High-pressure liquid chromatographic assay of theophylline in dog feces following oral administration of sustained-release products.
A solid-phase-extraction reversed-phase HPLC assay is described for the determination of theophylline embedded in dog feces as powder, sustained-release tablets, or capsules. The feces is extracted with 5% isopropyl alcohol in chloroform in the presence of beta-hydroxypropyl-theophylline as the internal standard. Separation and quantitation are achieved with a C18 analytical column. UV absorbance is monitored at 280 nm. Recovery of theophylline was > 50%. The assay is linear between 10 and 400 mg amounts of theophylline in 50 g of feces. Inter- and intraday coefficients of variation of the chromatographic assay were < 3%, and the extraction procedure was highly reproducible with coefficients of variation of < 10% at amounts of drug from 10 to 400 mg. By keeping the stool/solvent extraction ratio constant, the method is equally effective in extracting theophylline from different sizes of stool samples (50 versus 200 g of stool). The assay was applied to evaluate the theophylline content in feces following oral administration of the drug to dogs as tablet (Theo-Dur) and capsule (Slo-Bid) dosage forms. The resulting fecal recovery values of each product were inversely related to the corresponding bioavailability values obtained from the literature.
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Department of Pharmaceutics, School of Pharmacy, State University of New York at Buffalo 14260.
Meek
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Jusko
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WJ
D000818:Animals; D001682:Biological Availability; D002214:Capsules; D002851:Chromatography, High Pressure Liquid; D003692:Delayed-Action Preparations; D004285:Dogs; D005243:Feces / Q000737:chemistry*; D013607:Tablets; D013806:Theophylline / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics
D002214:Capsules; D003692:Delayed-Action Preparations; D013607:Tablets; D013806:Theophylline