Ex-vivo study of the percutaneous absorption of a tramadol formulation through feline inner pinna skin. (10th December 2022)

• Record Type: Journal Article
• Authors: Beuve, Mathilde Sainte; Espana, Bernadette; Pin, Didier; Prouillac, Caroline
• Is Part Of: Research in veterinary science. Volume 151(2022)
• Page Start: 57
• Page End: 63
• Publication Date: 2022-12-10
• Subjects: Feline -- Tramadol -- Transdermal administration -- Ex vivo; Veterinary medicine -- Periodicals; Veterinary Medicine -- Periodicals; Médecine vétérinaire -- Périodiques; Médecine vétérinaire -- Recherche -- Périodiques; Diergeneeskunde; 636.089
• DOI: 10.1016/j.rvsc.2022.05.013
• Languages: English
• ISSNs: 0034-5288

Abstract

Abstract: Objectives: Oral medication of small animals, particularly cats, is often challenging. The transdermal route may provide an easier option for owners to administer chronic treatment. Tramadol is an analgesic mainly used in humans; it is also commonly used in dogs, despite some controversy over its clinical efficacy. Recent studies have suggested that tramadol is efficacious for pain management in cats. In cats, the inner pinna is the most commonly used site for transdermal drug therapy; the use of this site has been validated in experimental studies of methimazole and mirtazapine treatment. This ex vivo study aimed to characterise the percutaneous absorption pharmacokinetics of a formulation of tramadol in Pentravan through feline inner pinna skin. Methods: High-performance liquid chromatography was used to assess the stability of the tramadol formulation (100 mg/ml in Pentravan) over three months at room temperature. Forced degradation was also assessed in neutral, acidic, alkaline, and oxidative conditions. A Franz cell system was employed to evaluate percutaneous absorption of a finite dose of tramadol. Results: The tramadol formulation was stable for three months at room temperature. Tramadol penetrated through ex vivo feline inner pinna skin, but considerable intra- and inter-individual variability in kinetics was observed. Comparison with another vehicle, Lipoderm, revealed no significant difference in the percutaneous absorption of tramadol. Conclusions and relevance: The Pentravan formulation assessed in this study supported tramadol absorption across the feline inner ear skin. In vivo studies are necessary to evaluate the pharmacokinetics and efficacy of this formulation. Highlights: The transdermal route in cats represents an interesting alternative to the oral route. Analgesics authorized in medicine are limited in cats. Formulation of tramadol in Pentravan is stable over three months at room temperature. Tramadol penetrated through ex vivo feline inner pinna skin with considerable intra- and inter-individual variability.