The moxidectin component of advantage multi topical, supposedly is rapidly absorbed through the skin within 30 minutes into the subcutaneous fat layer. The flea component supposedly stays within the dermal cells and takes much longer to spread through the dermal tissues, the way I understand. They should have left the flea insecticide completely out of it. As it is, it’s another thing to be concerned about, and that I really know little about.
Evidently the moxidectin component is highly lipophilic, meaning 1. showing a marked attraction to, or solubility in, lipids.
2. having an affinity for oil or fat.
“Actual preventive products may perform differently.
Table 2 summarizes important differences in heartworm
preventives. Properties such as unique pharmacologic
behavior could result in improved efficacy. For example,
moxidectin is a highly lipophilic molecule, resulting in
higher drug concentrations and delayed elimination from
the host. Moxidectin in the Advantage MultiĀ® for Dogs
topical formulation achieved high concentrations in plasma
(15.1 Āµg/L) and maintained levels at or above about 12 Āµg/L
for the 30-day treatment period. More importantly, consistent
administration of moxidectin (Advantage MultiĀ® for Dogs) to
dogs for 4 or more months resulted in a continuous presence
(steady-state; approximately 36 Āµg/L) of moxidectin in
plasma.8 Product properties such as these may prove to be
important for effective heartworm prevention.”
See pages 8-11. See also the tables and chart. Note; this comes from Bayer Pharma’s own website, and by the Dr. Byron Blackburn, who I think has financial bias.. Regardless of any bias, I think the article still has some good information.
http://www.bayerdvm.com/show.aspx/canine-heartworm-disease-blagburn
