Mineralocorticoids

Chemistry and Pharmacodynamics

Chemical structure

Fludrocortisone is the primary drug in this class.

• Synthetic mineralocorticoid
• Fluorinated analog of cortisol Cortisol Glucocorticoids

Mechanism of action

• Mimics the effect of aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia → acts on the mineralocorticoid receptors Receptors Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors (in cytoplasm) in the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy:
  • Distal convoluted tubule Distal convoluted tubule The portion of renal tubule that begins from the enlarged segment of the ascending limb of the loop of henle. It reenters the kidney cortex and forms the convoluted segments of the distal tubule. Gitelman Syndrome
  • Collecting duct Collecting duct Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of bellini) which opens on the summit of the papilla. Renal Cell Carcinoma
• ↑ DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure transcription Transcription Transcription of genetic information is the first step in gene expression. Transcription is the process by which DNA is used as a template to make mRNA. This process is divided into 3 stages: initiation, elongation, and termination. Stages of Transcription and translation Translation Translation is the process of synthesizing a protein from a messenger RNA (mRNA) transcript. This process is divided into three primary stages: initiation, elongation, and termination. Translation is catalyzed by structures known as ribosomes, which are large complexes of proteins and ribosomal RNA (rRNA). Stages and Regulation of Translation of proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis for channels Channels The Cell: Cell Membrane on renal tubule cells:
  • ↑ Na⁺ channels Channels The Cell: Cell Membrane (apical side) → ↑ Na⁺ reabsorption → water reabsorption
  • ↑ Na⁺/K⁺ ATPase (basolateral side) → ↑ K⁺ excretion through renal outer medullary potassium Potassium An element in the alkali group of metals with an atomic symbol k, atomic number 19, and atomic weight 39. 10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance. Hyperkalemia (ROMK) channels Channels The Cell: Cell Membrane (apical side)

Physiologic effects

• ↑ Plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products Na⁺ and water retention → ↑ blood pressure
• ↓ Plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products K⁺
• Additionally, has glucocorticoid activity and effects

Pharmacokinetics

Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption

• Administered orally
• Rapid and complete

Distribution

• 70%‒80% is protein bound:
  • Albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests
  • Corticosteroid-binding globulin Corticosteroid-Binding Globulin Glucocorticoids
• The fluorinated structure protects from oxidation (11-beta-hydroxysteroid dehydrogenase isoenzyme) and inactivation in the kidney → allows for mineralocorticoid potency

Metabolism and excretion

• Hepatic metabolism
• Excretion:
  • Primarily in urine
  • Minority in feces

Indications

Although fludrocortisone has glucocorticoid activity, it is primarily used for its mineralocorticoid activity (particularly in conditions with inadequate aldosterone Aldosterone A hormone secreted by the adrenal cortex that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium. Hyperkalemia production).

• In conjunction with a glucocorticoid:
  • Adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease
  • Congenital Congenital Chorioretinitis adrenal hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation
  • Septic shock Septic shock Sepsis associated with hypotension or hypoperfusion despite adequate fluid resuscitation. Perfusion abnormalities may include, but are not limited to lactic acidosis; oliguria; or acute alteration in mental status. Sepsis and Septic Shock that has not responded to IV fluid resuscitation Resuscitation The restoration to life or consciousness of one apparently dead. . Neonatal Respiratory Distress Syndrome (off-label use)
• In conjunction with ↑ salt and/or fluid intake (off-label use):
  • Orthostatic hypotension Orthostatic hypotension A significant drop in blood pressure after assuming a standing position. Orthostatic hypotension is a finding, and defined as a 20-mm hg decrease in systolic pressure or a 10-mm hg decrease in diastolic pressure 3 minutes after the person has risen from supine to standing. Symptoms generally include dizziness, blurred vision, and syncope. Hypotension
  • Postural orthostatic tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children syndrome (POTS)
  • Cerebral salt wasting

Adverse Effects and Contraindications

Adverse effects

There are many side effects of fludrocortisone therapy, notably:

• Cardiovascular:
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Fluid retention and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • Decompensated heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
• Endocrine and electrolyte disturbances:
  • Hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus and diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus
  • Weight gain
  • Cushing syndrome Cushing syndrome A condition caused by prolonged exposure to excess levels of cortisol (hydrocortisone) or other glucocorticoids from endogenous or exogenous sources. It is characterized by upper body obesity; osteoporosis; hypertension; diabetes mellitus; hirsutism; amenorrhea; and excess body fluid. Endogenous Cushing syndrome or spontaneous hypercortisolism is divided into two groups, those due to an excess of adrenocorticotropin and those that are acth-independent. Paraneoplastic Syndromes
  • Growth suppression Suppression Defense Mechanisms
  • Hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia
  • Metabolic alkalosis Alkalosis A pathological condition that removes acid or adds base to the body fluids. Respiratory Alkalosis
• CNS:
  • Delirium Delirium Delirium is a medical condition characterized by acute disturbances in attention and awareness. Symptoms may fluctuate during the course of a day and involve memory deficits and disorientation. Delirium
  • Psychosis
  • ↑ Intracranial pressure Intracranial Pressure Idiopathic Intracranial Hypertension
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
• Dermatologic:
  • Acne
  • Hyperpigmentation Hyperpigmentation Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance. Malassezia Fungi
  • Striae
  • Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation
  • Delayed wound healing Wound healing Wound healing is a physiological process involving tissue repair in response to injury. It involves a complex interaction of various cell types, cytokines, and inflammatory mediators. Wound healing stages include hemostasis, inflammation, granulation, and remodeling. Wound Healing
• Musculoskeletal:
  • Myopathy Myopathy Dermatomyositis
  • Osteonecrosis
  • Osteoporosis Osteoporosis Osteoporosis refers to a decrease in bone mass and density leading to an increased number of fractures. There are 2 forms of osteoporosis: primary, which is commonly postmenopausal or senile; and secondary, which is a manifestation of immobilization, underlying medical disorders, or long-term use of certain medications. Osteoporosis
• GI: ulcers
• Ophthalmic:
  • Glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma
  • Cataracts
• Withdrawal:
  • Chronic therapy results in hypothalamic-pituitary-adrenal (HPA)-axis suppression Suppression Defense Mechanisms.
  • Abrupt discontinuation may cause adrenal insufficiency Adrenal Insufficiency Conditions in which the production of adrenal corticosteroids falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the adrenal glands, the pituitary gland, or the hypothalamus. Adrenal Insufficiency and Addison Disease.

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation and precautions

• Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation:
  • Systemic fungal infection
  • Previous allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction to corticosteroids Corticosteroids Chorioretinitis (potential cross-reactivity)
• Use with caution:
  • Severe hepatic or renal impairment
  • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Recent acute MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction → risk of myocardial rupture
  • Uncontrolled hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus

Drug interactions

• ↑ Risk of hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia:
  • Diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication
  • Digoxin Digoxin A cardiotonic glycoside obtained mainly from digitalis lanata; it consists of three sugars and the aglycone digoxigenin. Digoxin has positive inotropic and negative chronotropic activity. It is used to control ventricular rate in atrial fibrillation and in the management of congestive heart failure with atrial fibrillation. Its use in congestive heart failure and sinus rhythm is less certain. The margin between toxic and therapeutic doses is small. Cardiac Glycosides
  • Amphotericin B Amphotericin B Macrolide antifungal antibiotic produced by streptomyces nodosus obtained from soil of the orinoco river region of venezuela. Polyenes
• ↑ Risk of ulcers and GI bleeding: NSAIDs NSAIDS Primary vs Secondary Headaches
• ↑ Fluid retention:
  • Androgens Androgens Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens and Antiandrogens
• ↓ Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of fludrocortisone:
  • Proton pump Pump ACES and RUSH: Resuscitation Ultrasound Protocols inhibitors
  • Antacids
  • Bile acid sequestrants Bile Acid Sequestrants Antidiarrheal Drugs
• Dosing adjustment may be necessary for antidiabetic agents.