ANTIDIURETIC POSTLAB

Injection volume formula

Urinary excretion formula

Diuretic index formula

Diuretic activity formula

Diuretics

Drugs that promotes elimination of excess water and sodium in the body by increasing urine production.

1. Natriuretic

2. Aquaretic

2 Classification of Diuretics

1. Natriuretic

2. Aquaretic

1. promote sodium excretion

2. promote water excretion

Natriuretics

Act by diminishing sodium reabsorption at different sites in the nephron, thereby increasing urinary sodium and water losses.

Natriuretics

This will reduce the fluid volume in the body, hence, lowers the blood pressure and relieve fluid build up or edema.

1. Carbonic Anhydrase Inhibitors (CAIs)

2. Loop Diuretics

3. Thiazide Diuretics

4. Potassium Sparing Diuretics

Classification of Natriuretics (4)

Carbonic Anhydrase Inhibitors (CAIs)

Blocks carbonic anhydrase inside the proximal convoluted tubule. It inhibits the action of carbonic anhydrase to reduce the reabsorption of bicarbonate and sodium, therefore, increasing its excretion.

1. Acute mountain sickness

2. Open-angle glaucoma

Indication of CAIs (2)

1. Acetazolamide

2. Dorzolamide

3. Brinzolamide

Examples of CAIs (3)

Carbonic Anhydrase Inhibitors (CAIs)

First line agent for Open-angle glaucoma

Acetazolamide

Inhibits carbonic anhydrase located intracellularly.

Acetazolamide

It decreases the production of aqueous humor and reduces intraocular pressure in patients with chronic open-angle glaucoma.

Acetazolamide

Used in the prophylaxis of symptoms of altitude sickness.

1. Potassium depletion

2. Renal stone formation

3. Drowsiness

4. Paresthesia

Adverse effects of Acetazolamide (4)

Dorzolamide

Reduces the production of aqueous humor

1. Ocular irritation

2. Blurred vision

3. Systemic effects (rare)

Adverse effects of Dorzolamide (3)

Brinzolamide

Treat intraocular pressure in patients with open-angle glaucoma or ocular hypertension.

1. Ocular irritation

2. Blurred vision

3. Systemic effects (rare)

Adverse effects of Brinzolamide (3)

Loop Diuretics

Inhibit the co-transport of Na+/K+/2Cl− in the thick ascending limb of the loop of Henle.

Na+/K+/2Cl− cotransporter

Facilitates the transport of sodium, potassium, and chloride ions inside the cell.

1. Anion overdose

2. Edema

Indication for Loop Diuretics (2)

1. Bumetanide

2. Torsemide

3. Furosemide

4. Ethacrynic acid

Example of Loop Diuretics (4)

Bumetanide

This drug is more potent than Furosemide and has a relatively shorter duration of action compared to Torsemide.

Torsemide

This drug has a longer half-life compared to Furosemide and used to treat high blood pressure, especially in patients who have concurrent fluid retention.

Furosemide

This drug prevents the reabsorption of sodium (Na+), potassium (K+), and chloride (Cl−) back into the bloodstream.

Furosemide

Drug of choice for pulmonary edema

Ethacrynic acid

This drug is rarely used but is an alternative in patients who have a hypersensitivity reaction to a typical loop diuretic.

Has a relatively higher risk of causing hearing loss or tinnitus (ototoxicity).

Adverse effect of Ethacrynic acid (1)

Ethacrynic acid

Due to its ototoxicity that can cause permanent hearing impairment, it is only used if the px is allergic to loop diuretics.

1. Allergic reactions (with exception with ethacrynic acid)

2. Electrolyte imbalance

Adverse effects of Loop Diuretics (2)

1. Loop Diuretics

2. Sulfonamide

1. ____ _________ such as furosemide contains sulfonamide group that can cause hypersensitivity reactions

2. Ethacrynic acid does not contain this ___________ group, hence, it does not exhibit allergic reactions.

Thiazide Diuretics

Inhibits Na+/Cl− cotransporter in the distal convoluted tubule.

Na+/Cl− cotransporter

Facilitates the reabsorption of sodium and chloride in the body.

1. Hypertension

2. Idiopathic hypercalciuria

Indication of Thiazides (2)

Thiazides

First line of tx for Hypertension

Idiopathic hypercalciuria

There is a loss of too much calcium in the urine without specific reason.

1. Benzothiadiazides

   • Chlorothiazide

   • Hydrochlorothiazide

2. Thiazide-like

   • Chlorthalidone

   • Indapamide

   • Metolazone

Examples of Thiazides (2)

Chlorothiazide

First orally active thiazide and available in both oral and intravenous forms.

Hydrochlorothiazide

Treatment of peripheral edema related to heart failure.

Chlorthalidone

Approximately twice as potent as hydrochlorothiazide and considered a preferred option for hypertension (has long duration of action).

Metolazone

More potent than thiazides and usually used in combination with other diuretics, such as loop diuretics if there is a severe fluid.

retention and diuretics alone are not

working

1. Aldosterone antagonists: direct antagonism of mineralocorticoid receptors.

2. ENaC Inhibitors: inhibition of Na + influx through ion channels in the luminal membrane.

MOA of Potassium-Sparing Diuretics (2)

1. Hyperaldosteronism

2. Resistant hypertension

3. Heart failure

4. Ascites

Indication of Potassium-Sparing Diuretics (4)

1. Spironolactone

2. Eplerenone

Examples of Aldosterone Antagonists (2)

1. Spirinolactone

2. Eplerenone

1. Direct antagonist of aldosterone; prevents salt retention.

2. Competitive antagonist of aldosterone at mineralocorticoid receptors.

1. Hyperkalemia

2. Gynecomastia (spironolactone, not eplerenone)

Adverse effects of Aldosterone Antagonists (2)

1. Amiloride

2. Triamterene

Examples of ENaC Inhibitors (2)

1. Amiloride

2. Triamterene

1. Blocks epithelial sodium channels in collecting tubules.

2. Also blocks epithelial sodium channels in collecting tubules, much less potent, more toxic.

1. Spirinolactone and Eplerenone

2. Amiloride and Triamterene

Uses

1. CHF; HTN Aldosteronism

2. Reduces lithium-induced polyuria

Hyperkalemic metabolic acidosis

Adverse effect of ENaC Inhibitors (1)

Osmotic Diuretics

Physical osmotic effect on tissue water distribution because it is retained in the vascular compartment.

1. Increased intracranial pressure

2. Glaucoma

Indication of Osmotic Diuretics (2)

Intravenously

Mannitol is given

1. Hyponatremia

2. Dehydration

3. Hyperkalemia

4. Hypernatremia

Adverse effects of Mannitol (4)

ADH Agonist

Selective vasopressin V2 receptor agonist.

1. Pituitary diabetes insipidus

2. V2 receptor

1. Indication of ADH Agonist

2. Receptor that is responsible for water reabsorption.

1. Vasopressin

2. Desmopressin

Examples of ADH Agonist (2)

1. Vasopressin

2. Desmopressin

3. Hyponatremia and GI Disturbances

ADH AGONIST

1. Used for pediatric primary hyponatremia; GI Disturbances enuresis • hemophilia A and von Willebrand disease. It can also be used for coagulation disorders.

2. Sometimes used to control bleeding from esophageal varices.

3. ADE of ADH Agonist (2)

ADH Antagonist

V1a and/or V2 receptor antagonist.

1. Hyponatremia

2. Heart failure

Indication of ADH Antagonist (2)

1. Tolvaptan

2. Conivaptan

Examples of ADH Antagonist (2)

1. Conivaptan

2. Tolvaptan

3. Infusion site reactions

1. Antagonist of V1a and V2 receptor

2. Selective V2 receptor antagonist

3. ADE of ADH Antagonist

Hydrochlorothiazide

Directly inhibits the sodium chloride cotransporter located on the apical membrane of the distal convoluted tubules in the kidney.

1. Abacavir - Hydrochlorothiazide may slow down the body’s process of eliminating abacavir, an antiviral medication. This can lead to higher levels of abacavir in the blood, which may increase the risk of side effects.

2. Acebutolol - When used together with acebutolol, a beta-blocker, hydrochlorothiazide may increase the effectiveness of acebutolol, potentially enhancing blood pressure reduction.

Hydrochlorothiazide Possible Drug Interactions (2)

Spirinolactone

Works by increasing the excretion of sodium and water while retaining potassium. This dual effect makes it useful as both a diuretic (helping to remove excess fluid) and an antihypertensive (helping to lower blood pressure).

1. Salbutamol: When used with Spironolactone, Salbutamol’s effectiveness may decrease, potentially reducing its therapeutic impact.

2. Acetaminophen: Spironolactone may cause Acetaminophen to be excreted more quickly, lowering its levels in the blood and possibly reducing its effectiveness.

Spirinolactone Possible Drug Interactions (2)

Furosemide

Promotes the excretion of sodium and water by blocking their reabsorption in the kidney’s proximal and distal tubules, as well as the loop of Henle. This results in a strong diuretic effect, helping to reduce fluid buildup and lower blood pressure.

1. Acebutolol: Furosemide may enhance the blood pressure-lowering effects of Acebutolol, which can increase its effectiveness as an antihypertensive.

2. Abaloparatide: Using Furosemide with Abaloparatide can raise the risk or severity of side effects.

Furosemide Possible Drug Interactions (2)