
Chemical Name:Crisaborole
CAS:906673-24-3
Molecular Formula:C<sub>14</sub>H<sub>10</sub>BNO<sub>2</sub>
Molecular Weight:243.05 g/mol
Appearance:White to off-white crystalline powder
Melting Point:~190-195°C (dec.)
Solubility:- Water: Slightly soluble
- Organic solvents: Soluble in DMSO, methanol, ethanol
Pharmacological Class:Topical phosphodiesterase 4 (PDE4) inhibitor
Mechanism of Action:Inhibits PDE4, reducing pro-inflammatory cytokines (e.g., TNF-α, IL-17) and increasing anti-inflammatory mediators.
Indication:Mild-to-moderate atopic dermatitis (eczema) in patients ≥3 months old.
Chemical Structure :Boron-containing small molecule with a benzoxaborole core and a cyanovinylphenyl group. Key feature: Boron atom in a heterocyclic ring, enabling unique interactions with target enzymes.
Stability:Stable under recommended storage conditions (typically 20-25°C).

| Parameter | Specification | Test Method | Result |
|---|
| Appearance | White to off-white crystalline powder | Visual inspection | Complies |
| Identification | IR spectrum matches reference standard | USP <197> / FTIR | Complies |
| Assay (HPLC) | 98.0% - 102.0% (anhydrous basis) | USP <621> (Reverse-phase HPLC) | 99.5% |
| Related Substances | - Individual impurity ≤ 0.5% - Total impurities ≤ 1.5% | HPLC (USP <621>) | 0.3% (Max single) |
| Water Content (KF) | ≤ 0.5% w/w | Karl Fischer titration | 0.2% |
| Residual Solvents | - Methanol ≤ 3000 ppm - Others per ICH Q3C | GC (USP <467>) | <100 ppm |
| Heavy Metals | ≤ 10 ppm (as Pb) | USP <231> / ICP-MS | <5 ppm |
| Sulfated Ash | ≤ 0.1% | USP <281> | 0.05% |
| Particle Size | 90% particles ≤ 200 µm (if controlled) | Laser diffraction (USP <429>) | 150 µm (D90) |
| Microbial Limits | - TAMC ≤ 1000 CFU/g - TYMC ≤ 100 CFU/g | USP <61> | Complies |
| Boron Content | 4.2% - 4.6% (theoretical: 4.45%) | ICP-OES | 4.4% |
