By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com
Brand Name: Florinef
Available in 0.1 mg tablets
Uses of this Medication
There is really only one use for this medication: treating hypoadrenocorticism (Addison's disease). In this disease, the adrenal gland is unable to produce hormones called mineralocorticoids. In the normal animal, these hormones are responsible for the balance of sodium and potassium, and without these hormones a life-threatening circulatory shock ultimately results. Fludrocortisone acetate is a mineralocorticoid that can be given as a tablet to animals or people with Addison's disease to prevent this circulatory crisis.
It should be noted that an Addisonian crisis is an emergency and that while fludrocortisone acetate is appropriate for prevention, it does not work fast enough in a crisis. An animal known to have Addison's disease who is also showing weakness, vomiting, diarrhea or appetite loss should be seen by a veterinarian and have the sodium/potassium balance checked and should be seen by a veterinarian.
Fludrocortisone dosing has a trial and error aspect and it can be difficult to get to the best dose for a given patient. The process of trying a dose and testing electrolytes (i.e. sodium and potassium) can become expensive, especially in larger dogs. Many people prefer a monthly injection of desoxycorticosterone pivalate (more commonly known as DOCP or by the brand names Percorten® or Zycortal®. See more about it on the Addison's disease page.
How this Medication Works
Fludrocortisone acetate acts on the kidney to conserve sodium and excrete potassium. Naturally-occurring mineralocorticoids would act similarly if there were adequate quantities.
Fludrocortisone acetate has glucocorticoid properties in addition to its mineralocorticoid properties. This means that it acts in a fashion similar to that of prednisone and similar side effects can be observed. More specifically:
- Excessive thirst and urine production
- Weight gain and excessive appetite
- Hair loss/poor coat
Review the prednisone section for more information on side effects.
An overdose of fludrocortisone acetate could lead to high blood pressure, excess sodium retention and associated edema, and weakness due to low potassium levels. Monitoring with periodic blood levels of sodium and potassium is crucial, especially when the patient is just beginning therapy. The dose of medication will be dependent on these blood levels. A typical monitoring schedule would be electrolytes every 1 to 2 weeks until values are stable, followed by testing quarterly.
Interactions with other Drugs
Blood potassium levels may drop dangerously low if this medication is used concurrently with a diuretic (such as furosemide or a member of the thiazide class of diuretics) or with the anti-fungal agent Amphoterecin B.
Fludrocortisone may also make diabetic patients more resistant to their usual dose of insulin.
Prednisone is generally not required in conjunction with fludrocortisone except during times of stress. This is because fludrocortisone acetate has adequate glucocorticoid properties on its own under ordinary circumstances, but not under stressful circumstances.
Concerns and Cautions
Currently, an injectable mineralocorticoid called DOCP may be given approximately every 25 days. Many experts feel that control of Addison's disease is superior with DOCP injections, though a corticosteroid such as prednisone generally must be given concurrently. In larger dogs, it is often true that these injections are less expensive than oral fludrocortisone acetate therapy. DOCP is an option to be aware of.
Fludrocortisone acetate is also available through compounding pharmacies in custom-made doses which, for larger dogs, often prove more cost-effective than multiple 0.1 mg manufactured tablets.
It is our policy not to give dosing information over the Internet.