Percutaneous malathion absorption in the harvested perfused anuran pelvic limb

Amphibians at risk? Susceptibility of terrestrial amphibian life stages to pesticides

“…For example, in the case described above, ethanol was used as the application vehicle together with malathion, whereas in field applications a variety of vehicle solvent combinations may be used, influencing the absorption kinetics. Therefore, the risk arising from true environmental exposure may be higher than in the reported experiments because malathion is more likely to partition to the skin from an aqueous or oily formulation 23.…”

“…Willens et al examined the percutaneous absorption of the insecticide malathion by anuran skin in vitro 22, 23. In the diffusion cell model, the total absorption (percentage of rate administered, 26 µg/cm 2 ) of ventral and dorsal skin of the American bullfrog (Rana catesbeiana) was 81 and 69% and for the cane toad ( Bufo marinus ) 83 and 77% 22.…”

“…In the diffusion cell model, the total absorption (percentage of rate administered, 26 µg/cm 2 ) of ventral and dorsal skin of the American bullfrog (Rana catesbeiana) was 81 and 69% and for the cane toad ( Bufo marinus ) 83 and 77% 22. In contrast, with the harvested perfused anuran pelvic limb (HPAPL) model, 46% absorption of the total malathion dose administered was measured in frog skin (pelvic limb) 23. The HPAPL model maintains the anatomic and physiologic integrity of the skin of the pelvic limb, so it permits a more accurate physiological representation of in vivo cutaneous pharmacokinetics than diffusion cell models.…”

Measurements of Common Iliac Arterial Blood Flow in Anurans Using Doppler Ultrasound

“…1,3,9,14,15,19,20 To characterize cutaneous absorption of xenobiotics, in vitro models, such as the two-compartment Teflon flow-through diffusion cell, allow careful control of key environmental variables including temperature, humidity, and pH. 22 They can also minimize use of live animals in experiments. Diffusion cells provide a morphologically complete and intact skin barrier and eliminates confounding factors in the analysis of in vivo cutaneous absorption, including absorption, metabolism, or elimination by other routes.…”

“…Though diffusion cell assays are simple to perform using anuran (frogs and toads) skin, they cannot account for potential effects of variation in blood flow on xenobiotic transport. 22 Knowledge of the range of arterial flow dynamics in anurans is important for the development of appropriate experimental systems to study cutaneous absorption of vasoactive compounds. Diagnostic ultrasound is a well-established imaging modality in mammalian medicine, but its application in amphibians has been relatively limited.…”