Scopolamine Butylbromide, commonly known internationally as Hyoscine Butylbromide or N-Butylscopolammonium Bromide, is a quaternary ammonium anticholinergic and antispasmodic active pharmaceutical ingredient. It is widely used in pharmaceutical formulations intended to relieve smooth-muscle spasms, particularly spasms associated with the gastrointestinal, biliary and urinary tracts. The substance is also commonly recognized under the brand name Buscopan.
Scopolamine Butylbromide API is a small-molecule pharmaceutical substance supplied as the bromide salt of N-butylscopolamine. The API has the molecular formula C₂₁H₃₀BrNO₄ and a molecular weight of approximately 440.4 g/mol. Its primary CAS number is 149-64-4, which is also listed by the FDA Global Substance Registration System and other chemical databases.
The substance is structurally related to scopolamine but differs significantly in pharmaceutical properties because the N-butyl substitution produces a permanently charged quaternary ammonium compound. This contributes to its peripheral anticholinergic activity and limited penetration into the central nervous system compared with tertiary amine anticholinergics.
Scopolamine Butylbromide is a quaternary ammonium compound and an organic bromide salt. It acts primarily as a muscarinic receptor antagonist, reducing the action of acetylcholine at parasympathetic nerve endings and smooth-muscle cells. This produces relaxation of spasmodic smooth muscle.
The API is described pharmacopoeially as a white or almost white crystalline powder. It is freely soluble in water, while solubility in alcohol is substantially lower. The Brazilian Pharmacopoeia specifies a melting range of 139–141°C and specific optical rotation of −18 to −20°, determined on the desiccated substance in a 10% w/v aqueous solution.
Scopolamine Butylbromide is primarily used as an antispasmodic for the symptomatic treatment of painful smooth-muscle spasms. Its pharmaceutical applications include gastrointestinal cramping and spasms and, depending on the approved formulation and market, spasms involving the biliary and urinary tracts. PubChem describes its use in abdominal cramping and pain associated with gastrointestinal spasms.
The API is used in both oral and parenteral pharmaceutical products. Pharmacopoeial preparations include Hyoscine Butylbromide Tablets and Hyoscine Butylbromide Injection.
Scopolamine Butylbromide acts by competitively blocking muscarinic acetylcholine receptors. By inhibiting parasympathetic cholinergic signaling in smooth muscle, it reduces involuntary muscle contractions and produces an antispasmodic effect. Its quaternary ammonium structure contributes to its predominantly peripheral activity.
Pharmacopoeial quality control of Scopolamine Butylbromide includes identification, assay, related substances, loss on drying, sulfated ash and stereochemical/optical-rotation testing.
The Brazilian Pharmacopoeia specifies 98.0–101.0% content calculated on the desiccated substance. The published Ph. Eur./BP monograph information likewise specifies 98.0–101.0% on the dried substance. The BP/Ph. Eur. monograph also specifies loss on drying NMT 2.5% and sulfated ash NMT 0.1%.
The BP reference-standard catalogue currently lists Hyoscine Butylbromide under CAS 149-64-4 and identifies it as a quantitative reference standard.
Manufacturing of Scopolamine Butylbromide API requires controlled chemical synthesis, purification, drying and analytical release testing. Because the substance contains defined stereochemistry, appropriate stereochemical control is important during synthesis and quality assessment.
A pharmaceutical-grade manufacturing process should control starting materials, reaction conditions, purification efficiency, residual solvents, related substances, water/moisture and inorganic residues. Validated chromatographic and spectroscopic methods should be used for identification, assay and impurity profiling.
Scopolamine Butylbromide is a white or almost white crystalline powder with a molecular weight of approximately 440.4 g/mol. It is freely soluble in water. Pharmacopoeial data report a melting range of 139–141°C and specific optical rotation of −18 to −20° under the specified test conditions.
Scopolamine Butylbromide API should be packed in suitable pharmaceutical-grade, well-closed containers that protect the material from contamination and environmental exposure. Storage should follow the applicable pharmacopoeial requirements, validated stability data and the manufacturer's approved API specification.
Typical pharmaceutical documentation may include:
A qualified Scopolamine Butylbromide API manufacturer should maintain controlled manufacturing processes, validated analytical methods and appropriate pharmaceutical quality systems. Consistent control of assay, related substances, moisture, sulfated ash and stereochemical characteristics is important for producing reliable Hyoscine Butylbromide API for pharmaceutical formulation.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 2.5% |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.4% |
| Melting Point | 139–141°C |