Erythromycin Hydroalcoholic Solution 4% w/w

Cutaneous solution: Erythromycin Hydroalcoholic Solution 4% w/w. Additional appearance criteria are not established by the specific text reviewed. ^[1]

Topical antibiotic for acne according to the historical source. ^[1]

Erythromycin 90–115% of prescribed amount. ^[1]

Protect erythromycin raw material from light. ^[2]

No oxidative stability study of the finished mixture or inert-atmosphere requirement is provided. Use the source container. ^[1]

No quantitative hydrolytic stability limit is given for this formula. Retain the prescribed water amount and quality. ^[1]

Erythromycin is hygroscopic. ^[2]

For the finished product the source specifies:
Amber glass bottle; 15–25 °C.
Erythromycin raw material: the source specifies ≤30°C. This does not establish a BUD. ^{[1], [2]}

Erythromycin is unstable in acidic media. ^[2]

No complete compatibility test with added actives or alternative excipients is provided. Substitutions require separate evidence. ^[1]

Identity and weighing basis:
• Erythromycin: 4.40 g.
• Anhydrous citric acid: 0.4 g.
• Denatured ethanol 96% v/v, FTM grade: 50 g.
The specified chemical forms/grades belong to the exact source formula. ^[1]

Clean long-sleeved laboratory clothing, hair covering and gloves during handling; change gloves after contamination or damage.
Contain powder during weighing and trituration and use eye protection; select respiratory protection for the actual exposure. ^{[1], [3], [4]}

Reference batch: 100 g. First ingredient: Erythromycin, 4.40 g. Independently check chemical form, units and every scale conversion before weighing.
Verify chemical form and the w/w, w/v or v/v concentration basis against the formula. Do not equate g and mL without supported density. Check clarity/crystallisation and exact application route.
For the local assessment record quantity per preparation, work frequency, duration of open handling, potential exposure routes and effectiveness of controls. These are assessment inputs; no fictitious final risk score is assigned.
Volatile solvent in this formula: Denatured ethanol 96% v/v, FTM grade 50 g. Exclude ignition sources and minimise vapours/open evaporation. Check ventilation, electrical equipment and container compatibility with the specific solvent.
Release checkpoint: confirm final volume or mass at the reference temperature, intended clarity or dispersion, and specified container/closure. Do not equate grams and millilitres without a justified density. ^{[1], [2], [3], [4], [7], [9]}

Before mixing: verify each ingredient’s chemical form and lot, record theoretical amounts and check equipment cleanliness. Follow the temperatures and addition sequence in the procedure below. ^{[1], [4]}

Period reported by source: Historical validity: 2 months; in-use limit 2 months, within overall expiry.
This duration is a specific formulary/source instruction. This review did not verify a complete primary study establishing chemical, physical and microbiological extension for the same finished formulation.
Selected general rule: up to 35 days for an aqueous form appropriately preserved in its final composition and pH. Use 20–25 °C, or 2–8 °C only where permitted/required by the source and compatible with the dosage form. A preservative name is insufficient if it is diluted, inactivated or partitioned into another phase.
The reference-policy ceiling in this edition is the shorter of the source period above and the general ceiling. Extension needs matching active/excipients/strength, container, temperature, a stability-indicating method and the required microbiological evidence for aqueous extension. An applicable official USP–NF compounded monograph is assessed separately in its complete text.
Use-by date = the earliest allowed date from preparation plus selected period, ingredient expiries and any shorter supported limit. In-use dating never extends overall BUD. Complete the actual date for the batch after the required checks.
A default is a conservative dating limit, not experimental proof of batch stability. Its category depends on final composition, preservation and permitted temperatures. Water percentage or loss on drying does not determine aw. Document using SOP-014/F-006; use SOP-017/F-012 for specific aw evidence.
USP clarification: aw measurement is not required for every nonsterile preparation. Category assignment may use the exact composition and relevant representative examples; an uncertain or borderline formulation is best assessed by a suitable specific measurement. This edition contains no measured aw or released batch. The final preparation generally must not outlast the remaining BUD of its compounded bases/intermediates. An exception requires specific justification that physical, chemical and microbiological quality is not adversely affected. Record the final limit, intermediate preparation dates and their actual expiry dates separately. ^{[1], [5], [6], [8], [10]}

No separately registered base is required. Any commercial vehicle remains the exact named product in the formula table. ^[1]

Balance with suitable minimum weight, mortar/pestle or homogeniser, mixing vessels, spatulas, thermometer for heated processes and volumetric equipment for mL quantities. ^[1]

Dissolve erythromycin and citric acid in ethanol; make up to 100 g with freshly boiled and cooled water and homogenise. ^[1]

The 4.40 g charge includes 10% manufacturing overage for degradation; labelled strength remains 4%. ^[1]

Amber glass bottle. ^[1]

Erythromycin 90–115% of prescribed amount.
Record the method, acceptance criterion, actual result and reviewer separately in F-005. A critical specification failure requires quarantine and investigation under SOP-015; retesting needs justification. ^{[1], [9]}

Amber glass bottle; 15–25 °C. ^[1]

Dispense with a clear route, strength and use-by date. Complete amount per application and frequency from the prescription. ^[1]

Erythromycin Hydroalcoholic Solution 4% w/w
External use
Quantity: ____ Batch: ____
Prepared: ____ Use by: ____
Patient / dose / frequency: ____
Storage: Amber glass bottle; 15–25 °C.
Temperature for this batch BUD: ____ ^[1]

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.