The Film-Forming Polymers Behind an Oral Dissolving Strip

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By Jack Zheng, MS Pharmacy — Founder of MIHIYO Labs

Summary

Oral dissolving strips are thin polymer films, and the polymer choice determines whether the strip works. Hydroxypropyl methylcellulose (HPMC) and pullulan, a fermentation product of Aureobasidium pullulans, are two widely used film-forming polymers with different trade-offs: pullulan disintegrates fast but is brittle without a plasticizer like glycerol, while HPMC is more robust but hydrates more slowly. Separately, blending HPMC with a different cellulose derivative, hydroxypropyl cellulose (HPC), shows that raising HPC content past 40 percent shortens disintegration time at the cost of film strength. An oral dissolving strip (ODS) is only as good as these trade-offs. MIHIYO Labs matches polymer systems to each active dose and dissolution target.

What Polymer Makes an Oral Dissolving Strip Dissolve?

Most often, one of two widely used film-forming polymers: hydroxypropyl methylcellulose (HPMC), a cellulose derivative, or pullulan, a polysaccharide produced by fermenting the yeast-like fungus Aureobasidium pullulans¹. Other film formers — hydroxypropyl cellulose (HPC), polyvinyl alcohol, sodium carboxymethylcellulose, pectin — show up too, often blended in rather than used alone⁵. Both HPMC and pullulan form a continuous, flexible film when cast from a water-based solution and dried, and both hydrate fast enough in saliva to disintegrate without water — unlike conventional swallowed tablets, which are not designed to disintegrate rapidly in saliva. Everything else in an oral dissolving strip (ODS) — the plasticizer, the sweetener, the active ingredient itself — sits inside whichever polymer matrix the formulator picks. In my formulation work, the polymer is the first decision, not an afterthought, because it sets the ceiling on how fast the strip dissolves and how much of a dose it can physically carry.

How Film-Forming Polymers Turn a Cast Solution Into a Strip

A film-forming polymer is a long-chain molecule that, dissolved in water at the right concentration, entangles with its neighboring chains as the water evaporates during drying. Those entangled chains are what hold a strip together as a solid sheet instead of a crumbling powder. The manufacturing method is solvent casting: polymer, plasticizer, and active are dissolved or dispersed together, cast onto a flat surface, and dried into a film that is then cut into unit doses⁵.

HPMC is made by treating cellulose — the structural polymer in plant cell walls — with propylene oxide and methyl chloride, replacing some of the hydroxyl groups with methoxy and hydroxypropyl substituents. The degree of that substitution, together with the polymer's molecular weight, sets its viscosity grade, which pharmacopeial suppliers report as a range from about 3 to 100,000 mPa·s in a 2 percent aqueous solution — a higher average molecular weight raises viscosity. Low-molecular-weight, low-viscosity HPMC is the grade formulators reach for as a fast-dissolving film former; higher-viscosity grades are reserved for controlled-release tablet coatings, where slow hydration is the goal instead³.

Pullulan works differently. It is a linear polysaccharide built from repeating maltotriose units, water-soluble, tasteless, and odorless in its raw form, which is part of why it became a food and pharmaceutical film staple long before it appeared in supplement strips¹. Pullulan-based oral films often disintegrate within one minute, but pullulan films can be brittle without a plasticizer — they crack and tear without help. A 2017 factorial study testing glycerol, vitamin E TPGS, and triacetin as plasticizers found glycerol produced the greatest elongation at break, at 20 percent w/w, and that the majority of the resulting films still disintegrated within one minute regardless of which plasticizer was used². The plasticizer is not cosmetic. It is what keeps a pullulan strip from snapping between the foil pouch and your fingers.

How Do HPMC and Pullulan Compare as Film-Forming Agents?

HPMC and pullulan can be blended together, but the 2025 study discussed below is a separate cellulose-derivative blend system — HPMC with HPC — not a pullulan blend. Neither HPMC nor pullulan wins on every axis on its own: pullulan disintegrates faster but is weaker unplasticized, while HPMC is more mechanically robust but slower to hydrate. That 2025 study targets HPMC's own disintegration speed directly by casting films from ratios of HPMC and hydroxypropyl cellulose (HPC) — a related but distinct cellulose derivative — ranging from 100:0 to 20:80, then measured tensile strength, elastic modulus, elongation at break, and disintegration time. Blends containing more than 40 percent HPC shortened disintegration time compared with lower-HPC blends, although tensile strength and elastic modulus declined progressively as HPC content rose, with the most HPC-heavy ratios (60:40 and 80:20) showing the weakest mechanical performance. When the researchers loaded the films with donepezil hydrochloride as a model active, the drug itself partly offset that mechanical decline in the blended films compared with single-polymer films⁴. The takeaway for a formulator is blunt: faster disintegration and higher mechanical strength pull in opposite directions in this blend system, and the blend ratio is the lever, not a fixed recipe.

Fast-dissolving hydrophilic films — pullulan and HPMC alike — can be sensitive to ambient moisture, since the same water-solubility that lets them dissolve quickly in the mouth also lets them pick up humidity in storage. That sensitivity, more than a difference between the two polymers specifically, is a main reason ODS products typically ship in sealed, moisture-barrier foil rather than ordinary plastic packaging.

What This Means for MIHIYO's Strip Formulation

I hold every MIHIYO formulation to two metrics: bioavailability and absorption speed, meaning how much of the dose reaches the blood and how fast it gets there. The polymer choice is where that design goal either survives contact with reality or doesn't. Very rapid disintegration may reduce mucosal residence time, depending on the active ingredient's permeability and dose — a strip that dissolves in a few seconds leans closer to something swallowed than something absorbed sublingually, which cuts against the reason to use a film in the first place.

That is also why film-forming polymer choice interacts directly with dose. Orodispersible films have a practical, formulation-dependent drug-loading ceiling: research on high-load formulations shows that pushing an active past roughly 30 percent of dry film mass tends to degrade disintegration time and mechanical integrity, and even engineered high-load approaches generally top out well under what a capsule or tablet can carry — the highest commercial examples documented in the literature reach roughly 50 percent of film weight as active, and even that comes at a real cost to how fast the film breaks down⁶. This is precisely why MIHIYO strips carry low-dose, high-potency actives — melatonin in fractions of a milligram, caffeine and 5-HTP at moderate single doses — rather than bulkier ingredients like magnesium or fish oil that need a capsule's payload capacity. The film format is not a universal replacement for every dosage form; it is the right tool when the active is potent enough to fit inside a thin polymer matrix without breaking the disintegration target. The Energy-Focus, Mood-Boost, and Sleep-Support strips are all formulated within that practical ceiling, not around it.

Taste is the other constraint the polymer choice inherits. Pullulan starts out tasteless, but most active ingredients do not, and covering a bitter compound inside a fast-dissolving film usually means sweeteners like rebiana from stevia, at roughly 200 to 300 times the sweetness of sucrose, or sugar alcohols such as sorbitol and mannitol, typically added at 3 to 6 percent by weight for the intense sweeteners and used more broadly for the sugar alcohols, which also improve the film's physical integrity⁷. A film formulator is solving a taste problem and a mechanical problem in the same few percentage points of formula.

Where Film-Forming Polymers Fall Short

None of this makes the film format universal. The drug-loading ceiling is real, even if it is formulation-dependent rather than a fixed number: an oral dissolving strip is a poor vehicle for any active that needs a gram-scale dose, and no amount of polymer engineering changes that math without making the film too thick to disintegrate on target⁶. Plasticizer trade-offs are also real — because fast-dissolving hydrophilic films can be moisture-sensitive, many products require moisture-barrier packaging, and a plasticizer that improves flexibility does not remove that sensitivity. And a fast-dissolving film is still, by definition, fast — it does not hold prolonged mucosal contact the way a slower-dissolving lozenge or a buccal patch can, so it is the wrong choice when sustained, hours-long release is the actual goal rather than a quick, complete dose.

It is also worth stating plainly: the studies cited here were run on HPMC, pullulan, and HPMC/HPC blend films in laboratory formulations, using model actives like donepezil or generic film-forming trials — not on MIHIYO's own strips. What the pharmacology supports is the polymer mechanics; it is not a clinical claim about caffeine, melatonin, or 5-HTP absorption from a specific MIHIYO product.

The bottom line

An oral dissolving strip is a polymer engineering problem before it is a nutrition problem. HPMC, pullulan, and related cellulose-polymer blend systems such as HPMC/HPC set the disintegration speed, the mechanical strength, and the dose ceiling of a film-forming polymer strip, and every one of those properties trades off against the others. It is one more concrete reason why, as covered in the broader dosage-form framework, the format has to match the molecule and the use case rather than one form working best for everything. MIHIYO Labs picks the polymer ratio to match a specific active's dose and dissolution target, not the other way around, because a strip that does not disintegrate on time or hold together in the pouch is not a working oral dissolving strip (ODS) at all — it is just a film.

References

1. Singh RS, Saini GK, Kennedy JF. Pullulan: Microbial sources, production and applications. Carbohydrate Polymers. 2008;73(4):515-531. PMID: 26048217 / DOI: 10.1016/j.carbpol.2008.01.003. https://pubmed.ncbi.nlm.nih.gov/26048217/
2. Vuddanda PR, Montenegro-Nicolini M, Morales JO, Velaga S. Effect of plasticizers on the physico-mechanical properties of pullulan based pharmaceutical oral films. European Journal of Pharmaceutical Sciences. 2017;96:290-298. PMID: 27629498 / DOI: 10.1016/j.ejps.2016.09.011. https://pubmed.ncbi.nlm.nih.gov/27629498/
3. Vlad RA, Pintea A, Pintea C, Rédai EM, Antonoaea P, Bîrsan M, Ciurba A. Hydroxypropyl Methylcellulose—A Key Excipient in Pharmaceutical Drug Delivery Systems. Pharmaceutics. 2025;17(6):784. PMID: 40574096 / DOI: 10.3390/pharmaceutics17060784. https://pmc.ncbi.nlm.nih.gov/articles/PMC12196896/
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5. Irfan M, Rabel S, Bukhtar Q, Qadir MI, Jabeen F, Khan A. Orally disintegrating films: A modern expansion in drug delivery system. Saudi Pharmaceutical Journal. 2016;24(5):537-546. PMID: 27752225 / DOI: 10.1016/j.jsps.2015.02.024. https://pubmed.ncbi.nlm.nih.gov/27752225/
6. Ferlak J, Guzenda W, Osmałek T. Orodispersible Films—Current State of the Art, Limitations, Advances and Future Perspectives. Pharmaceutics. 2023;15(2):361. PMID: 36839683 / DOI: 10.3390/pharmaceutics15020361. https://pmc.ncbi.nlm.nih.gov/articles/PMC9965071/
7. Jacob S, Boddu SHS, Bhandare R, Ahmad SS, Nair AB. Orodispersible Films: Current Innovations and Emerging Trends. Pharmaceutics. 2023;15(12):2753. PMID: 38140094 / DOI: 10.3390/pharmaceutics15122753. https://pmc.ncbi.nlm.nih.gov/articles/PMC10747242/

By Jack Zheng, MS Pharmacy — Founder of MIHIYO Labs. Focused on the R&D of high-bioavailability, fast-absorption oral dissolving strips.