New developments in the treatment of Addison’s disease


Recently florinef® (fludrocortisone) has become difficult to obtain. Generic products with uncertain bioavailability are currently prohibitively expensive. Coincidentally a new product, Zycortal®, has been launched by Dechra® and is the UK’s only veterinary registered treatment for hypoadrenocorticism. It is a prolonged release subcutaneous injection containing desoxycortone pivalate (DOCP).

There are some differences between DOCP and fludrocortisone. Fludrocortisone has potent mineralocorticoid (e.g. aldosterone) activity but also some glucocorticoid (e.g. cortisol) activity. As the dose of fludrocortisone administered is dictated by the mineralocorticoid requirement, the dose of glucocorticoid is difficult to precisely control. It is for this reason in some dogs, undesired signs of glucocorticoid excess can occur, whilst others require additional glucocorticoid therapy.

DOCP is a pure mineralocorticoid with no glucocorticoid activity. Therefore, in all cases, it is essential to administer a glucocorticoid concurrently (normally prednisolone). It is a subcutaneous injection which lasts around 25 days. Similar to fludrocortisone, the dose is titrated to effect based on electrolyte results. Dechra® provide detailed guidelines regarding the dose and monitoring of DOCP therapy. The dose of prednisolone can be independently titrated to effect.

In dogs previously diagnosed with hypoadrenocorticism and currently being treated with fludrocortisone, unpublished studies by Dechra® suggest transition to DOCP therapy is possible. Dechra® recommend that DOCP is administered before phasing out fludrocortisone over a period of 2-3 days. Prednisolone must be commenced before fludrocortisone is discontinued in dogs that did not previously require both.

It is unclear whether treatment with DOCP and prednisolone results in a better long-term prognosis compared to treatment with fludrocortisone +/- prednisolone, however in general, whether treated with DOCP or fludrocortisone, the prognosis for most dogs with hypoadrenocorticism is excellent.

If you have any questions about the use of DOCP feel free to contact one of our Internal Medicine clinicians for further advice.

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