Protriptyline Hydrochloride is the hydrochloride salt of protriptyline, a tricyclic antidepressant belonging to the dibenzocycloheptene class. It is an established pharmaceutical active ingredient used in the manufacture of formulations containing protriptyline hydrochloride. The API has the molecular formula C19H21N·HCl and a molecular weight of 299.84 g/mol. Its CAS Number is 1225-55-4. The USP identifies Protriptyline Hydrochloride under the chemical name 5H-Dibenzo[a,d]cycloheptene-5-propanamine, N-methyl-, hydrochloride.
Protriptyline Hydrochloride is generally described as a white to yellowish crystalline powder or powder. Official U.S. labeling describes the substance as freely soluble in water and soluble in dilute hydrochloric acid.
The API is the hydrochloride salt of the secondary amine protriptyline. PubChem identifies Protriptyline Hydrochloride as the hydrochloride salt form of protriptyline and reports a molecular weight of approximately 299.8 g/mol.
Product Name: Protriptyline Hydrochloride
CAS Number: 1225-55-4
Molecular Formula: C19H21N·HCl
Molecular Weight: 299.84 g/mol
Chemical Class: Tricyclic antidepressant / dibenzocycloheptene derivative
API Form: Hydrochloride salt
Appearance: White to yellowish powder
Solubility: Freely soluble in water; soluble in dilute hydrochloric acid
Pharmacopoeial Reference: USP
The USP monograph defines Protriptyline Hydrochloride as containing NLT 99.0% and NMT 101.0%, calculated on the dried basis. The current USP revision also includes infrared identification, UV identification, chloride identification and X-ray powder diffraction.
Protriptyline Hydrochloride is used as the active pharmaceutical ingredient in protriptyline-containing pharmaceutical formulations. Official DailyMed labeling identifies it as an antidepressant agent and describes it as a dibenzocycloheptene derivative.
Protriptyline is a tricyclic antidepressant whose pharmacological activity is associated primarily with effects on monoamine neurotransmitter reuptake. Pharmaceutical formulations containing Protriptyline Hydrochloride have historically been supplied as oral tablets, including 5 mg and 10 mg strengths.
For API manufacturers, appropriate control of chemical identity, assay, moisture, inorganic residue, pH and other applicable quality characteristics is important for maintaining consistent pharmaceutical quality.
The current USP-based specification defines Protriptyline Hydrochloride at 99.0–101.0% on the dried basis. Importantly, the USP API assay is a titrimetric assay using 0.1 N perchloric acid, rather than an HPLC assay. Therefore, the CMS field "Assay (HPLC)" should not incorrectly describe the USP titration as HPLC.
USP identification includes infrared spectroscopy, UV-visible spectroscopy at 292 nm, chloride identification and X-ray powder diffraction.
The USP 2025-based monograph specifies Residue on Ignition NMT 0.1%, pH 5.0–6.5 using a 10 mg/mL aqueous solution, and Loss on Drying NMT 0.3%, with drying under reduced pressure at 60°C to constant weight.
Protriptyline Hydrochloride API manufacturing requires controlled processing, appropriate raw-material qualification, validated analytical testing and batch-to-batch consistency. Quality control programs may include identity confirmation, assay determination, moisture evaluation, residue testing, pH determination and impurity assessment according to the applicable specification.
Pharmaceutical customers may require documentation supporting the identity, purity and quality of each batch. Specifications can be aligned with applicable USP requirements or with approved customer and regulatory specifications.
Protriptyline Hydrochloride should be protected from unsuitable environmental conditions and packed in appropriate well-closed containers. The USP monograph specifies preservation in well-closed containers.
Appropriate packaging and controlled storage conditions help minimize exposure to moisture, contamination and other environmental factors that could affect API quality.
Typical documentation for Protriptyline Hydrochloride API may include:
Protriptyline Hydrochloride is an established pharmaceutical API with a defined USP monograph and well-characterized chemical identity. The current USP-based specification provides numerical controls for assay, residue on ignition, pH and loss on drying, supporting consistent quality evaluation.
Its defined molecular structure, established pharmaceutical use and recognized analytical requirements make Protriptyline Hydrochloride suitable for pharmaceutical formulation and API manufacturing applications.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 99.0–101.0% |
| Loss on Drying | NMT 0.3% |
| Residue on Ignition | NMT 0.1% |
| pH (1% Solution) | 5.0–6.5 |