Effects of summer mailing on in vivo and in vitro relative potencies of standardized timothy grass extract.

BACKGROUND Allergen extracts can degrade when exposed to temperatures significantly beyond the optimum storage recommendation of 4 degrees C. Many allergen extracts are mailed to their final destinations throughout the year with exposure to varied environmental conditions. OBJECTIVE To evaluate the effect of summer mailing on the in vitro and in vivo potency of timothy grass extract. METHODS Standardized timothy grass extracts, 10,000 and 100,000 BAU/mL, were mailed round-trip between San Antonio, Texas, and Phoenix, Arizona, during August 2007. In-transit temperatures were recorded using a portable temperature logger. After mailing of the extracts, we performed quantitative in vitro enzyme-linked immunosorbent assay inhibition and in vivo ID50 EAL (Intradermal Dilution for 50-mm Sum of Erythema Determines Bioequivalent Allergy Units) analysis. RESULTS Measured extract exposure temperatures were greater than 20 degrees C for 11 days and 30 degrees C for 6 hours during standard mailing in weather temperatures exceeding 38 degrees C. Enzyme-linked immunosorbent assay inhibition results for the 100,000- and 10,000-BAU/mL control samples were 97,900 and 10,580 BAU/mL, respectively, and for the mailed extracts were 96,800 and 7830 BAU/mL, respectively. These measurements fell within the current Food and Drug Administration lot release limits (67%-149%) and stability limits (50%-200%) relative to the standardized reference. The ID50EAL determinations of the control vs mailed extracts were 12.98 vs. 12.28, 12.66 vs. 12.32, and 11.97 vs 11.70 for the 3 patients. These differences were not statistically significant. CONCLUSIONS Mailing of timothy grass extract produced no significant reductions in in vitro relative potencies or in vivo skin test reactivity in 3 sensitive patients.