Diphenylpyraline is a synthetic first-generation H1 antihistamine and pharmaceutical active ingredient. It is used for the symptomatic management of allergic conditions by reducing the effects of histamine at H1 receptors.
Diphenylpyraline is identified by CAS No. 147-20-6. Its molecular formula is C17H21N and its molecular weight is approximately 239.36 g/mol.
Diphenylpyraline is an alkylamine-type antihistamine with antiallergic properties. It acts primarily as an antagonist at histamine H1 receptors, helping reduce histamine-mediated symptoms such as itching, redness and allergic skin reactions.
Diphenylpyraline blocks histamine activity at peripheral H1 receptors. As a first-generation antihistamine, it can also produce central nervous system effects and may cause drowsiness.
Diphenylpyraline competitively antagonizes H1 histamine receptors. By reducing histamine activity at these receptors, it decreases histamine-mediated effects including increased vascular permeability, itching and smooth-muscle responses.
Diphenylpyraline has been used in pharmaceutical preparations for symptomatic relief of:
Approved uses and regulatory status vary by country and pharmaceutical product.
Diphenylpyraline is relevant to pharmaceutical manufacturers and formulation-development organizations working on antihistamine and antiallergic formulations.
The API may be incorporated into appropriate pharmaceutical dosage forms according to the approved formulation and applicable regulatory requirements.
Diphenylpyraline API quality evaluation may include:
Testing should be performed using validated analytical methods appropriate for the API and intended formulation.
Diphenylpyraline intended for pharmaceutical manufacturing should comply with applicable GMP, quality-control and regulatory requirements.
The final API specification should be established according to the intended market, applicable pharmacopoeial requirements and the manufacturer's approved product specification.
A batch-specific Certificate of Analysis (CoA) should provide relevant analytical results and acceptance criteria.
Diphenylpyraline API should be stored in tightly closed, appropriately labelled containers under the manufacturer's recommended storage conditions. Protection from excessive heat, moisture and unsuitable environmental exposure should be maintained.
Diphenylpyraline is relevant to pharmaceutical companies developing and manufacturing antihistamine and antiallergic pharmaceutical products.
For commercial applications, customers should verify the API identity, chemical form, grade, assay, purity, impurity profile, regulatory documentation and batch-specific CoA before use.
Consistent Diphenylpyraline API quality is important for reliable formulation development and pharmaceutical manufacturing. Control of identity, assay, purity and related substances supports reproducible product quality.
Appropriate documentation may include a Certificate of Analysis, specification sheet, safety documentation and applicable regulatory information.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | NLT 98.0% by HPLC |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 5.5 – 6.5 |
| Individual Impurity | NMT 1.0% |
| Total Impurities | NMT 2.0% |
| Water Content | NMT 1.0% |
| Melting Point | 150°C – 154°C |