THE PET PHARMACY By Wendy C. Brooks, DVM, DipABVP Educational Director, VeterinaryPartner.com

(for veterinary information only)

Brand Name: Florinef

Available in 0.1 mg tablets

Uses of this Medication

There is really only one use for this medication: the treatment of 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 that is also showing weakness, vomiting, diarrhea or appetite loss should be seen by a veterinarian and have his/her sodium and/or potassium balance checked.

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 name Percorten®) - see Addison's disease for more details.

How this Medication Works

Fludrocortisone acetate acts on the kidney to conserve sodium and excrete potassium. Naturally-occurring mineralocorticoids would act similarly if there are adequate quantities.

Side Effects

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

An overdose of fludrocortisone acetate could lead to high blood pressure, excess sodium retention and associated edema, 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 thiazide type diuretic (usually used in the treatment of oxalate bladder stones) or with the anti-fungal agent Amphotericin B.

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 medication called DOCP (brand name Percorten®) is available. Injections are given approximately every 25 days and many experts feel that control of Addison’s disease is superior with DOCP injections. In larger dogs, it is often true that these injections are less expensive than oral (pills) Florinef therapy. DOCP is an option.

It is our policy not to give dosing information over the Internet.

Date Published: 1/1/2001
Date Reviewed/Revised: 02/05/2010