Fludrocortisone

Uses

Used for oral mineralocorticoid replacement therapy in:

• Primary and secondary adrenocortical insufficiency in Addison’s disease
• Salt losing adrenogenital syndrome
• Postural hypotension

Fludrocortisone is also used to associated treatment for these conditions: Otitis Externa, Otitis Media (OM), Primary adrenocortical insufficiency, Secondary adrenocortical insufficiency, Salt-losing Androgenital syndrome

How Fludrocortisone works

The main endogenous mineralocorticoid, aldosterone, is produced in the zona glomerulosa of the adrenal cortex - it acts on mineralocorticoid receptors in the kidneys to increase sodium reabsorption and potassium excretion, which in turn helps to regulate plasma electrolyte composition and blood pressure. In conditions of adrenal insufficiency, such as Addison’s disease, aldosterone is not produced (or is produced in insufficient quantities) and must be replaced by exogenous mineralocorticoids such as fludrocortisone.

Fludrocortisone binding to mineralocorticoid receptors causes alterations to DNA transcription and translation of proteins that result in an increased density of sodium channels on the apical side of renal tubule cells and an increased density of Na^{+ These increases in receptor density result in increased plasma sodium concentrations, and thus increased blood pressure, as well as a decreased plasma potassium concentration. Fludrocortisone may also exert a direct effect on plasma sodium levels via action at the Na+}

Fludrocortisone also acts on glucocorticoid receptors, albeit with a much lower affinity - the glucocorticoid potency of fludrocortisone is approximately 5-10 times that of endogenous cortisol, whereas its mineralocorticoid potency is 200-400 times greater.

Dosage

Fludrocortisone dosage

Primary and secondary Adrenocortical Insufficiency in Addison’s disease: Usual dose may range from 0.2 mg 3 times weekly to 0.2 mg daily. If hypertension occurs, reduce dosage to 0.05 mg daily. Administer concomitantly with Cortisone or hydrocortisone.

Salt-Losing Adrenogenital Syndrome: 0.1 to 0.2 mg/day.

Postural Hypotension: 0.1-0.4 mg daily to diabetic patients with postural hypotension; 0.05-0.2 mg daily to patients with postural hypotension secondary to Levodopa therapy.

Side Effects

Most adverse reactions are caused by the drug’s mineralocorticoid activity (retention of sodium andwater) include erythema, purpura, vertigo, pancreatitis, increased intraocular pressure, muscular weakness, hypertension, edema, cardiac enlargement, congestive heart failure, steroid myopathy, peptic ulcer, osteoporosis, convulsions, menstrual irregularities, potassium loss, hypokalemic alkalosis, allergic and anaphylactic reaction etc. When Fludrocortisones is used in the small dosages recommended, side effects are not usually a problem; however the above mentioned unwanted effects should be kept in mind, particularly when Fludrocortisones is used over a prolonged period of time or in conjunction with cortisone or a similar glucocorticoid.

Toxicity

The oral LD₅₀ of fludrocortisone in rats is >1g/kg. Acute overdosage of fludrocortisone is likely to result in symptoms consistent with its adverse effect profile. Patients receiving a single large dose should be treated with plenty of water by mouth and should undergo monitoring of serum electrolytes, particularly potassium and sodium, and be treated appropriately for any developing imbalances.

Precaution

Because of its marked effect on sodium retention, the use of Fludrocortisone in the treatment of conditions other than those indicated herein is not advised. Fludrocortisone should be used with caution in patients suffering from different infections (like tuberculosis, measles, chicken pox, herpes zoster or threadworm infestation), congestive cardiac failure, hypertension, renal insufficiency, osteoporosis, drug-induced secondary adrenocortical insufficiency, peptic ulcer, intestinal anastomosis and ulcerative colitis.

Interaction

Interactions can occur with following drugs: Amphotericin B, potassium depleting diuretics, anticholinesterases, anticoagulants, antidiabetics. Antitubercular drugs, cyclosporine, digitalis glycosides, oral contraceptives and ketoconazole .

Food Interaction

• Limit salt intake. Excessive intake of salt can result in hypertension and edema.

Fludrocortisone Cholesterol interaction

[Moderate] Corticosteroids may elevate serum triglyceride and LDL cholesterol levels if used for longer than brief periods.

Patients with preexisting hyperlipidemia may require closer monitoring during prolonged corticosteroid therapy, and adjustments made accordingly in their lipid-lowering regimen.

Fludrocortisone Hypertension interaction

[Moderate] Corticosteroids may cause hypernatremia, hypokalemia, fluid retention, and elevation in blood pressure.

These mineralocorticoid effects are most significant with fludrocortisone, followed by hydrocortisone and cortisone, then by prednisone and prednisolone.

The remaining corticosteroids, betamethasone, dexamethasone, methylprednisolone, and triamcinolone, have little mineralocorticoid activities.

However, large doses of any corticosteroid can demonstrate these effects, particularly if given for longer than brief periods.

Therapy with corticosteroids should be administered cautiously in patients with preexisting fluid retention, hypertension, congestive heart failure, and

Dietary sodium restriction and potassium supplementation may be advisable.

Fludrocortisone Drug Interaction

Unknown: diphenhydramine, diphenhydramine, duloxetine, duloxetine, pregabalin, pregabalin, levothyroxine, levothyroxine, acetaminophen, acetaminophen, cyanocobalamin, cyanocobalamin, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol, ondansetron, ondansetron, cetirizine, cetirizine

Fludrocortisone Disease Interaction

Major: GI perforation, infections, PUD, vaccinationModerate: (+) tuberculin test, cirrhosis, depression/psychoses, diabetes, electrolyte imbalance, fluid retention, hyperadrenocorticalism, hyperlipidemia, hypothyroidism, liver disease, MI, myasthenia gravis, myopathy, ocular herpes simplex, ocular toxicities, osteoporosis, scleroderma, strongyloidiasis, thromboembolism

Volume of Distribution

The apparent volume of distribution of fludrocortisone is 80-85 L. Distribution into CSF appears minimal - the observed ratio of CSF drug concentration versus plasma drug concentration is 1:6.

Elimination Route

Absorption of fludrocortisone following oral administration is rapid and complete. Pharmacokinetic studies have estimated the C_max to be 0.0012 to 0.20 μg/L with a T_max between 0.5 and 2 hours. The AUC_0-∞ of fludrocortisone after oral administration has been variably estimated to be between 1.22 to 3.07 μg.h/L.

Half Life

The plasma half-life of fludrocortisone has been variably reported to be between 1-3.5 hours, though prescribing information gives an approximate half-life of 18-36 hours.

Clearance

Population pharmacokinetics have estimated the plasma clearance of fludrocortisone to be 40.8 L/h.

Elimination Route

Approximately 80% of an administered dose of fludrocortisone shows up in the urine, with the other 20% likely eliminated via fecal or biliary route.

Pregnancy & Breastfeeding use

Pregnancy category C. There are no adequate and well-controlled studies in pregnant women. Fludrocortisone is only recommended for use during pregnancy when there are no alternatives and benefit outweighs risk.

Lactation: There are no data on the excretion of fludrocortisone into human milk. However, corticosteroids (systemic therapy) are distributed into breast milk and could cause growth suppression and/or other adverse effects in nursing infants. The manufacturer recommends that caution be used when administering Fludrocortisone to nursing women.

Contraindication

In case of adrenal insufficiency, no absolute contraindications are applicable. In the treatment of non-endocrine diseases where pharmacological dose are more likely to be used, the contraindications to be considered carefully. Relative contraindications include: systemic fungal infection, hypersensitivity to Fludrocortisone, diabetic mellitus, osteoporosis and acute infection.

Acute Overdose

Overdose is unlikely; however, treatment of overdose is by supportive and symptomatic therapy.

Storage Condition

Store in a cool and dry place, protected from light.

Innovators Monograph

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