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Therapeutic response to pentoxifylline and its active metabolites in dogs with dermatomyositis
Author(s) -
Rees C. A.,
Boothe D. M.,
Wilkie S.
Publication year - 2002
Publication title -
veterinary dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.744
H-Index - 60
eISSN - 1365-3164
pISSN - 0959-4493
DOI - 10.1046/j.1365-3164.2002.00298_18.x
Subject(s) - pentoxifylline , medicine , dermatomyositis , gastroenterology
The purpose of this study was to determine a therapeutic dose for Trental® (pentoxifylline) when used to treat dogs with dermatomyositis. Eleven dogs diagnosed with dermatomyositis based on history, physical examination and biopsy were treated with pentoxifylline (46.5 ± 8 mg kg −1 divided twice daily) with food. Biweekly for 3 months, urinalyses, complete blood counts, serum chemistries and therapeutic drug monitoring (peak collected at 3 h and trough before the next dose) were collected. Dermatological lesions were assessed during each visit and given a score (0 = nonexistent, 1 = mild, 2 = moderate and 3 = severe). Serum concentrations of pentoxifylline (pentoxy) and metabolites 1 (M1) and 5 (M5) were measured by high‐performance liquid chromatography. Descriptive statistics were generated for the drug concentrations. Although all animals responded to therapy, the time to initial response (skin lesions changed to a lower score compared with the initial visit) varied between all of the dogs. The range was 4 to 10 weeks, with a median of 6 weeks of therapy. Laboratory tests did not differ between the first and last sampling times (month 3). Pentoxifylline and M1 and M5 concentrations (ng mL −1 ) for the 11 dogs varied between dog and across time for each dog. In general, concentrations for all three compounds were detectable only with peak (3 h) samples. Concentrations for M5 were highest for all dogs at each sampling time, and appeared to be the most consistent and characterized by the least variability. Concentrations were not detectable in one dog for pentoxy or M1 at any time, but were detectable for M5. Data for this dog were not included. Based on the response to therapy in this study, a dose 25 mg kg −1 of pentoxifylline administered every 12 h appears to be an effective beginning dose. Because of variability in disposition, including metabolite formation, monitoring of pentoxifylline may not offer a therapeutic advantage. Funding: Collie Club of America Foundation.