fludrocortisone acetate
Florinef

Available forms
Available by prescription only
Tablets: 0.1 mg

Indications and dosages
 Adrenal insufficiency or Addison’s disease (partial replacement), salt-losing adrenogenital syndrome. Adults: 0.1 to 0.2 mg P.O. daily.
Children: 0.05 to 0.1 mg P.O. daily.
 Orthostatic hypotension in diabetic patients. ◇ Adults: 0.1 to 0.4 mg P.O. daily.
 Orthostatic hypotension from levodopa therapy. ◇ Adults: 0.05 to 0.2 mg P.O. daily.

Pharmacodynamics
Adrenal hormone replacement: Fludrocortisone, a synthetic glucocorticoid with potent mineralocorticoid activity, is used for partial replacement of steroid hormones in adrenocortical insufficiency and in salt-losing forms of congenital adrenogenital syndrome. In treating adrenocortical insufficiency, an exogenous glucocorticoid must also be administered for adequate control. (Cortisone or hydrocortisone are usually the drugs of choice for replacement because they produce both mineralocorticoid and glucocorticoid activity.) Fludrocortisone is administered on a variable schedule ranging from three times weekly to twice daily, depending on individual requirements.

Pharmacokinetics
Absorption: Absorbed readily from the GI tract.
Distribution: Removed rapidly from blood and distributed to muscle, liver, skin, intestines, and kidneys. It has a plasma half-life of about 3.5 hours. It’s extensively bound to plasma proteins (transcortin and albumin). Only the unbound portion is active. Adrenocorticoids are distributed into breast milk and through the placenta.
Metabolism: Metabolized in the liver to inactive glucuronide and sulfate metabolites.
Excretion: Inactive metabolites and small amounts of unmetabolized drug are excreted by the kidneys. Insignificant quantities of drug are also excreted in feces. Biologic half-life is 18 to 36 hours.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and those with systemic fungal infections.
  Use cautiously in patients with hypothyroidism, cirrhosis, ocular herpes simplex, emotional instability, psychotic tendencies, nonspecific ulcerative colitis, diverticulitis, fresh intestinal anastomoses, peptic ulcer, renal insufficiency, hypertension, osteoporosis, and myasthenia gravis.

Interactions
Drug-drug. Amphotericin B, thiazide diuretics: May enhance hypokalemia. Monitor electrolytes.
Barbiturates, phenytoin, rifampin: Decreases corticosteroid effects. Monitor patient carefully.
Cardiac glycosides: Increases risk of toxicity if hypokalemia occurs. Monitor patient closely.
Isoniazid, salicylates: Increases metabolism of these drugs. Monitor patient for drug effects.
Drug-food. Sodium-containing drugs or foods: May increase blood pressure. Sodium intake may need adjustment.

Adverse reactions
CV: sodium and water retention, hypertension, cardiac hypertrophy, edema, heart failure.
Metabolic: hypokalemia.
Skin: bruising, diaphoresis, urticaria, allergic rash.

Effects on lab test results
• May increase serum sodium level. May decrease potassium level.

Overdose and treatment
Acute toxicity occurs as an extension of the therapeutic effect, such as disturbances in fluid and electrolyte balance, hypokalemia, edema, hypertension, and cardiac insufficiency.
 In acute toxicity, administer symptomatic treatment and correct fluid and electrolyte imbalance.

Special considerations
• Severe hypoglycemia tends to develop in addisonian patients within 3 hours of glucose tolerance tests. Perform only if needed in these patients.
• Use only with other supplemental measures, such as glucocorticoids, control of electrolytes, and control of infection.
• Supplemental dosages may be required in times of physiologic stress from serious illness, trauma, or surgery.
• Monitor patient for significant weight gain, edema, hypertension, or severe headaches.
Pediatric patients
• Long-term use in children and adolescents may delay growth and maturation. Use cautiously.

Patient education
• Teach patient to recognize signs of electrolyte imbalance: muscle weakness, paresthesia, numbness, fatigue, anorexia, nausea, altered mental status, increased urination, altered heart rhythm, severe or continuing headaches, unusual weight gain, or swelling of the feet.
• Tell patient to take missed doses as soon as possible, unless it’s almost time for the next dose, and not to double the dose.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use