The pharmacokinetics of methimazole in a novel lipophilic formulation administered transdermally to healthy cats.
N Z Vet J
; 62(4): 208-13, 2014 Jul.
Article
em En
| MEDLINE
| ID: mdl-24350893
AIM: To determine the pharmacokinetics of a novel lipophilic formulation of transdermal methimazole compared to oral carbimazole. METHODS: Healthy cats received 5â
mg carbimazole orally every 12 hours for 13 treatments (n=6), then received transdermal methimazole (n=5) at a dose of 5â
mg, then 10â
mg, once daily on the pinna for 7 days, with 21 days between treatments. Concentrations of methimazole in serum over 24 hours and at 148 hours were determined by high performance liquid chromatography. RESULTS: Concentrations of methimazole in serum for the first 24 hours were not reliably detected in all cats treated with 5â
mg methimazole transdermally, while for those receiving 5â
mg carbimazole orally and 10â
mg methimazole transdermally all cats had detectable concentrations of methimazole in serum. The maximum concentration and area under the curve were lower in cats receiving 10â
mg methimazole transdermally (108 (SD 25) ng/mL and 2544 (SD 216) mg-hour/mL, respectively) than those receiving 5â
mg oral carbimazole (355 (SD 113) ng/mL and 31,866 (SD 439) ng-hour/mL, respectively) (p<0.05). The time at maximal concentration and elimination half-life were longer for 10â
mg transdermal methimazole (5.2 (SD 1.1) hours and 13 (SD 3) hours, respectively) compared to 5â
mg oral carbimazole (2.1 (SD 1.6) hours and 5.1 (SD 1.2) hours, respectively). At 148 hours, mean concentrations of methimazole in serum were higher in cats receiving 10â
mg methimazole transdermally (506 (SD 165) ng/mL) than for 5â
mg oral carbimazole (255 (SD 28) ng/mL) or 5â
mg transdermally (204 (SD 76) ng/mL). The mean relative bioavailability of 10â
mg transdermal methimazole compared to oral carbimazole was 48 (min 43, max 55)%. CONCLUSION: Transdermal methimazole at a dose of 10â
mg administered to the pinnae of healthy cats once daily in a novel lipophilic formulation has half the relative bioavailablity compared to 5â
mg oral carbimazole. CLINICAL RELEVANCE: Transdermal methimazole can be absorbed from the skin of healthy cats.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Antitireóideos
/
Gatos
/
Metimazol
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
N Z Vet J
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Nova Zelândia
País de publicação:
Reino Unido