Procaterol is a selective, long-acting β2-adrenergic receptor agonist used as a bronchodilator. It promotes relaxation of airway smooth muscle and has been used in the management of bronchospasm associated with respiratory disorders including asthma and chronic obstructive pulmonary disease.
The pharmaceutical substance is commonly supplied as Procaterol Hydrochloride Hydrate (hemihydrate). The Japanese Pharmacopoeia identifies the substance as Procaterol Hydrochloride Hydrate, with the chemical formula C16H22N2O3·HCl·½H2O and molecular weight 335.83 g/mol.
Procaterol is a quinolinone-derived β2-adrenergic agonist. The free base has CAS 72332-33-3, molecular formula C16H22N2O3, and molecular weight 290.36 g/mol.
For pharmaceutical API applications, the hydrochloride hydrate/hemihydrate form is particularly important. FDA GSRS identifies Procaterol Hydrochloride Hemihydrate under UNII 8404I5HKFJ and CAS 81262-93-3. The corresponding JP monograph lists the anhydrous reference CAS as 62929-91-3.
| Parameter | Details |
|---|---|
| Product Name | Procaterol |
| Pharmaceutical Form | Procaterol Hydrochloride Hydrate / Hemihydrate |
| CAS Number | 81262-93-3 |
| Related Anhydrous CAS | 62929-91-3 |
| Free Base CAS | 72332-33-3 |
| Molecular Formula | C16H22N2O3·HCl·½H2O |
| Molecular Weight | 335.83 g/mol |
| Free Base Molecular Weight | 290.36 g/mol |
| Procaterol HCl MW | 326.82 g/mol |
| FDA UNII | 8404I5HKFJ |
| Pharmacological Class | Selective β2-adrenergic receptor agonist |
| Therapeutic Class | Bronchodilator |
| Appearance | White to pale yellow-white crystals or crystalline powder |
| pH | 4.0–5.0 |
| Melting Point | About 195°C, with decomposition |
| Optical Rotation | No optical rotation under JP test conditions |
| Water Solubility | Soluble |
| Methanol Solubility | Soluble |
| Ethanol Solubility | Slightly soluble |
| Diethyl Ether | Practically insoluble |
The JP XVIII monograph confirms the hydrate formula, appearance, solubility, pH and thermal behavior.
Procaterol acts primarily through stimulation of β2-adrenergic receptors in bronchial smooth muscle. This produces bronchodilation and can help improve airway airflow.
It has been used in respiratory medicines for conditions involving bronchoconstriction, including asthma and COPD. Procaterol is available in oral and inhaled dosage forms in markets where it is approved.
Procaterol hydrochloride hydrate is therefore relevant to pharmaceutical manufacturing of respiratory products, analytical reference standards, formulation development and quality-control testing.
The JP XVIII Procaterol Hydrochloride Hydrate monograph provides the strongest publicly verified numerical specifications identified during research.
| Detailed Specification | Correct Value |
|---|---|
| Identification | Complies — UV / IR / chloride identification |
| Assay | NLT 98.5% of Procaterol Hydrochloride, calculated on anhydrous basis |
| LOD | N/A — JP controls water separately |
| Residue on Ignition | NMT 0.1% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 4.0–5.0 |
| Individual Impurity | N/A as a separate numerical limit — JP uses a total related-substances comparison |
| Total Impurities / Related Substances | NMT 1.0% equivalent by the JP reference-solution procedure |
| Water Content | 2.5–3.3% |
| Specific Rotation | No optical rotation under JP test conditions |
| Melting Point | About 195°C, with decomposition |
| Solubility | Soluble in water, formic acid and methanol; slightly soluble in ethanol; practically insoluble in diethyl ether |
| Appearance | White to pale yellow-white crystals or crystalline powder |
| Storage | Well-closed, light-resistant containers |
The JP related-substances test establishes that the total area of peaks other than procaterol must not exceed the procaterol peak area in the reference solution, corresponding to the approximately 1% comparison level used in the monograph procedure. The monograph also specifies 2.5–3.3% water and NMT 0.1% residue on ignition.
For comparison, a current FUJIFILM Wako analytical product lists Procaterol Hydrochloride Hemihydrate at 98.0% minimum by HPLC, with white-to-pale-yellow crystalline/powder appearance and melting around 195°C with decomposition.
Procaterol API manufacturing requires control of the hydrochloride hydrate form, assay, water content, related substances, inorganic residue and elemental impurities. The hydrate state is particularly important because the JP specification explicitly controls water at 2.5–3.3%.
Analytical characterization can include UV-visible spectroscopy, FTIR, HPLC/LC methods, chloride identification, water determination and residue-on-ignition testing. The JP monograph specifically uses chromatographic testing for related substances and requires chromatographic separation of procaterol from threoprocaterol with a resolution of at least 3.
Procaterol Hydrochloride Hydrate should be packaged in well-closed, light-resistant containers. The JP monograph notes that the material gradually becomes colored when exposed to light and specifically requires light-resistant storage.
For controlled pharmaceutical storage, temperature and humidity should be maintained according to the validated stability program for the particular API batch and packaging configuration.
Typical documentation for Procaterol API may include:
Procaterol requires careful control of its hydrochloride hemihydrate form, particularly because the official JP monograph specifies assay on an anhydrous basis while separately controlling water content at 2.5–3.3%. A properly controlled manufacturing and analytical program should therefore verify identity, assay, hydrate/water state, related substances, heavy metals and residue on ignition.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | NLT 98.5% anhydrous basis |
| pH (1% Solution) | 4.0–5.0 |
| Water Content | 2.5–3.3% |
| Melting Point | About 195°C (decomp.) |