Pharmacokinetics of Moxidectin in the Southern Hairy-Nosed Wombat (Lasiorhinus Latifrons)

Abstract

Sarcoptic mange, caused by Sarcoptes scabiei var. wombati, could be a significant threat to populations of southern hairy-nosed wombats (Lasiorhinus latifrons; SHNW) in Australia. Treatment is currently based on the off-label use of various parasiticidal drugs, with limited clinical efficacy trials. Our primary aim was to determine the pharmacokinetic parameters of a macrocyclic lactone, moxidectin, to assist in the development of effective treatment protocols. Pharmacokinetic parameters were determined in four female SHNW following a single subcutaneous injection of 0.2 mg/kg moxidectin. Blood samples were collected for 38 days following injection (August-September 2008), for analysis using liquid chromatography and tandem mass spectrometry. The mean peak plasma concentration occurred at 13.6 hr, with a mean peak plasma level of 98.6 ng/ml. The mean elimination half-life was 5.03 days, resulting in a mean area under the curve of 377 ng.day/ml. The peak plasma moxidectin concentration was higher than that seen in livestock species but the plasma elimination half-life was shorter. This study suggests that a single injection of 0.2 mg/kg moxidectin may not be sufficient to clear a mange infection in this species.

Population‐scale treatment informs solutions for control of environmentally transmitted wildlife disease

“…We suspect this is primarily due to the delivery method (burrow flap), which administers a single dose indiscriminately and anecdotally can be avoided or disrupted by wombats. It is also difficult to quantify the treatment dose that is delivered, but a dose of less than 2 ml may be insufficient to clear infection or confer complete protection to the host (Death et al, 2011 One potential caveat of this research is the possibility that healthy wombats were underrepresented during dusk surveys. In Tasmania, healthy bare-nosed wombats exhibit both diurnal and nocturnal activity, with a trend for increased observations of healthy wombats at night, although this varies with location (DPIPWE, 2017a).…”

“…We suspect this is primarily due to the delivery method (burrow flap), which administers a single dose indiscriminately and anecdotally can be avoided or disrupted by wombats. It is also difficult to quantify the treatment dose that is delivered, but a dose of less than 2 ml may be insufficient to clear infection or confer complete protection to the host (Death et al, ). Improvements in delivery success appear to be the single most important factor in control of S. scabiei .…”

The Efficacy of Anthelmintic Drugs Against Nematodes Infecting Free-Ranging Eastern Grey Kangaroos, Macropus Giganteus

“…Wombats had a higher peak plasma concentration but a shorter plasma elimination halflife than did livestock species, suggesting that moxidectin elimination is less influenced by the lower metabolic rates of marsupials than it is by the amount of body fat (Death et al, 2011). For lipophilic macrocyclic lactones such as moxidectin and ivermectin, subcutaneous fat is likely to influence drug absorption (Oksanen et al, 1995), and these drugs are preferentially distributed into adipose tissue which may act as a drug reservoir and facilitate persistence (Zulalian et al, 1994).…”

“…The only study of the pharmacokinetics of moxidectin in a marsupial was on the southern hairy-nosed wombat, (Lasiorhinus latifrons; Death et al, 2011). Wombats had a higher peak plasma concentration but a shorter plasma elimination halflife than did livestock species, suggesting that moxidectin elimination is less influenced by the lower metabolic rates of marsupials than it is by the amount of body fat (Death et al, 2011).…”

Effects and Treatment of Sarcoptic Mange in Southern Hairy-Nosed Wombats (Lasiorhinus Latifrons)

“…In captive common wombats, Skerratt et al (2004) found that one injection (0.4 mg/kg) cleared mild mange but that retreatment was required for the mostseverely diseased animals. A pharmacokinetics study of another macrocyclic lactone, moxidectin, suggested that a single injection at 0.2 mg/kg would not clear mange in SHNW (Death et al, 2011). To further our understanding, our aims were to establish the clinical and cellular effects of mange in SHNW and determine the effectiveness of a single dose of ivermectin for treating infected wild and captive animals.…”