A 22 × 32 mm strip holds roughly 100 to 300 mg of dry film, and published oral films load actives at about 5 to 30 % of dry weight. That puts comfortable single-strip doses in the low tens of milligrams. We plan up to about 250 mg of a single active only when it is soluble, bland, and heat-stable, and we say no to films above that.
| Active per strip | Expected strip mass | Loading (% dry weight) | What changes |
|---|---|---|---|
| < 1 mg | 100 to 120 mg | < 1 % | Homogeneity and content uniformity drive the program |
| 1 to 25 mg | 100 to 150 mg | 1 to 20 % | Standard program; flavor budget intact |
| 25 to 100 mg | 150 to 250 mg | 15 to 40 % | Heavier strip, slower dissolve, tighter masking budget |
| 100 to 250 mg | 250 to 300 mg | 40 to 80 % | Bland soluble actives only; consider two strips per serving |
| > 250 mg | not a film | n/a | Change format |
Dose is a mass budget
Polymer takes 50 to 65 % of the strip, plasticizer up to 20 % of polymer, sweetener and flavor a few percent more. Reviews report active loading of 5 to 30 % w/w; our strip window is 100 to 300 mg. The clearest commercial example is the buprenorphine/naloxone film: 8 mg sits at 17.2 % w/w in a 22.0 × 12.8 mm strip, and the 12 mg strength is cut 1.5 times longer rather than loaded harder. When the best-known film in the category scales dose by area, take the hint.
Ingredient properties decide more than the milligram number
Soluble, low-bitterness ingredients dissolve into the mass and dry clear. Insoluble powders must be suspended, and particle size shows up as grit, opacity, and content-uniformity scatter. Hygroscopic ingredients pull water into a film already at 4 to 7 % moisture. Heat-labile actives hold drying to the low end of 40 to 60 °C. The supplier's sheet (solubility, particle size, hygroscopicity, pH in solution) answers most feasibility questions before a film is cast.
Decision rules we actually use
Under 25 mg of a soluble active: standard strip, standard program. 25 to 100 mg: a heavier strip near 200 mg, thinner flavor budget, content uniformity on release. 100 to 250 mg: bland, soluble, heat-stable actives only, near the 300 mg ceiling, and a real conversation about two strips per serving. Above 250 mg: not a film. Bitter actives halve every threshold, because masking takes mass too. Below 1 mg the problem flips from space to homogeneity.
Strip size and serving plan are the levers
If the dose does not fit, the options in order of preference are two strips per serving, a longer strip, a lower label amount, or a more concentrated form of the ingredient. Each moves the label, carton count, and sachet, so the commercial owner should be in the room.
Worked example: two requests, one brand
A hypothetical brand, Marlow Daily, asks for vitamin D3 25 μg with methylcobalamin 500 μg. That is about 0.5 mg of actives in a 120 mg strip, 0.4 % w/w. Space is not the issue; distribution is, so release includes content uniformity by USP <905> (ten units, acceptance value not more than 15.0). A 25,000 IU vitamin D3 film showed bioavailability comparable to an oral solution in a published study, so the format is proven. Green light.
The second request is 200 mg elemental magnesium as glycinate. Glycinate is about 14 % magnesium, so the dose needs roughly 1.4 g of salt, five to ten strips of mass. We would offer 20 mg per strip or recommend another format, and say so at feasibility, not after a pilot.
What to bring to a feasibility review
Ingredient identities and suppliers, target amounts, the serving plan you can live with, flavor direction, claims, market, packaging concept, and any stability data. Name substitutes you would accept and label lines that cannot change.
Common questions
Yes, as long as the combined mass stays inside the tiers above and the actives are compatible in a wet water-based mass. Each extra active adds a potency assay to release.
Partly. Area scales linearly, but a larger strip needs a larger sachet and dissolves more slowly at the same thickness. We prefer two strips per serving over a strip much beyond 22 × 32 mm.
Primary sources
- Orodispersible Films: Current Innovations and Emerging Trends (Pharmaceutics, 2023, PMC10747242)
- SUBOXONE sublingual film prescribing information (FDA label, 2021)
- Pullulan and maltodextrin oral fast-dissolving films, Box-Behnken design (Pharmaceutics, 2022, PMC9146677)
- Orally disintegrating films: the effects of water content on disintegration and mechanical properties (J Drug Deliv Sci Technol, 2021)
- US 6,528,569, solid water-soluble or water-dispersible compositions (drying of cast films)
- USP <905> Uniformity of Dosage Units, FAQ
- FDA: Aspartame and Other Sweeteners in Food (relative sweetness table)
Formula feasibility, packaging, testing, claims, timing, and final quantities depend on the exact product. Use this guide to prepare better questions, then confirm the production plan for your project.