so average size and PDI rise.
- Leakage — the encapsulated active escapes into the surrounding liquid, so encapsulation efficiency falls.
- Sedimentation or creaming — large aggregates separate from the liquid.
Chemical changes
- Lipid oxidation — unsaturated phospholipids react with oxygen, which can change the bilayer and produce off-notes.
- Hydrolysis — phospholipids can break down in water, especially away from a mildly acidic-to-neutral pH, forming lysophospholipids that disturb the bilayer.
- Active degradation — the encapsulated active itself may be sensitive to light, oxygen or heat.
What to track
| Measure | A drift suggests |
|---|---|
| Average size and PDI | Aggregation or fusion |
| Zeta potential | Weaker repulsion between vesicles, so aggregation risk |
| Encapsulation efficiency | Leakage of the active |
| Active content | Degradation or loss of the active |
| pH | Hydrolysis or microbial activity |
| Appearance and odour | Oxidation, separation or contamination |
Designing for stability
- Lipid choice. More saturated phospholipids oxidise less but give a more rigid bilayer; the balance depends on the active and the format.
- Antioxidants. Lipid-soluble antioxidants such as tocopherol can be built into the bilayer to slow oxidation.
- pH and ionic strength. Keep the medium in the range that limits hydrolysis and keeps vesicles apart.
- Protectants for dry formats. Sugars such as trehalose help vesicles survive drying and reconstitution.
- Packaging. Light-protective, low-oxygen packaging helps oxidation-prone products.
Storage and handling
- Follow the supplier's stated storage condition and keep it consistent.
- Avoid freezing a liquid liposomal preparation unless the supplier has validated it; ice crystals can rupture vesicles.
- Protect from light and heat, and keep containers closed to limit oxygen exposure.
- Handle gently. Avoid vigorous shaking or repeated temperature cycling.
Reading a stability study
A credible stability claim names the format, the storage condition and the time points, and reports the measures above — not just the final active content.
- Real-time data at the condition you will use is the strongest evidence for shelf life.
- Accelerated data (elevated temperature) gives early warning but is not a substitute for real-time data.
- Same format as yours. Data for a liquid does not transfer to a powder, or to a different pH or excipient set.
- Batch information. Data from more than one batch shows repeatability.
What Lipologics provides
Lipologics supplies nano-liposomal ingredients on the HNOVA™ platform, developed and manufactured in Jigani, Bengaluru, with per-ingredient specification sheets and Certificates of Analysis. Stability information for a specific ingredient and format is shared on request for your programme. Browse the ingredient range, read about particle size, or contact the team.
