Controlled release

In brief

Controlled release means the shell lets go of its active gradually, under defined conditions, rather than all at once. It is a property of the formulation, measured in the laboratory, and it describes timing. It is one of the NanoVeil properties summarized on the Technology hub.

Immediate and controlled release

In a conventional serum the active is dissolved in the base. The moment the serum is spread, all of it is available at once. That is immediate release.

In an encapsulated serum the active starts inside a shell. It becomes available as the shell releases it, a portion at a time. That is controlled release, sometimes called gradual or sustained release. NanoVeil builds a multi-layer biopolymer shell around an active, up to 20 programmable layers, so the active is held stable until defined conditions release it. How the shell is built is on How encapsulation works.

What triggers release

A shell is designed to stay closed in one environment and open in another. In the bottle, the conditions keep the shell intact and the active protected, as described on Stability and protection. On the skin surface, the conditions change, and the shell begins to release its contents.

In the layer-by-layer literature, release is governed by the number and order of layers and by how the layers respond to their surroundings. More layers generally slow release; the choice of polymer sets what the shell responds to. Other carrier families release by different routes, compared on Carrier systems compared.

How release is measured

Release is measured in vitro. The encapsulated active is placed in a test medium that reproduces the target conditions, samples are drawn at set intervals, and the amount of free active is measured each time. The result is a release profile: the percentage of active released, plotted against time.

This is formulation data, graded Level B on the Vegalab scale. How that level is defined, and what it supports, is on Evidence levels. How the finished products are tested is on How we test.

The scope of the term

On Vegalab pages, controlled release carries only the meaning above: when the active leaves the shell, on the skin surface.

Timing. The amount of active in the bottle is fixed by the formula and stated in the ingredient declaration. Release sets when it becomes available.

One formula. A release profile is a Level B formulation measurement for one formula. Statements about how skin looks or feels after use come from testing of the finished product on people, graded Level C.

Why gradual release matters in formulation

Some actives are better tolerated when they become available gradually rather than in a single peak. Exfoliating acids are the familiar case: salicylic acid and AHAs can feel sharp when the whole dose is free at once. Gradual availability is a formulation choice that addresses how a product feels in use. The NanoSerum formulas, including the Clarifying NanoSerum vial set, the Brightening NanoSerum vial set and the Hyaluronic Skin Repair vial set, are built on the NanoVeil platform. Each product page carries the full ingredient declaration.

For the size of the capsules that carry out this release, see Particle size. Terms are defined in the glossary.

References

The studies below describe the technology in general.

1. Siepmann J, Siepmann F. Mathematical modeling of drug delivery. International Journal of Pharmaceutics. 2008;364(2):328-343.
2. Decher G. Fuzzy nanoassemblies: toward layered polymeric multicomposites. Science. 1997;277(5330):1232-1237.