Clarithromycin Impurity Standards

Clarithromycin impurity reference standards are used by pharmaceutical quality-control laboratories, contract research organisations, and generic drug manufacturers to identify, quantify, and control Clarithromycin-related impurities during analytical method development, method validation, and regulatory filing. As a macrolide antibiotic, Clarithromycin requires precise characterisation of its process impurities, degradation products, and related substances to meet European Pharmacopoeia (EP), United States Pharmacopeia (USP), and British Pharmacopoeia (BP) monograph requirements. Allmpus Laboratories manufactures and supplies a comprehensive library of Clarithromycin impurity standards, each provided with a Certificate of Analysis (COA) and Material Safety Data Sheet (MSDS). All products are held in-stock for rapid dispatch and are suitable for use in ANDA and DMF regulatory submissions.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

CLARITHROMYCIN EP IMPURITY A (USP) | CLARITHROMYCIN F

Chemical Name: 2-Demethyl-2-(hydroxymethyl)-6-O-methyle...

CAS No:
124412-58-4

Molecular Formula: C38H69NO14

Molecular Weight: 763.95

CAT No:
ALL-C04402

Keywords: SMILES string - C[C@@H]([C@@H]([C@H](C(...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY B (USP)

Chemical Name: 6-O-Methyl-15-norerythromycin A

CAS No:
299409-85-1

Molecular Formula: C37H67NO13

Molecular Weight: 733.93

CAT No:
ALL-CLA-1140-1

Keywords: Clarithromycin Impurity

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY C

Chemical Name: 6-O-Methylerythromycin A (E)-9-oxime

CAS No:
103450-87-9 | 127253-06-9

Molecular Formula: C38H70N2O13

Molecular Weight: 762.97

CAT No:
ALL-C03418

Keywords: SMILES string - C[C@@](OC)(C[C@H](/C([C...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY D

Chemical Name: 3″-N-Demethyl-6-O-methylerythromycin A

CAS No:
101666-68-6

Molecular Formula: C37H67NO13

Molecular Weight: 733.93

CAT No:
ALL-C03419

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@...

Inventory Status:IN STOCK/08-174

COA MSDS

CLARITHROMYCIN EP IMPURITY E (USP) | 6,11-DI-O-METHYLERYTHROMYCIN A

Chemical Name: 6,11-Di-O-methylerythromycin A

CAS No:
81103-14-2

Molecular Formula: C39H71NO13

Molecular Weight: 761.98

CAT No:
ALL-C03420

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY F

Chemical Name: 6,12-Di-O-methylerythromycin A

CAS No:
128940-83-0

Molecular Formula: C39H71NO13

Molecular Weight: 761.98

CAT No:
ALL-C04299

Keywords: SMILES string - CCC1C(C(C(C(=O)C(CC(C(C...

Inventory Status:Delivery 3-4 weeks (Custom Synthesis)

COA MSDS

CLARITHROMYCIN EP IMPURITY G

Chemical Name: (3R,4S,5S,6R,7R,9R,10E,11S,12R,13S,14R)-...

CAS No:
127182-44-9

Molecular Formula: C39H72N2O13

Molecular Weight: 776.99

CAT No:
ALL-C03421

Keywords: SMILES string - CCC1C(C(C(C(=NOC)C(CC(C...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY H (USP)

Chemical Name: N-[(2S,3R,4S,6R)-2-[[(3R,4S,5S,6R,7R,9R,...

CAS No:
127140-69-6

Molecular Formula: C38H67NO14

Molecular Weight: 761.94

CAT No:
ALL-C03422

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY I (USP)

Chemical Name: (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-6-[4...

CAS No:
118058-74-5

Molecular Formula: C30H55NO10

Molecular Weight: 589.76

CAT No:
ALL-C03423

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY J (USP)

Chemical Name: (3R,4S,5S,6R,7R,9R,11S,12R,13S,14R,E)-6-...

CAS No:
13127-18-9 / CAS NO.: 111321-02-9

Molecular Formula: C37H68N2O13

Molecular Weight: 748.94

CAT No:
ALL-C03424

Keywords: SMILES string - C[C@H]([C@H]([C@](O)(C[...

Inventory Status:IN STOCK/08-180

COA MSDS

CLARITHROMYCIN EP IMPURITY N

Chemical Name: (10E)-10,11-Didehydro-11-deoxy-6-O-methy...

CAS No:
144604-03-5

Molecular Formula: C38H67NO12

Molecular Weight: 729.94

CAT No:
ALL-C03428

Keywords: SMILES string - C[C@@](OC)(C[C@H](C(/C(...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN EP IMPURITY O

Chemical Name: (3R,4S,5S,6R,7R,9R,11S,12R,13S,14R,Z)-6...

CAS No:
127252-80-6

Molecular Formula: C39H72N2O13

Molecular Weight: 776.99

CAT No:
ALL-C03429

Keywords: SMILES string - C[C@@](OC)(C[C@H](/C([C@...

Inventory Status:IN STOCK/08-185

COA MSDS

CLARITHROMYCIN EP IMPURITY R

Chemical Name: (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-14-E...

CAS No:
992-62-1

Molecular Formula: C36H65NO13

Molecular Weight: 719.9

CAT No:
ALL-CAL-R

Keywords: SMILES string - C[C@@H]([C@@H]([C@H](C(...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN IMPURITY

Chemical Name: (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-6-(...

CAS No:
81103-11-9

Molecular Formula: C38H69NO13

Molecular Weight: 747.95

CAT No:
ALL-C03822

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@...

Inventory Status:IN STOCK/08-189

COA MSDS

CLARITHROMYCIN IMPURITY P

Chemical Name: (3R,4S,5S,6R,7R,9R,11R,12R, 13S,14R)-4-(...

CAS No:
123967-58-8

Molecular Formula: C39H71NO13

Molecular Weight: 761.98

CAT No:
ALL-CAL-P

Keywords: SMILES string - C[C@@](OC)(C[C@H](C([C@@...

Inventory Status:Delivery 3-4 weeks (Custom Synthesis)

COA MSDS

CLARITHROMYCIN USP IMPURITY K

Chemical Name: (1S,2R,5R,6S,7S,8R,9R,Z)-8-(((2S,3R,4S,...

CAS No:
127157-35-1

Molecular Formula: C30H51NO8

Molecular Weight: 553.73

CAT No:
ALL-C03425

Keywords: SMILES string - C[C@@](OC)(C/C(C)=C1O[C...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN USP IMPURITY L

Chemical Name: (3R,4S,5S,6R,7R,9R,11S,12R,13S,14R,Z)-6-...

CAS No:
127253-05-8

Molecular Formula: C38H70N2O13

Molecular Weight: 762.97

CAT No:
ALL-C03426

Keywords: SMILES string - C[C@@](OC)(C[C@H](/C([C...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN USP IMPURITY M

Chemical Name: (3R,4S,5S,6R,7R,9R,11S,12R,13S,14R,E)-14...

CAS No:
127182-43-8

Molecular Formula: C37H68N2O13

Molecular Weight: 748.94

CAT No:
ALL-C03427

Keywords: SMILES string - O=C([C@H](C)[C@@H](O[C@...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

CLARITHROMYCIN USP IMPURITY Q

Chemical Name: 6-O-Methyl Erythromycin N-Oxide

CAS No:
118074-07-0

Molecular Formula: C38H69NO14

Molecular Weight: 763.95

CAT No:
ALL-CAL-Q

Keywords: Clarithromycin EP Impurity Q, 6-O-Methyl...

Inventory Status:DELIVERY IMMEDIATE

COA MSDS

Key Clarithromycin Impurity Variants

Clarithromycin EP Impurity A (USP) — a specified process-related impurity recognized under both the Ph. Eur. and USP monographs for clarithromycin
Clarithromycin EP Impurity B (USP) (CAS 299409 — 85-1; 6-O-Methyl-15-norerythromycin A)-a demethylated, nor-analogue impurity controlled in both pharmacopeial monographs
Clarithromycin EP Impurity E / USP Related Compound A (CAS 81103 — 14-2; 6,11-Di-O-methylerythromycin A)-an over-methylated positional isomer relevant to confirming resolution from the main peak
Clarithromycin EP Impurity H (USP) — a specified related substance used in method specificity and stability studies
Clarithromycin USP Impurity L (Clarithromycin (Z) — 9-oxime)-an oxime degradation product relevant to forced-degradation and stability-indicating method validation
Additional EP/USP — designated impurities are available on request to support full impurity-profile coverage for regulatory submissions.

Allmpus's Capability for This Drug Family

Allmpus Laboratories manufactures and supplies a broad set of clarithromycin-related impurities, including multiple EP- and USP-designated variants (Impurity A, B, H, and USP Impurity L among them), reflecting established capability in macrolide antibiotic impurity synthesis and isolation. Because clarithromycin impurities often differ from the parent structure by a single methyl group, hydroxyl position, or oxime substitution, isolating and confirming these species requires preparative purification techniques capable of resolving closely related macrolide structures. Each compound is released with a Certificate of Analysis comprising ¹H NMR, ¹³C NMR, mass spectrometry, HPLC purity, IR, and TGA data, supporting customers' method validation, impurity qualification, and regulatory documentation requirements. Allmpus's R&D and manufacturing operations, based in Maharashtra, India, support API manufacturers, generic drug developers, and contract research organizations sourcing clarithromycin-related reference standards for QC testing and DMF/ANDA support work.

Frequently Asked Questions

Why are some clarithromycin impurities shared between the EP and USP monographs?

Clarithromycin impurities such as Impurity A and Impurity B are recognized under both pharmacopeial systems because the same process-related substances arise consistently during the erythromycin-to-clarithromycin synthetic route, so both monographs control them using aligned (though not always identically numbered) designations.

What is the difference between Clarithromycin EP Impurity B and Impurity E?

Impurity B (6-O-Methyl-15-norerythromycin A) is a demethylated nor-analogue, while Impurity E (6,11-Di-O-methylerythromycin A) is an over-methylated isomer-the two arise from opposite directions of incomplete versus excessive methylation during synthesis.

Why is the (Z)-9-oxime impurity relevant to clarithromycin stability testing?

The 9-oxime degradation product (USP Impurity L) can form under certain storage or synthetic conditions, so it is used as a reference standard in forced-degradation studies to confirm that stability-indicating HPLC methods can detect this specific degradation pathway.