Saturated boric acid otic solution in ethanol 70% — 5 g/100 mL charge · CGR-ES-092 (CGR-ES-092)

REFERENCE FORMULA

Reference formula

Reference basis: 100 mL, με 5 g αρχική φόρτιση / 100 mL with 5 g initial charge

Ingredient	Source quantity	Scaled quantity
Boric acid	5 g	—
Ethanol 70%	q.s. ad 100 mL	—

Prerequisite formulations

No separate prerequisite monograph is listed.

Documentation

Preparation description

Clear colourless otic solution in ethanol 70%. The source calls it saturated and filters after a 5 g boric acid charge. Any removed solid is absent from the finished solution; therefore an assayed 5% w/v strength cannot be assumed. ^{[1], [2]}

Action and use

The source describes antiseptic otic use for otitis externa, with two drops three times daily. Use requires clinical confirmation of an intact tympanic membrane and individual directions; it is not a wound-cleaning or middle-ear preparation. ^{[1], [2]}

Specifications

Use boric acid RFE 0001 and the source-specified ethanol 70%; the finished characteristic is a clear colourless solution. Record any filter residue and final volume. Actual dissolved content requires an appropriate assay if a numerical strength is claimed. ^{[1], [2], [6]}

Light

The source requires an opaque container and protection from light. Packaging must also support safe and unambiguous dispensing as an otic product. ^[1]

Air and oxidation

Tight closure and minimal open-vessel time during mixing/filtration limit ethanol evaporation. Changing the water–alcohol ratio can change solubility and actual strength. ^{[1], [2], [5]}

Water and solubility

Water is already present in the ethanol 70% vehicle. Do not substitute anhydrous ethanol or plain water. Despite the high alcohol content, no measured aw or challenge test is available for the exact finished solution. ^{[1], [5], [7]}

Humidity

The general procedure specifies relative humidity ≤60%. Keep the alcoholic vehicle closed and avoid composition changes from prolonged open handling. Contain boric acid dust during weighing. ^{[3], [6]}

Temperature

No heating is specified. Stir for one hour at a controlled, recorded working temperature because this is a saturation process. No numerical storage temperature is supplied; an added local 20–25 °C restriction away from ignition sources must be identified as such. ^{[1], [5], [6]}

pH and compatibility

No pH is specified for the hydroalcoholic solution. Weak acidity of aqueous boric acid does not define a numerical limit in ethanol 70%. Adjusting pH with alkali changes the formula. ^{[1], [2], [3]}

Other interactions

Boric acid incompatibilities include alkalis/carbonates/hydroxides, polyvinyl alcohol and tannins. Keep ethanol away from strong oxidisers. Do not empirically combine other ear drops in the same container. ^{[2], [3], [5]}

Ingredient-specific information

The active is H3BO3 (CAS 10043-35-3), not borax. Ethanol 70% describes the specified vehicle before dissolution, not an assayed finished alcohol content. Although the source mentions other alcohol strengths, this record is strictly restricted to the 70% vehicle. ^{[1], [2], [3], [5]}

Staff protection

Contain boric acid dust and wear gloves, goggles and a coat. Mix the alcoholic vehicle with suitable ventilation and no flames, sparks or unsuitable heating equipment. Include raw-material reproductive toxicity in the occupational assessment. ^{[3], [4], [5]}

Risk assessment

Not for children under 3, perforated tympanic membrane or ulcerated skin. Confirm otic rather than ophthalmic use. Absorption through damaged tissue and ingestion can cause systemic boric acid toxicity. Pregnancy, lactation and renal disease require clinical assessment; a small drop volume does not remove paediatric precautions. ^{[1], [2], [4]}

Compounding conditions

Use a 5.00 g boric acid charge and the specified vehicle on the 100 mL basis. Record temperature, one-hour stirring time, any undissolved residue and filtered yield. Filtering a saturated system does not prove quantitative dissolution. ^{[1], [6]}

BUD rationale

The source assigns three months in an opaque light-protective container, without a numerical temperature or complete stability study. With local adoption of this specific saturated system/process and controlled 20–25 °C storage, the ceiling is the earliest of 89 days, three calendar months and ingredient limits. This is not an established aw-based USP category or proven preservative efficacy. Confirm clarity, claimed potency where applicable, and packaging before adoption. 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], [7]}

Prerequisites

Required dependencies are an approved ethanol 70% vehicle, the solutions procedure and a local decision on strength labelling of the saturated product. No intermediate base or boric-water monograph is required. ^{[1], [6]}

Equipment

Balance suitable for 5 g, glass beaker with evaporation control, stirrer suitable for the flammable solvent, timer, thermometer, paper filter as specified and a compatible opaque otic container. ^{[1], [5], [6]}

Compounding method

1. Add the boric acid charge to the formula’s ethanol 70% vehicle. 2. Stir for one hour without heating and with evaporation control. 3. Filter through paper. 4. Record any solid and final yield, check clarity and package. Do not blindly replace filtration losses while assuming the entire charge remains dissolved. ^{[1], [6]}

Observations

Saturated, a 5 g initial charge, and a finished 5% w/v solution are not analytically identical statements. Avoid an unverified percentage-strength claim. Changing the vehicle within 60–96% ethanol creates a different solubility system and requires a separate record. ^{[1], [2]}

Container and packaging

Opaque, tightly closed otic drop container with materials compatible with ethanol 70%. The source specifies opacity but no particular polymer; verify closure/dropper compatibility and unambiguous otic labelling. ^{[1], [5], [6]}

Quality control

Verify vehicle, charge, mixing time, clarity, final volume/yield and filter record. A finished 5% w/v label requires a justified quantitative assay. The master supplies no ready assay method for this finished hydroalcoholic solution. ^{[1], [6]}

Storage

Keep tightly closed, protected from light and ignition, within the locally specified 20–25 °C range. Investigate turbidity or crystals; do not instruct the patient to heat the bottle. ^{[1], [5]}

Dispensing

Dispense only after confirming an appropriate otic indication and intact tympanic membrane. Explain use without touching the ear with the dropper, prohibition of swallowing and exclusion of children under 3. Pregnancy/lactation use requires clinician agreement. ^{[1], [4]}

Labelling

Saturated boric acid solution in ethanol 70% — FOR EAR USE ONLY. Not for eyes or swallowing. Do not use with a perforated eardrum or in children under 3. Dose as prescribed. Protect from light/ignition, tightly closed at 20–25 °C. Complete quantity, batch, preparation and authorised use-by dates during execution. ^{[1], [5]}

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

AEMPS, Formulario Nacional — ALCOHOL BORICADO (A SATURACIÓN) (FN/2003/PO/010)FN/2003 source identifier; current standalone official PDF accessed 2026-10-13PDF pp. 2–3; composition, specific method, storage, validity and patient leafletMaster composition, preparation and source-specific conditions. Independently written factual adaptation; not an official translation or endorsement. No laboratory testing performed for this document.2026-10-14
AEMPS — Ácido bórico (FN/2003/PA/007)FN/2003; standalone official PDF accessed 2026-10-13PDF p. 2Raw-material identity, physical properties, incompatibilities and route-specific precautions; raw-material assay limits are not finished-product specifications.2026-10-13
ILO/WHO International Chemical Safety Card 0991 — Boric acidApril 2014Identity; hazards/prevention; physical properties; chemical dangers; notesOccupational hazards of the identified raw material. Neat-material flash points and toxicity are not measured finished-mixture properties.2026-10-13
EMA — Boric acid and borate used as excipients: supporting report, Rev. 1EMA/CHMP/765436/2012 Rev.1, 11 November 2021; published 28 July 2022Summary; pharmacokinetics and dermal absorption; developmental/reproductive toxicity; pp. 3–6 and safety discussionBoron toxicology and exposure assessment. Excipient guidance does not itself establish an active topical product dose, BUD or an efficacy claim.2026-10-13
ILO/WHO International Chemical Safety Card 0044 — Ethanol (anhydrous)May 2018Identity; hazards/prevention; physical properties; chemical dangers; notesOccupational hazards of the identified raw material. Neat-material flash points and toxicity are not measured finished-mixture properties.2026-10-13
AEMPS — Elaboración de soluciones (PN/L/FF/007/00)Official FN procedure, version 00, accessed 2026-10-13Sections 5–6: environment, preparation, packaging, finished-product checksOfficial general dosage-form procedure; exact formula method takes precedence; batch-level tests are distinct from tests actually performed.2026-10-13
USP — Compounding Standards and Beyond-Use DatesNovember 2022 update, official USP fact sheet hosted by Mississippi Board of PharmacyNonsterile preparation BUD overview and category tableGeneral BUD framework; an AEMPS source period is not automatically a USP–NF monograph exception, and no measured water activity is implied.2026-10-13
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