How does gelatin stabilise vaccines and biologics?

Beyond Biopharma · Pharmaceutical Gelatin FAQ

Short answer: In vaccines and biologics, protein-like stabilisers based on hydrolysed (non-gelling) gelatin-type ingredients are used to shield delicate actives from the stresses of freeze-drying, freezing and long storage, helping to preserve potency until the product is used. Such excipients do not act as a thermosetting gel the way capsule gelatin does, and their use is always specific to the individual vaccine or biologic and its approved regulatory documentation.

Why biologics need help to survive

Vaccines and biologic medicines are fragile. Their active component is usually a living or protein-based entity — a virus, an antigen, an antibody, an enzyme — that can lose activity when exposed to heat, freezing, pH shifts, or the water that gets pulled away during drying. Because a dose has to stay effective from the moment it is filled until it is injected months or years later, manufacturers add stabilisers whose entire job is to keep those delicate molecules active through the harshest steps it will face.

The most stressful moment: drying it down

The single harshest step for many biologics is lyophilisation — freeze-drying. Water is frozen and then sublimated away under vacuum to leave a dry powder or cake that is far more stable at room or refrigerated temperature. That process is very stressful for a protein: ice crystals form, solutes concentrate, and surfaces open up that a molecule can stick to and unfold. Stabilisers step in to cushion those stresses — some act as glass-forming bulking agents, some replace the water's hydrogen bonds once it is gone, and some shield the active from surface contact or ice.

What sort of gelatin-like protein is actually used

It is important to be precise here. The thermosetting, high-Bloom capsule gelatin we cover elsewhere in this FAQ is not what vaccine formulators typically add. What appears in biologics and many sterile products is instead a hydrolysed (non-gelling) or collagen-derived protein fraction that has been broken into water-soluble peptides and therefore does not gel and does not set a shell. Because these hydrolysed materials are broadly considered safe protein excipients, derivatives of animal-derived collagen — depending on the specific raw material and process — have a long history in stabilising formulations.

What such an excipient is expected to do

• Protect during freeze-thaw — help keep the active folded and dissolved through freezing and thawing.
• Protect during lyophilisation — support a stable cake and keep the active from sticking to the glass or losing structure as water is removed.
• Safeguard potency in storage — maintain the biological activity of the product for its whole labelled life.

Exactly how much protection a given hydrolysate provides depends on its peptide size and composition, the concentration used, the other excipients, and — decisively — the specific active it is protecting. One stabiliser recipe that works for one antigen may be useless for another, which is why vaccine stabilisation is developed and locked product by product.

Source, purity and endotoxin are the gatekeepers

In a sterile biologic, gelatin-derived excipients face far stricter control than food or capsule grade material: tight endotoxin limits, low bioburden, defined amino-acid and molecular-weight profiles, traceable sourcing, and cleanliness through the whole manufacturing chain. The result is that a "pharmaceutical gelatin" range typically spans the gelling capsule/coating grades used as oral excipients and the hydrolysed, tighter-spec material relevant to sterile biologics — and the two should not be confused. Purity and process requirements are set by the product's regulatory file, so the right comparison is always against the specific monograph and supplier COA for that use.

Practical advice

If you are developing a vaccine, biologic or sterile product and are evaluating a collagen-derived stabiliser, treat every generalisation with care:

• Confirm which material — gelling gelatin, hydrolysed non-gelling peptides or another derivative and which animal source — your formulation genuinely calls for.
• Confirm the endotoxin, bioburden and functional requirements against the relevant pharmacopoeia and regulatory guidance for your market.
• Because statements here may not carry over to your active, verify stabilisation behaviour in your own freeze-drying studies and, for any regulated claim, ask your regulatory contact or supplier for the current, applicable answer rather than relying on a summary.