Effect of preservatives and conditions of storage on the potency of allergy extracts.

The effect of several preservatives and conditions of storage on the potency of allergy extracts in dilutions of 1:100 to 1:10,000 was measured by radioallergosorbent test (RAST) inhibition. Accelerated loss of extract potency occurred with intermittent exposure to room temperature. Additional extracts helped maintain the potency of the others in a mixture, especially at greater dilutions. No increased loss of potency could be demonstrated with partial filling of vials. Of paramount importance in the maintenance of extract potency was the preservative employed. There was marked loss of potency in phenol saline, no demonstrable loss in 50% glycerine, and intermediate loss with 10% glycerin or 0.03% human serum albumin (HSA). The preservative effects of 10% glycerin and 0.03% HSA were additive.