Fludrocortisone

Introduction

Fludrocortisone is a steroid with potent mineralocorticoid activity. It is used to treat:

• adrenocortical insufficiency
• postural hypotension
• adrenogenital syndrome

Generic Name	HA Code	Legal Classification
Fludrocortisone Acetate Tablet 100mcg	FLUD01	P1S1S3

Brand Name	HK Reg Number	Active Ingredients
FLORINEF TABLET 0.1mg	HK-00036	fludrocortisone acetate

Mechanism of Action

Fludrocortisone is a corticosteroid with glucocorticoid and highly potent mineralocorticoid activity.

Dosage

Fludrocortisone is used, usually with hydrocortisone, for replacement therapy in adrenocortical insufficiency.

Replacement therapy in adrenal insufficiency	Oral: 50-300 micrograms daily
severe orthostatic hypotension	Oral: 50-300 micrograms daily

It is also used ear drops in concentration of 0.1%.

Side Effects

Fludrocortisone acetate has glucocorticoid actions about 10 times as potent as hydrocortisone and mineralocorticoid effects more than 100 times as potent. Adverse effects are mainly those due to mineralocorticoid activity:

• sodium and water retention
• swelling due to fluid retention (oedema)
• hypertension
• increased excretion of potassium leading to hypokalaemia
• heart failure may be induced in susceptible patients

Other side-effects include:

steroid-induced diabetes	Raised blood sugar level
Osteoporosis, muscle wasting and weakenss	which is a danger, particularly in the elderly, as it can result in osteoporotic fractures for example of the hip or vertebrae
Susceptibility to infection
Disturbances of the gut	Indigestion, peptic ulcer, distension of the abdomen
Suppression of growth in children
Endocrine side effects	menstrual irregularities , hirsutism (increased hair growth), weight gain
Neuropsychiatric side effects	aggravation of schizophrenia, aggravation of epilepsy, insomnia, irritability, depression
Dermatological side effects	easy bruising, impaired wound healing, thinning of skin and stretch marks
Ophthalmic side effects	glaucoma, partial loss of vision due to opacity in the lens of the eye (cataracts)

Pharmacokinetics

Fludrocortisone is readily absorbed from the gastrointestinal tract. The plasma half-life is about 3.5 hours, but fludrocortisone has a more prolonged biological half-life of 18 to 36 hours.

Drug Management

Monitoring

• Elderly (close supervision required particularly on long-term treatment)
• Frequent monitoring required if history of tuberculosis (or X-ray changes)
• blood sugar level, blood pressure, mood change
• monitoring of the fluid intake and output, and daily weight records may give early warning of fluid retention
• Sodium intake may need to be reduced and calcium and potassium supplements may be necessary
• Back pain may signify osteoporosis
• Plasma renin, sodium, and potassium is checked through blood tests to verify that the correct dosage is reached

Drug interaction

Interactions do not generally apply to steroid used for topical action including inhalation, unless specified.

Drugs given with steroid	Potential adverse drug interactions	NSAIDs	Increased risk of gastro-intestinal bleeding
Rifampicin	Accelerate metabolism of fludrocortisone so reduce its effects
Antidiabetics	Antagonize hypoglycemic effect, so may need to increase antidiabetic dosage
Antiepileptics such as carbamazepine, phenobarbitone, phenytoin	Accelerate metabolism of fludrocortisone so reduce its effects
Antifungal e.g. amphotericin	Increased risk of hypokalaemia
Antiviral e.g ritonavir	Increase plasma concentration of steroid – increased risk of adrenal suppression
Digoxin	Increased risk of hypokalaemia
Diuretics