Dexamethasone Sodium Phosphate Solution for Control of Feline Pruritus

In the literature

McClintock D, Austel M, Gogal RM Jr, Banovic F. Oral dexamethasone sodium phosphate solution significantly reduces pruritus and clinical lesions in feline hypersensitivity dermatitis: an open-label study. Vet Dermatol. 2021;32(5):497-e137.

The Research …

Feline hypersensitivity dermatitis is allergic skin disease caused by exposure to flea, food, and/or environmental allergens, whereas feline atopic skin syndrome (FASS) is allergic skin disease specifically associated with environmental allergens. Short-term glucocorticoids often result in rapid control of hypersensitivity dermatitis; however, oral administration of tablets to cats can be challenging, and there are no liquid oral glucocorticoids labeled for pruritus management. Injectable glucocorticoids are commonly used, but long-term use can be associated with increased risk for deleterious effects (eg, diabetes mellitus, exacerbated heart disease, iatrogenic hyperadrenocorticism). 

This study aimed to determine the systemic absorption of injectable dexamethasone sodium phosphate (DexSP) when administered to healthy cats as an oral solution (phase 1, n = 7) and to evaluate the efficacy of oral DexSP solution in reducing pruritus and lesions in cats with hypersensitivity dermatitis (phase 2, n = 12). Serum dexamethasone concentrations were measured using an ELISA test. DexSP was absorbed in all cats in phase 1, but a wide variation in serum concentrations was noted at all time points. 

All cats in phase 2 that completed the nonblinded part of the study were diagnosed with FASS; 11 cats exhibited self-induced alopecia. All cats had a decrease in pruritus and clinical lesions after 20 to 31 days of treatment, with a significant decrease in pruritus (79%) and clinical lesions (59.5%) between visits. 

One cat in phase 1 experienced ptyalism. Four cats in phase 2 had an adverse effect (eg, polyphagia, polydipsia, sneezing, lethargy, inappropriate urination), and 1 affected cat had hyperglycemia and glucosuria at the end of the study; however, none of the adverse effects warranted intervention. 

Limitations of this study included not being blinded or controlled, including a small number of subjects, having a short study duration, and using an ELISA test not validated for use in cats. Double-blinded, randomized, and controlled studies with larger numbers of subjects for a longer study duration are needed to validate these findings.

… The Takeaways

Key pearls to put into practice:

• Feline hypersensitivity dermatitis is common, and oral medications can be difficult to administer in cats. DexSP in a liquid form may be an alternative therapeutic option.

• An individual cat may not respond to the DexSP preparation due to variable absorption when administered orally.

• Significant improvement in pruritus and lesion scores for cats diagnosed with FASS was reported after 20 to 31 days of treatment with DexSP solution; however, these cats were given 0.2 mg/kg every 24 hours. In cats, oral dexamethasone tablets should be given at 0.1-0.2 mg/kg every 24 hours and tapered to a maintenance dose of 0.05 mg/kg every 48 to 72 hours to reduce the occurrence of adverse events, as dexamethasone is 6 to 10 times as potent as prednisolone. Reduction to a maintenance dosage is advisable until a long-term study is performed.