Pharmacokinetics of moxidectin following topical administration to New Zealand rabbits

Efficacy of a spot-on combination of fluralaner plus moxidectin against naturally acquired Sarcoptes scabiei infestation in 10 pet rabbits: Retrospective case series

BACKGROUND

Current treatments for sarcoptic mange in rabbits mainly include administration of avermectines every 10-30 days. Recently, a single oral dose of fluralaner has been shown to be effective to treat sarcoptic mange in 12 pet rabbits over a three-month period.

OBJECTIVES

To retrospectively assess the efficacy of a spot-on combination of fluralaner plus moxidectin (Bravecto Plus) for the treatment of sarcoptic mange in rabbits.

ANIMALS

Ten client-owned rabbits diagnosed with sarcoptic mange.

MATERIALS AND METHODS

An application of fluralaner plus moxidectin at an average dose of 25 mg/kg and 1.24 mg/kg, respectively, was administered topically once. Parasitological and dermatological examination was carried out weekly for one month and monthly for three months.

RESULTS

The median age at diagnosis was 15 (range 3-48) months. Based on the age of onset, there were three juvenile (<6-month-old) and seven adult-onset cases. Of those, four were generalized (head, feet and/or genital area) and six were localized form (head only). The combination of fluralaner plus moxidectin resulted in 100% eradication of mites and complete resolution of all skin lesions within 21 days. Recurrence was not observed 90 days post-treatment. Relapse was not observed in one case followed up for a further four months and two rabbits followed up for a further six months. The other pets were lost to follow-up.

CONCLUSIONS AND CLINICAL RELEVANCE

These results indicated that a single dose of a formulation containing fluralaner plus moxidectin, at 25 mg/kg and 1.24 mg/kg, respectively, was effective for the treatment of naturally occurring sarcoptic mange in rabbits.

The pharmacokinetics of moxidectin following intravenous and topical administration to swine

The pharmacokinetic parameters of moxidectin (MXD) after intravenous and pour-on (topical) administration were studied in sixteen pigs at a single dose of 1.25 and 2.5 mg/kg BW (body weight), respectively. Blood samples were collected at pretreatment time (0 hr) over 40 days. The plasma kinetics were analyzed by WinNonlin 6.3 software through a noncompartmental model. For intravenous administration (n = 8), the elimination half-life (λ_Z ), the apparent volume of distribution (V_z ), and clearance (Cl) were 10.29 ± 1.90 days, 89.575 ± 29.856 L/kg, and 5.699 ± 2.374 L/kg, respectively. For pour-on administration (n = 8), the maximum plasma drug concentration (C_max ), time to maximum plasma concentration (T_max ), and λ_Z were 7.49 ng/ml, 1.72, and 6.20 days, respectively. MXD had a considerably low absolute pour-on bioavailability of 9.2%, but the mean residence time (MRT) for pour-on administration 10.88 ± 1.75 days was longer than 8.99 ± 2.48 days for intravenous administration. These results showed that MXD was absorbed via skin rapidly and eliminated slowly. The obtained data might contribute to refine the dosage regime for topical MXD administration.