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CGR-ES-081 / EDITION 10.0

Salicylic acid and lactic acid collodion

Film-forming cutaneous liquid · Spain · AEMPS

2026-10-14Reference document · Local adoption required

Collection and scientific editing: Stasinos Chr. SikaliasContent edition: 10.0Record editorial review date: 2026-10-14

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REFERENCE FORMULA

Reference formula

Reference basis: Source nominal 25 g batch; retain separately specified masses and volumes

IngredientSource quantityScaled quantity
Salicylic acid2.5 g—
Lactic acid, compendial grade2.5 g—
Ethanol 96%0.5 mL—
Diethyl ether0.5 mL—
Flexible collodion19 g—

Prerequisite formulations

No separate prerequisite monograph is listed.

Documentation

Preparation description
Clear viscous liquid leaving a film after solvent evaporation. Source calls the batch 25 g but uses mixed units; do not infer an exact final w/w percentage or volume. [1]
Action and use
Local keratolysis for common/plantar warts or specified hyperkeratoses. Confirm lesion diagnosis; do not apply to moles or suspicious pigmented lesions. [1]
Specifications
Complete salicylic-acid dissolution, clear viscous product, no foreign particles and functional closure/applicator. No numeric final viscosity, solvent-content or API-assay limits are published. [1]
Light
Use amber glass and protect from light. Air/light favour peroxide formation in ether raw material; follow the laboratory solvent monitoring/retirement programme. [1], [2]
Air and oxidation
Minimise open time and close promptly: ether/ethanol loss changes composition and film viscosity. Do not replace evaporated solvent empirically. [1], [2]
Water and solubility
No added water is listed; water may enter through the specified compendial materials. Do not dilute with water or change the acid/collodion grade. [1]
Humidity
Effective closure limits solvent-composition changes. No room-humidity limit or measured aw is supplied; apparently nonaqueous character does not support a 180-day assignment. [1]
Temperature
Mix without heating. Store below 20 °C as the source requires, away from heat/ignition. Ether is highly volatile and flammable. [1], [2]
pH and compatibility
No validated pH method/range is supplied for this volatile system. Treating it as an aqueous solution is not an equivalent test; do not neutralise its acids. [1]
Other interactions
Segregate ether from oxidisers. Check whether the selected collodion contains colophony relevant to contact allergy; flexible collodions are not assumed compositionally identical. [2], [3]
Ingredient-specific information
The acids supply keratolysis and collodion forms the film. The 2.5 g lactic acid refers to RFE 0458 material at its specified strength, not an assumed 2.5 g anhydrous acid. Weigh 19 g collodion; do not measure 19 mL. [1]
Staff protection
Use extraction suitable for flammable solvents, goggles, coat and compatible gloves. Exclude flame, sparks and heating. Manage ether under the approved peroxide-control programme; do not concentrate aged residues. [2], [4]
Risk assessment
Major risks: ignition, vapours, acid injury to healthy skin and g/mL confusion. Avoid face, genital sites, mucosa and inflamed/infected skin; source contraindicates use below 2 years. Diabetes, peripheral circulation problems and extensive lesions require specific clinical assessment. [1], [3]
Compounding conditions
Prefer compounding in the final amber bottle to limit losses. Scale every listed component proportionally, keeping g and mL separate; do not arbitrarily make up to 25 g or 25 mL. [1]
BUD rationale
The exact monograph specifies 1 month in tightly closed amber glass below 20 °C, light-protected. Reference ceiling is 28 days and no later than 1 calendar month under those conditions. No independent exact-formulation/container study was retrieved. Duofilm industrial shelf life does not transfer. Editorial convention: calendar-month source periods are retained as calendar periods; the calendar-period conversion ceiling is 28 days for one month or 89 days for three months; a separately selected shorter ceiling still governs. It is a conservative conversion, not a source quotation. [1], [3]
Prerequisites
Qualified pharmaceutical flexible collodion with documented composition is required. CGR-BP-033 is a separate compendial base to assess, not automatically the identical AEMPS input. [1]
Equipment
Balance, amber bottle, suitable calibrated device for 0.5 mL ether/ethanol and gentle mixing. Measure collodion gravimetrically, not in an open volumetric cylinder. [1]
Compounding method
Place 2.5 g salicylic acid and 2.5 g lactic acid in the amber bottle. Add 0.5 mL ethanol 96% and 0.5 mL ether and mix. Weigh 19 g flexible collodion directly into that bottle. Close and mix to complete dissolution without heating or prolonged air exposure. [1], [2]
Observations
Do not treat nominal 25 g as an exact theoretical mass without the actual material grades/densities. Record final mass and yield; material solvent loss requires rejection/investigation. [1]
Container and packaging
Amber glass bottle with solvent-compatible tight closure; an integrated brush or spatula supports localised application. [1]
Quality control
Verify quantities, clarity and dissolution; locally assess film formation on a suitable inert test surface. Check closure and applicator function. Visual inspection does not establish active content. [1]
Storage
Keep tightly closed and protected from light below 20 °C, away from ignition sources. Follow local flammable-liquid storage requirements. [1], [2]
Dispensing
Apply only to the diagnosed lesion; protect adjacent skin with soft paraffin as in the source. Avoid vapour inhalation, smoking and flame during/after use. Follow prescribed frequency and duration. [1], [3]
Labelling
Salicylic/lactic acid collodion · EXTERNAL USE ONLY · FLAMMABLE. Apply to lesion__. Close immediately. Store below 20 °C, away from light/flame/children. Batch__/Prepared__/Use by__. [1], [2]
v9_controls
The numeric value is a literature reference ceiling subject to its specific conditions. No actual batch BUD has been assigned and no aw measurements have been produced. The exact formula, prerequisites, container, storage and quality evidence require approval for the actual application. The BUD clock starts when compounding begins. Use the shortest applicable supported limit and assess in-use dating separately. USP categories are a technical framework and are not presented as Greek legislation.

Sources and references

  1. AEMPS — Formulario Nacional — FN/2003/FMT/006 COLODIÓN CON ÁCIDO SALICÍLICO Y ÁCIDO LÁCTICOCurrent AEMPS standalone PDF; code FN/2003/FMT/006PDF p 2 §§3–7; subsequent safety and patient informationExact formulation, process, source shelf life and formulation-specific precautions; independent factual compilation, not official translation.2026-10-14
  2. CDC/NIOSH Pocket Guide — Ethyl etherPage reviewed 30 October 2019; retrieved 13 October 2026CAS 60-29-7; incompatibilities, fire risk, exposure and protectionDiethyl ether raw-material hazards; no finished-product stability/BUD claim.2026-10-13
  3. Thornton & Ross — Duofilm SmPCText revised 25 June 2021; retrieved 13 October 2026§§4.3–4.6 and 6.1Primary authorised product information for a different salicylic/lactic collodion. Corroborates local toxicity precautions; composition, dose, shelf life and solvent percentage are not transferred.2026-10-13
  4. CDC/NIOSH Pocket Guide — Ethyl alcoholPage reviewed 30 October 2019; retrieved 13 October 2026Flammability, incompatibilities and personal protectionEthanol raw-material handling; not a measured flash point or hazard classification of the finished mixture.2026-10-13
  5. USP — General Chapter <795> Frequently Asked QuestionsNovember 1, 2023 FAQ; rechecked 14 October 2026Questions 52, 54–56, 61, 64–66General category/extension rules only; not exact-product stability evidence.2026-10-14