General Information
Crisaborole Impurities and Crisaborole
Daicel Pharma synthesizes Crisaborole impurities of exceptional quality, such as 4-(4-(4-bromo-3-formylphenoxy)-3-formylphenoxy)benzonitrile, O-isomer of Crisaborole, 5-(3-cyanophenoxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaborole/m-Crisaborole, and so on. These impurities are crucial to assess the purity, reliability, and safety of Crisaborole, an active pharmaceutical ingredient. Besides, Daicel Pharma provides custom synthesis of Crisaborole impurities to meet clients’ demands for delivery worldwide.
The US FDA-approved Crisaborole [CAS: 906673-24-3] is a nonsteroidal anti-inflammatory PDE4 inhibitor for treating mild to moderate atopic dermatitis (AD) in patients aged two years and older.
Crisaborole: Use and Commercial Availability
Crisaborole is a phosphodiesterase-4 (PDE4) inhibitor that increases cyclic adenosine monophosphate (cAMP) levels and reduces inflammation. This nonsteroidal topical medication is utilized for treating mild to moderate atopic dermatitis (AD) and has shown efficacy in reducing itch in AD. Eucrisa is the brand name under which Crisaborole is available in the market.
Crisaborole Structure and Mechanism of Action 
The chemical name of Crisaborole is 4-((1-hydroxy-1,3-dihydrobenzo[c][1,2]oxaborol-5-yl)oxy)benzonitrile. Its chemical formula is C14H10BNO3, and its molecular weight is approximately 251.05 g/mol.
Crisaborole inhibits phosphodiesterase 4 (PDE-4), which increases cyclic adenosine monophosphate (cAMP) levels.
Crisaborole Impurities and Synthesis
During the synthesis1, storage, and handling of Crisaborole, impurities can form through various pathways such as side reactions, degradation, or contaminants in raw materials. It is necessary to analyze and control them to ensure the drug’s safety, efficacy, and quality. Common Crisaborole impurities include related substances, process-related impurities, and residual solvents. Analytical techniques like HPLC and LC are employed to detect and quantify these impurities, allowing their control within acceptable limits to maintain integrity.
Daicel Pharma offers a Certificate of Analysis (CoA) for Crisaborole impurity standards, such as 4-(4-(4-bromo-3-formylphenoxy)-3-formylphenoxy)benzonitrile, O-isomer of Crisaborole, 5-(3-cyanophenoxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaborole/m-Crisaborole, and so on, generated from an analytical facility compliant with cGMP standards. The CoA includes a comprehensive characterization report comprising data from techniques like 1H NMR, 13C NMR, IR, MASS, and HPLC purity2. Furthermore, on request, we give additional data like 13C-DEPT and CHN. Daicel Pharma can synthesize unknown Crisaborole impurities or degradation products. A complete characterization report accompanies every delivery.