Framycetin Sulfate 4146-30-9

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Product Information

Product name	Framycetin Sulfate； Neomycin B sulfate； Fradiomycin B sulfate
CAS No.	4146-30-9
Molecular Formula	C₂₃H₅₂N₆O₂₅S₃
Molecular Weight	908.88
Quality Standard	EP11

COA

Test Items	Specifications	Results
Appearance	White or yellowish-white powder, Hygroscopic	Yellowish-white powder, Hygroscopic
Solubility	Freely soluble in water, very slightly soluble in ethanol (96 per cent), practically insoluble inacetone	Conforms
Identification	Examine the chromatograms obtained in the test for related substances. Results: -the retention time of the principal peak in the chromatogram obtained with the test solution is approximately the same as that of the principal peak in the chromatogram obtained with reference solution (a), - it complies with the limit given for impurity C.	Conforms
Identification	It gives reaction (a) of sulfates	Conforms
pH	6.0 - 7.0	6.3
Specific optical rotation	+52.5°~ +55.5°	+52.6°
Loss on drying	≤8.0%	6.5%
Sulfate	27.0% - 31.0%	28.2%
Sulfated ash	≤1.0%	0.6%
Residual substances	Impurity A ≤1.0%	0.10%
	Impurity C ≤3.0%	0.8%
	Total other impurities ≤3.0%	< 1.0%
Assay	≥ 630 IU/mg (dried substance)	759 IU/mg
Bacterial endotoxins	≤1.3 IU/mg	Conforms
Microbial limits	TAMC ≤10³ cfu/g	<10cfu/g
Microbial limits	TYMC ≤10²cfu/g	<10cfu/g
Particle size	D10μm	15μm
	D50μm	62μm
	D90μm	168μm
Conclusion	It conforms to EP11 quality standard.

Usage

Framycetin Sulfate (CAS 4146-30-9)— An Aminoglycoside for Topical, Ophthalmic and ENT Formulations

Framycetin sulfate is the sulfate of neomycin B, an aminoglycoside produced by selected strains of Streptomyces fradiae or Streptomyces decaris. It is the principal and most pharmacologically active component of the neomycin complex — supplied not as a variable fermentation mixture, but as a purified single-entity API with pharmacopoeially defined composition and potency.

1. Mechanism: bactericidal and rapid

Like other aminoglycosides, framycetin binds the 30S ribosomal subunit — specifically the 16S rRNA and the S12 protein — blocking mRNA reading, inducing misreading and translational frameshift, and causing premature termination. The result is bactericidal rather than bacteriostatic activity, which is the clinically relevant property for superficial skin, wound, ocular and aural infections where bacterial load must be reduced quickly.

2. Spectrum and established clinical use

Framycetin sulfate is active against a wide range of Gram-positive and Gram-negative organisms implicated in superficial infections, including staphylococci (including strains resistant to other antibiotics), Pseudomonas aeruginosa, coliform bacteria and pneumococci. Established formulations and use concentrations:

Application	Typical concentration	Indications
Skin cream / ointment	1%	Superficial bacterial skin infections, burns, wounds, pyoderma, impetigo, folliculitis, infected eczema and ulcers
Eye drops / ointment	0.50%	Bacterial conjunctivitis, blepharitis, styes, corneal abrasions and burns; prophylaxis after foreign-body removal
Ear / nasal (often combined)	0.50%	Otitis externa; used with gramicidin and dexamethasone in combination ENT preparations

Regulatory product information for ophthalmic framycetin preparations notes that the substance is exceptionally well tolerated by ocular tissues and that the preparations are non-irritant — a relevant point for ophthalmic formulators selecting between aminoglycosides.

3. Why framycetin sulfate outperforms generic neomycin sulfate

This is the core commercial argument, and it is a composition argument, not a marketing one — which is exactly why it withstands scrutiny from QA and regulatory reviewers.

Dimension	Framycetin Sulfate	Neomycin Sulfate USP/EP
Composition	Purified single entity (neomycin B)	Variable mixture of neomycin B, neomycin C and neamine (neomycin A)
Neomycin C limit	≤3% (Ph.Eur.)	Not controlled to the same limit
Neomycin A (neamine) limit	≤1%	Present as a constituent
Potency basis	≥630 IU/mg (dried substance)	Expressed against the mixed complex
Relative activity	Neomycin B is the most active stereoisomer; supplier and aminoglycoside literature reports roughly 65% greater activity than neomycin C and about 90% greater than neomycin A	Diluted by less active stereoisomers
Batch-to-batch reproducibility	Composition defined, so potency is reproducible	Stereochemical variability translates into variable antimicrobial performance