title: Skin distribution of imidacloprid by microautoradiography after topical administration to beagle dogs.
abstract: To investigate the cutaneous distribution, localization, and persistence of imidacloprid in dogs, Advantage Topical Solution labeled with carbon 14 ((14)C) was topically applied as a single treatment at label rates and application pattern based on body weight to two adult beagles. One dog (8.5 kg) received 1.0 mL of the test solution at a single spot in the interscapular area (14 mg active ingredient/kg body weight); the second dog (12.3 kg) was treated with 2.5 mL of the test solution at four sites, each site receiving approximately 0.625 mL, along the dorsal thoracic and lumbar spine area (21 mg active ingredient/kg body weight). Samples of hair, skin surface residue, and skin taken from the application sites and/or distal body regions of the dogs at four intervals between 7 and 56 days after treatment demonstrated the migration of (14)C radioactivity from the application sites to distal areas of the canine haircoat and skin. The (14)C radioactivity concentrations in the skin biopsy and stratum corneum samples diminished steadily over 56 days after treatment. Microautoradiography of the skin showed focal concentrations of radioactivity in the superficial epidermis, hair follicles, and sebaceous glands. The presence of imidacloprid-derived radioactivity within hair follicles and sebaceous glands and on the skin surface is in good agreement with the reported efficacy of imidacloprid against fleas on dogs and cats for up to 1 month despite posttreatment bathing, shampooing, and/or swimming.
authors.affiliation: Bayer Animal Health, 12809 Shawnee Mission Parkway, Shawnee Mission, KS 66216, USA. harish.chopade@bayer.com
authors.forename: Harish
authors.initials: H
authors.lastname: Chopade
authors.forename: David
authors.initials: D
authors.lastname: Eigenberg
authors.forename: Eric
authors.initials: E
authors.lastname: Solon
authors.forename: Paul
authors.initials: P
authors.lastname: Strzemienski
authors.forename: Joe
authors.initials: J
authors.lastname: Hostetler
authors.forename: Terry
authors.initials: T
authors.lastname: McNamara
mesh_terms: D000287:Administration, Topical; D000818:Animals; D004285:Dogs / Q000378:metabolism*; D005260:Female; D007093:Imidazoles / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007306:Insecticides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012867:Skin / Q000737:chemistry / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid