Hydroxyzine Pamoate is an antihistamine and anxiolytic active pharmaceutical ingredient belonging to the piperazine derivative class. It is the pamoate salt of hydroxyzine and produces antihistaminic, anticholinergic and central nervous system depressant effects.
Hydroxyzine Pamoate has the molecular formula C44H50Cl2N4O8 and a molecular weight of 763.88 g/mol. Its CAS Number is 2192-20-3.
Hydroxyzine Pamoate is a salt form of hydroxyzine prepared with pamoic acid. The pamoate form provides a stable pharmaceutical form of hydroxyzine for oral formulations.
Hydroxyzine is used primarily for the symptomatic management of anxiety, relief of pruritus associated with allergic conditions and as a sedating antihistamine.
Hydroxyzine acts primarily as an H1 histamine receptor antagonist. By blocking histamine-mediated signaling, it reduces histamine-related symptoms such as itching and allergic manifestations.
Hydroxyzine also has anticholinergic and central nervous system depressant activity, contributing to its sedative effects.
Hydroxyzine Pamoate API is used in the development and manufacture of:
Hydroxyzine Pamoate is manufactured through controlled chemical synthesis followed by salt formation, purification, drying and pharmaceutical quality testing.
Quality control may include identification, assay, related substances, water content, residue on ignition, pH and residual solvents according to the applicable approved specification.
Hydroxyzine Pamoate is generally supplied as a white or almost white crystalline powder. It is practically insoluble in water, consistent with the characteristics of the pamoate salt.
Hydroxyzine Pamoate should be stored in a tightly closed container, protected from excessive moisture, heat and direct light. Storage conditions should follow the manufacturer's current CoA, SDS and validated stability requirements.
Depending on the intended pharmaceutical application, documentation may include:
Hydroxyzine Pamoate is an established antihistamine and anxiolytic pharmaceutical ingredient. Its H1-antagonist activity and additional anticholinergic and sedative properties make it relevant to antihistamine, antipruritic and anxiolytic pharmaceutical formulations.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 2.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 20 ppm |
| pH (1% Solution) | 4.0 – 7.0 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 2.0% |
| Water Content | NMT 2.0% |
| Melting Point | Approximately 180–185°C (decomposition) |