Primary service 04

Patches & Hydrogel Patches

Early-stage research support for topical patch, transdermal patch and hydrogel patch concepts. Dosage-form route definition and interpretation are provided directly; formulation, prototype and characterisation work is available by project, with study site, methods and responsible parties confirmed during feasibility review.

Discuss a patch project

01Dosage-Form Route
02Matrix & Adhesive
03Formulation & Prototypes
04Process & Characterisation
05Release & Delivery

Any module can be selected on its own, or combined into a staged route.

Product Goal & Dosage-Form Route

For projects deciding between patch formats, or unsure whether a patch is the right route at all.

Where this helps

You are deciding between a topical patch, transdermal patch and hydrogel patch.
You need to know whether a patch format suits your active and application site.
You need the development route and its principal risks defined before committing.

What we provide

Provided directly

Dosage-form route comparison against product goal and application site
Assessment of active and dose range suitability at a non-confidential level
Identification of principal technical, adhesion, loading and stability risks
Module selection and staged research roadmap

What you take away

Whether a patch format is realistic for this active and site
Which patch route to pursue, and why the others were set aside
Which risks govern feasibility, and in what order to resolve them

Possible outputs

Dosage-form route comparison · Feasibility note · Module selection and roadmap · Sample, method and responsibility list

What to send first

Non-confidential product concept and application site · Active class and approximate dose range · Target wear time and intended use · Existing materials, data or references

Scope. Advisory and planning work. A feasibility note does not commit LumiMicro to execute any subsequent module and gives no assurance of technical, regulatory or commercial outcome.

Matrix, Adhesive & Excipient Compatibility

For projects selecting a matrix or adhesive system and checking drug-loading compatibility.

Where this helps

You need a matrix or adhesive system selected for your active.
You are seeing crystallisation, migration or adhesion loss and need the cause narrowed.
You need to know which excipients are compatible before formulating.

What we provide

Provided directly

Screening design for matrix and adhesive candidates
Interpretation of compatibility observations and exclusion rationale

Available by project

Matrix, adhesive system and excipient candidate screening
Drug-loading compatibility and saturation behaviour observation
Appearance, crystallisation, migration and short-term change observation
Preliminary adhesion and cohesion suitability

What you take away

Which matrix and adhesive candidates remain viable
Whether the intended loading is compatible with the system
Which failure mode is driving the problem you are seeing

Possible outputs

Matrix and adhesive screening matrix · Compatibility observation records · Candidate range and exclusion rationale · Recommended formulation direction

What to send first

Active class and target loading at a non-confidential level · Intended patch format and wear time · Systems already tried and what was observed · Samples, where required, through an agreed route

Scope. Research-scale screening. Observations describe behaviour under the stated conditions and do not establish adhesion performance, stability or wear characteristics in a finished product.

Research-Scale Formulation & Prototypes

For projects that need research-grade patch formulations prepared and prototypes made.

Where this helps

You have a candidate matrix system and need research-grade patches prepared.
You need prototypes for downstream characterisation or delivery work.
You need numbered, allocated samples with traceable preparation records.

What we provide

Provided directly

Formulation route definition and critical step identification
Interpretation of preparation outcomes and recommended optimisation

Available by project

Research-grade patch formulation preparation
Research-scale batches, numbering and sample allocation
Appearance, uniformity, handling and packaging suitability observation
Small-range variable and repeatability observation

What you take away

Whether the formulation can be prepared reproducibly at research scale
Which preparation variables carry the greatest risk
The minimum experiments needed for the next round

Possible outputs

Research-scale patch prototypes or agreed samples · Preparation records and batch numbering · Preliminary process window · Risks, deviations and recommended next optimisation

What to send first

Candidate formulation at a non-confidential level · Target patch size, loading and quantity · Downstream use of the prototypes · Storage and shipping constraints

Scope. Research-scale prototypes are not sterile, GMP, clinical-batch, commercial-scale or saleable product. No process validation, batch release, scale-up or manufacturing readiness is implied.

Process Feasibility & Agreed Characterisation

For projects needing coating, forming, crosslinking or drying feasibility, and the physical attributes that matter to an early patch decision.

Where this helps

You need coating, film-forming, crosslinking, drying or forming feasibility assessed.
You need thickness, content uniformity, adhesion or rheology measured and compared.
You need preliminary stability and packaging observations under agreed conditions.

What we provide

Provided directly

Process route and characterisation plan design, with endpoint selection
Interpretation of results, including stated limitations

Available by project

Coating, film-forming, crosslinking, drying and forming feasibility
Appearance, thickness and content uniformity
Adhesion, peel, tack and cohesion assessment
Rheological and mechanical property assessment
Preliminary stability and packaging observation under agreed conditions

What you take away

Whether the process route is feasible at research scale
How the prototypes compare on the attributes that matter
Whether adhesion and uniformity support the intended wear time
Which attributes still need data before a conclusion can be drawn

Possible outputs

Process flow and feasibility records · Characterisation data tables and figures · Preliminary stability and packaging summary · Technical report stating method, model and limitations

What to send first

Prototypes or samples with storage conditions as agreed · Attributes and endpoints to be assessed · Any specification or reference targets · Existing data, if any

Scope. Results hold only within the stated specification, method and model. Preliminary stability observation is not a stability study to a recognised guideline and does not establish shelf life or wear performance in use.

Release, Delivery & Reporting Support

Optional. IVRT release and IVPT skin delivery evaluation for patch prototypes, plus external-development preparation and technical reporting.

Where this helps

You need release or skin delivery evidence for a patch prototype.
You are preparing an external development brief and need the technical content defined.
You have a report from another party and want it reviewed.

What we provide

Provided directly

Study design and endpoint selection for release or skin delivery work
External development brief preparation and vendor enquiry checklists
Review of data, protocols or reports produced by another party
Structuring of calculations, figures, limitations and next steps

Available by project

IVRT release and IVPT skin delivery evaluation, coordinated through the IVRT & IVPT service
Sample extraction and quantification, confirmed separately

What you take away

Whether the release or delivery profile supports the product concept
Whether an existing report's conclusions can be relied on
What an external development partner needs to receive to quote accurately
What evidence to add before the next decision

Possible outputs

Agreed study plan, results or data tables · External development brief · Vendor enquiry checklist · Structured technical report or report review note

What to send first

Prototypes or samples · The release or delivery question to be answered · Existing data or reports · Who will perform any analysis

Release and skin delivery work is run under our IVRT & IVPT Support service. Microneedle-based delivery is covered under Microneedle Development & Research Tools.

Scope. Analytical site, methods, suitability, validation status, quality system, raw data and report responsibility are confirmed per project. Does not constitute GLP/GMP, clinical, registration or regulatory acceptance, and implies no certainty of outcome.

Worked problems

How permeation data changes patch decisions

Two separate research examples show different uses of permeation data: relating in vitro flux to human exposure, and screening hydrogel-patch loading and coating thickness. Neither is a LumiMicro client project.

Can in vitro flux predict the plasma level a patch will give?

In vitro flux through human skin predicted 163.9 ng/mL; twenty volunteers gave 156.4—within 5%.

A drug with 10–30% oral bioavailability, a half-life of 0.8–2.8 h and three-times-daily dosing is a textbook transdermal candidate. MW 136, solubility 11 mg/mL, log P 2.3, m.p. 76–78 °C—the physicochemistry fits. The question is whether the skin can deliver a therapeutic dose.

Get the flux first, in vitro. Reservoir design: drug in a Carbopol gel reservoir, rate-controlling EVA membrane (28% VA, 51 µm), silicone pressure-sensitive adhesive, impermeable backing. Enhancers screened on rat skin; eucalyptus oil won—at 5%, flux 542.6 ± 49.7 µg/cm²/h, 4.5-fold over no enhancer (p < 0.01). The optimised patch across human epidermis: 346.0 ± 27.7 µg/cm²/h.

Size the patch from the flux. Steady-state plasma concentration = flux × area / clearance. With oral clearance 41.39 L/h and the target concentration: 20 cm², 250 mg.

Then into humans. Twenty healthy male volunteers, randomised, open-label, two-way crossover. Single dose: one patch vs four oral tablets. Multiple dose: one patch daily × 5 days vs two tablets three times daily × 5 days.

	Oral tablet	Patch
C_max (single / multiple)	1284 / 613.5 ng/mL	309 / 325 ng/mL
T_max	0.75 h	5 / 4 h
Steady-state C_min	near zero	131 ± 30.4 ng/mL
Mean residence time	—	5.2× longer
Steady-state daily AUC	3563.67 ng·h/mL	3753.91 ng·h/mL
Steady-state C_av	156.41 ± 40.31 ng/mL	148.48 ± 51.27 ng/mL

Human pharmacokinetics, patch vs oral tablets

One patch a day matched the exposure of three oral doses a day; peak a quarter of oral, trough lifted from zero to 131. No adverse events; no irritation or sensitisation.

Then close the loop. In vitro steady-state flux through human skin: 339.2 ± 17.4 µg/cm²/h, zero-order. C_ss = J_ss × A / CL predicts 163.9 ng/mL. Observed C_av in humans: 156.4 ± 40.3 ng/mL. Within 5%.

An in vitro/in vivo correlation is the hardest thing to obtain in transdermal development: it means release and permeation data can predict plasma levels, so a formulation change can be evaluated in vitro before deciding whether to return to the clinic. Most topical programmes stop at in vitro and animal data because there is no human dataset to correlate against. This one ran the whole road and obtained clinical trial approval along the way.

Published: Drug Deliv 2013;20(1):19–24, doi:10.3109/10717544.2012.742938 · Biol Pharm Bull 2013;36(6):931–937.

How can IVPT guide hydrogel-patch loading and coating thickness?

With nominal loading doubled, reported J rose from 1.52 to 15.51 µg/cm²/h; a separate thickness series also changed J.

The formulation question. Increasing drug per area and increasing coating thickness are not equivalent. A historical university-led report compared several nominal areal loads, then a separate series of coating thicknesses at a fixed nominal areal load, using excised rat dorsal skin.

Two separate screens. The report compared three nominal drug amounts per patch area, and separately compared three coating thicknesses while keeping nominal drug amount per area fixed. The reported flux values, J, are shown below to two decimal places.

Screen	Condition	J (µg/cm²/h)
Nominal loading	100 mg / 63 cm²	1.52
Nominal loading	150 mg / 63 cm²	4.46
Nominal loading	200 mg / 63 cm²	15.51
Coating thickness*	1.0 mm	2.71
Coating thickness*	1.2 mm	1.32
Coating thickness*	1.5 mm	1.00

Reported ex vivo rat-skin IVPT flux. The loading and thickness rows are separate screening series, not a joint-factor experiment; J values are rounded to two decimal places.

What the numbers mean. In this report, flux rose non-proportionally with nominal loading. At a fixed nominal amount per area, the thinner coating gave higher flux within the tested formulations. The thickness series also changed matrix mass and drug concentration, so the result does not establish a universal rule that thinner is better. *Nominal amount per area was held constant in the thickness series only.

What to decide next. Use IVPT to narrow loading and coating ranges, then check coating consistency, actual drug content per area and adhesion before advancing a prototype. The aim is a formulation that meets both delivery and physical requirements, not the maximum value of one variable.

Historical academic research, presented as a formulation-screening example rather than a LumiMicro client assignment. Ex vivo results do not establish human exposure, clinical equivalence or finished-product performance.

Ways to work with us

Three ways in, priced up front

Most projects start with one of these. Each has a fixed scope and a fixed price, so you know what you are buying before you write. The consultation can be paid by card; review and design are invoiced in USD or HKD by LumiMicro Life Sciences Limited, Hong Kong, payable by bank transfer.

One-hour consultation

USD 1,00060 minutes, video or phone

You have a compound, a formulation or a study result and one concrete question: which skin, which receptor fluid, which endpoint, why the result looks the way it does, whether to run the study at all.

You get

A direct answer, with the reasoning
The two or three things to check before spending more
A short written note the same day

Pay by card · USD 1,000 or ask a question first

Secure checkout by Stripe. Receipt and PDF invoice by email; we contact you within one working day to schedule.

Protocol or report review

USD 5,0003–5 working days

You have a protocol you are about to hand to a laboratory, or a report you have received and are not sure you can rely on—especially one that has drawn regulatory questions.

You get

Line-by-line review against the physics of skin transport, not only the guideline
Where the design cannot support the intended claim, and what would
A written opinion you can share internally or with your laboratory

Start with this

Study design

from USD 10,000scoped per project

You need a study designed from the compound outward—receptor system, model, endpoints, sample handling, acceptance criteria—ready for a laboratory to execute and a regulator to read.

You get

Feasibility assessment and design rationale
Full protocol with validation matrix and acceptance criteria
Laboratory briefing and, if needed, interpretation of the result

Start with this

Laboratory execution is arranged per project with a named study site; see the modules above. Regulated studies, clinical work and submissions are performed or reviewed by appropriately qualified providers—our part is the decision, the design and the interpretation.

Start with a non-confidential question.

Describe the patch concept, the stage the work has reached, and the decision the next round needs to support. Scope, responsibilities and delivery route are confirmed before work begins.

Discuss a patch project