Cyclodextrins (CDs) are a family of cyclic oligosaccharides produced by enzymatic degradation of starch. The characteristic feature of these molecules is their ring-shaped 3D conical structure, with a hydrophilic outer surface and lipophilic cavity in the center capable of receiving a lipophilic “guest” molecule. In the pharmaceutical industry, CDs have been used as complexing agents to increase the water solubility of poorly soluble drugs, and to increase their bioavailability and stability. Betadex is a 6-membered ring CD molecule. Betadex sulfobutyl ether sodium is a β-cyclodextrin derivative with a sodium sulfonate salt separated from the lipophilic cavity by a sulfobutyl ether spacer group. It can act as a soluble carrier for drugs that have poor water solubility by forming inclusion complexes.<br/>The presence of oxidizable hydroxyl groups on CDs makes them well suited for determination by high-performance anion-exchange (HPAE) chromatography in combination with pulsed amperometric detection (PAD). The USP-NF Betadex Sulfobutyl Ether Sodium monograph describes a HPAE-PAD method for the determination of betadex impurity in betadex sulfobutyl ether sodium. Here, we evaluated the USP monograph method and evaluated some changes. Betadex was separated on a Thermo Scientific™ Dionex™ IonPac™ AS11 column followed by PAD detection using the specified 3-potential waveform with a gold conventional working electrode. Two commercial betadex sulfobutyl ether sodium samples were tested and found to contain betadex impurity under the specified limit prescribed in the USP monograph. We also demonstrated that this method could be executed with 4-potential waveforms and a disposable working electrode with comparable results. These changes will improve the method long term-reproducibility and ruggedness. The separation, linearity, reproducibility, and sensitivity were found to meet or exceed the current USP Betadex Sulfobutyl Ether Sodium monograph performance requirements.

Determination of betadex (β-cyclodextrin) according to the USP betadex sulfobutyl ether sodium monograph

2019 Fall National Meeting

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