Hyoscyamine
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
1 DEFINITION
Hyoscyamine contains NLT 98.0% and NMT 101.0% of hyoscyamine (C₁₇H₂₃NO₃), calculated on the dried basis.
[Caution—Handle Hyoscyamine with exceptional care since it is highly potent.]
2 IDENTIFICATION
A.
Standard solution: Transfer 36 mg of USP Hyoscyamine Sulfate RS to a 60-mL separator with the aid of 5 mL of water. Add 1.5 mL of 1 N sodium hydroxide and 10 mL of chloroform to the separator. Shake for 1 min, allow the layers to separate, and pass the chloroform extracts through a filter of about 2 g of anhydrous granular sodium sulfate supported on a pledget of glass wool. Extract the aqueous layer with two additional 10-mL portions of chloroform, filtering and combining with the main extract. Evaporate the chloroform solution under reduced pressure to dryness, and dissolve the residue in 10 mL of carbon disulfide.
Sample solution: Prepare as directed in the Standard solution using 30 mg of Hyoscyamine.
Acceptance criteria: The IR absorption spectrum (determined in a 1-mm cell) of the Sample solution exhibits maxima only at the same wavelengths as those of the Standard solution.
B.
Sample: 60 mg
Analysis: Dissolve the Sample in 1 mL of 0.2 N hydrochloric acid, and add gold chloride TS, dropwise with shaking, until a definite precipitate separates. Add a small amount of 3 N hydrochloric acid, dissolve the precipitate with the aid of heat, and then allow to cool.
Acceptance criteria: Lustrous golden yellow scales are formed (distinction from atropine and Scopolamine).
3 ASSAY
Procedure
Sample: 500 mg
Analysis: Dissolve the Sample in 50 mL of glacial acetic acid, and add 1 drop of crystal violet TS. Titrate with 0.1 N perchloric acid VS to a green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 28.94 mg of hyoscyamine (C₁₇H₂₃NO₃).
Acceptance criteria: 98.0%–101.0% on the dried basis
4 IMPURITIES
Residue on Ignition 〈281〉: NMT 0.1%
Limit of Foreign Alkaloids and Other Impurities
Standard solution: 24 mg/mL of USP Hyoscyamine Sulfate RS in methanol
Sample solution A: 20 mg/mL of Hyoscyamine in methanol
Sample solution B: 1 mg/mL of Hyoscyamine from Sample solution A in methanol
Chromatographic system
(See Chromatography 〈621〉, Thin-Layer Chromatography.)
Adsorbent: 0.5-mm layer of chromatographic silica gel
Developing solvent system: Chloroform, acetone, and diethylamine (5:4:1)
Spray reagent: Potassium iodoplatinate TS
Analysis: Apply 25 µL of Sample solution A, 1 µL of Sample solution B, and 5 µL of the Standard solution to a suitable thin-layer chromatographic plate. Allow the spots to dry, and develop the chromatogram in the Developing solvent system until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by spraying with the Spray reagent.
Acceptance criteria: The Rf value of the principal spot of each Sample solution corresponds to that of the Standard solution. No secondary spot of Sample solution A exhibits intensity equal to or greater than the principal spot of Sample solution B (0.2%).
5 SPECIFIC TESTS
Melting Range or Temperature 〈741〉: 106°–109°
Optical Rotation, Specific Rotation 〈781S〉
Sample solution: 10 mg/mL, in dilute alcohol (1 in 2)
Acceptance criteria: –20° to –23°
Loss on Drying 〈731〉
Analysis: Dry under vacuum over silica gel to constant weight.
Acceptance criteria: NMT 0.2%
6 ADDITIONAL REQUIREMENTS
Packaging and Storage: Preserve in tight, light-resistant containers.
USP Reference Standards 〈11〉
USP Hyoscyamine Sulfate RS
