Identification of gliadin presence in pharmaceutical products

Celiac disease is characterized by hypersensitivity to the alcohol-soluble wheat proteins called gliadins. Total avoidance of gliadin is the lifelong treatment for such patients. However, wheat gliadins are often present as impurities in industrial starch commonly used in the preparation of different pharmaceutical products. Therefore, some drugs might contain gliadin, which can be dangerous for sensitive patients if taken in large amounts or used permanently. The purpose of this study was to develop a sensitive, reliable assay that is specific for the detection of gliadins in pharmaceutical products. Gliadins were extracted here using sodium dodecyl sulfate rather than 70% ethyl alcohol, which has been the traditional solvent. This gliadin extract was utilized in a dot-blot assay that incorporated an antigliadin antibody developed in rabbit and labeled with peroxidase. 4-Chloro-1-naphthol was used as a peroxidase-specific substrate. Isolated wheat gliadin was used as the positive control. Dilution experiments showed that the lower level of sensitivity for the assay was in the range of 0.0045 mg/ml of gliadin, which is a concentration level lower than that suggested for a gluten-free diet. The assay developed here revealed that 71.2% of 59 prescription and nonprescription drugs tested contained gliadin in the amount detected by our dot-blot assay. The prescription drugs tested were among the top 50 most frequently dispensed in U.S. community pharmacies. The nonprescription drugs were among those that constitute the largest sales in the United States. The results showed that the simple dot-blot assay developed here can be used for pharmaceutical testing performed either by hospital laboratories or by patients themselves.