Paroxetine Hydrochloride Anhydrous API is the anhydrous hydrochloride salt of Paroxetine, a selective serotonin reuptake inhibitor (SSRI) pharmaceutical active ingredient. Paroxetine Hydrochloride is chemically identified as (3S,4R)-3-[(1,3-benzodioxol-5-yloxy)methyl]-4-(4-fluorophenyl)piperidine hydrochloride and is used as the active pharmaceutical ingredient in pharmaceutical formulations of Paroxetine.
A key point for API identification is that Paroxetine Hydrochloride Anhydrous is different from Paroxetine Hydrochloride Hemihydrate. The anhydrous form has CAS Number 78246-49-8, molecular formula C19H20ClFNO3, and molecular weight 365.83 g/mol. The hemihydrate form has CAS 110429-35-1, formula C19H20FNO3·HCl·½H2O, and molecular weight 374.83 g/mol. The USP monograph explicitly recognizes both forms and requires the material to be identified as anhydrous or hemihydrate.
The USP definition specifies an assay range of 98.5% to 102.0%, calculated on the anhydrous and solvent-free basis. For the anhydrous form, USP specifies water content of not more than 1.5%.
This distinction is particularly important for pharmaceutical API databases and CMS product pages.
Paroxetine HCl Anhydrous
Paroxetine HCl Hemihydrate
FDA and USP records clearly distinguish these two forms.
Paroxetine is an SSRI pharmaceutical ingredient used in products indicated for several psychiatric conditions. Paroxetine hydrochloride products have been used in the treatment of major depressive disorder, panic disorder, social anxiety disorder and premenstrual dysphoric disorder, depending on the approved product and jurisdiction.
Paroxetine works primarily by inhibiting the serotonin transporter, increasing serotonin availability in the synaptic space. The active pharmaceutical ingredient is therefore subject to stringent controls for chemical identity, stereochemical integrity, assay and related substances.
The USP monograph provides comprehensive analytical controls for Paroxetine Hydrochloride. Identification includes infrared spectroscopy, chloride identification and chromatographic identity. The assay is performed by HPLC. The USP assay specification is 98.5–102.0% on the anhydrous and solvent-free basis.
The monograph also controls specific related substances. Depending on the applicable chromatographic procedure, limits include Paroxetine Related Compound B, C, F and G, together with unspecified impurities and total impurities. These controls are important because the API contains a stereochemically defined pharmaceutical substance and manufacturing-related impurities must remain within validated limits.
A qualified Paroxetine HCl Anhydrous API Manufacturer in India should maintain strict control over synthesis, purification, crystallization and drying to consistently produce the anhydrous form.
The final drying process is particularly important because absorption of moisture can affect the hydrate state. USP specifies that the anhydrous form should be preserved in tight containers, while the hemihydrate has separate packaging requirements.
Quality documentation for Paroxetine HCl Anhydrous API can include a Certificate of Analysis, specification sheet, chromatographic purity data, residual-solvent information, water-content results, stability information and applicable regulatory documentation.
Important analytical parameters for Paroxetine HCl Anhydrous include:
The USP monograph specifies residue on ignition NMT 0.1% and heavy metals at 0.002%, equivalent to 20 ppm. Water for the anhydrous form is NMT 1.5%.
Paroxetine Hydrochloride Anhydrous should be protected from moisture and stored in tight containers. The USP specifically distinguishes the storage requirements of the anhydrous and hemihydrate forms.
For pharmaceutical manufacturing, storage and packaging should be based on validated stability data and the applicable approved specification.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.5% |
| Residue on Ignition | NMT 1.0% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.5% |
| Melting Point | 116–120°C |