Orciprenaline API, also known as Metaproterenol, is a synthetic sympathomimetic compound belonging to the phenylethanolamine class. It is recognized pharmacologically as a selective β2-adrenergic receptor agonist and has been used as a bronchodilator for the management of bronchospasm and respiratory conditions such as asthma. PubChem identifies Orciprenaline/Metaproterenol under CAS 586-06-1, with molecular formula C11H17NO3 and molecular weight 211.26 g/mol.
For pharmaceutical manufacturing, Orciprenaline is commonly encountered in its sulfate salt form, Orciprenaline Sulfate, which has the CAS number 5874-97-5 and molecular weight 520.6 g/mol. The Japanese Pharmacopoeia (JP XVII) provides an official monograph for Orciprenaline Sulfate and specifies a minimum content of 98.5%, calculated on the dried basis.
Orciprenaline acts primarily through stimulation of β-adrenergic receptors, with β2 activity contributing to relaxation of bronchial smooth muscle. This pharmacological profile has made metaproterenol/orciprenaline an established bronchodilator compound. PubChem classifies metaproterenol as a β2-adrenergic agonist and identifies its therapeutic association with asthma and bronchial spasm.
The API is therefore relevant to pharmaceutical formulations and research programs involving bronchodilator and adrenergic respiratory medicines. Depending on the intended manufacturing process and dosage form, the active ingredient may be handled as the free base or, more commonly for pharmaceutical applications, as the sulfate salt.
Orciprenaline Sulfate is particularly important from a pharmaceutical API perspective because it has an established pharmacopoeial monograph. The Japanese Pharmacopoeia identifies Orciprenaline Sulfate as a hemisulfate with the chemical formula (C11H17NO3)2·H2SO4 and molecular weight 520.59. The official monograph describes it as white crystals or crystalline powder.
The JP XVII monograph states that Orciprenaline Sulfate contains not less than 98.5% of the specified compound on the dried basis. It also specifies a pH range of 4.0–5.5 for a solution prepared by dissolving 1.0 g in 10 mL of water.
Orciprenaline free base has the molecular formula C11H17NO3 and molecular weight 211.26 g/mol. PubChem reports an exact mass of 211.12084340 Da, XLogP3 of 0.7, hydrogen-bond donor count of 4, hydrogen-bond acceptor count of 4, rotatable bond count of 4, and topological polar surface area of 72.7 Ų.
For the sulfate form, PubChem reports molecular formula C22H36N2O10S, molecular weight 520.6 g/mol, exact mass 520.20906652 Da, and topological polar surface area 228 Ų.
The JP XVII monograph provides several quantitative quality requirements for Orciprenaline Sulfate. These include a minimum assay/content of 98.5%, heavy metals at a maximum of 10 ppm, Orciprenalone absorbance at 328 nm not exceeding 0.075, loss on drying not exceeding 1.5%, and residue on ignition not exceeding 0.1%.
The same monograph specifies a melting point of approximately 220°C with decomposition and a pH range of 4.0–5.5 for the prescribed aqueous solution. It also specifies an assay titration using 0.1 mol/L perchloric acid, with each 1 mL equivalent to 52.06 mg of Orciprenaline Sulfate.
For commercial pharmaceutical applications, Orciprenaline API should be supported by appropriate analytical documentation such as a Certificate of Analysis, specification sheet, safety documentation, batch information and applicable quality-control records. Where Orciprenaline Sulfate is supplied against a pharmacopoeial specification, the relevant monograph requirements should be used as the quality reference.
The distinction between Orciprenaline free base (CAS 586-06-1) and Orciprenaline Sulfate (CAS 5874-97-5) is particularly important when preparing procurement documentation, regulatory records, specifications, analytical methods and formulation documentation. PubChem independently identifies the sulfate salt as Orciprenaline Sulfate/Metaproterenol Sulfate and confirms its CAS number and molecular formula.
| 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 0.1% |
| pH (1% Solution) | 4.0–5.5 |
| Individual Impurity | NMT 0.1% |
| Total Impurities | ≤ 1.5% |
| Water Content | NMT 1.0% |
| Melting Point | ≈220°C, decomposition |