Binding characteristics of ivermectin in plasma from collie dogs

Two types of experiments were performed in an effort to demonstrate a role for plasma proteins in determining the amount of ivermectin available for transport across the blood-brain barrier of collie dogs sensitive to the effects of the compound. The solubility of ivermectin in plasma from non-sensitive and sensitive collies was measured and found to be identical at 100 micrograms/ml. An assay for measuring the low affinity binding interaction of ivermectin with plasma components was developed. The amount of ivermectin bound per unit of plasma was the same for samples from sensitive and non-sensitive dogs. Dog serum albumin and the high density lipoprotein portion of the plasma were both capable of binding ivermectin. No differences in the binding characteristics of ivermectin in plasma from ivermectin sensitive and non-sensitive collies were found.