Diuretics Flashcards
Prescription for Hydrochlorothiazide?
25 mg
One tablet daily
Do not Abbreviate
What are the thiazide diuretic agents?
- Hydrochlorothiazide
- Chlorothiazide
Where do the thiazide diuretics work?
o Distal convoluted tubule Sulfonamide molecule • Worry about allergies to sulfur drugs Cells impermeable to water 10% sodium reabsorption • Na+/Cl- transporter sensitive to thiazides •
Indication for Hydrochlorothiazide?
Management of mild-to-moderate hypertension
Treatment of edema in heart failure and nephrotic syndrome
Indication for Chlorothiazide?
Management of hypertension
Adjunctive treatment of edema
Indication for Methyclothiazide?
- Management of hypertension
- Adjunctive therapy of edema
What are the “Ceiling” diuretics for the thiazide diuretics?
Increasing the dose beyond the normal dose does not increase diuretic effect
What are the effects for the thiazide diuretics?
o Increased excretion of sodium and chloride o Loss of potassium o Loss of magnesium o Decreased urinary calcium excretion o Reduced peripheral vascular resistance
What are the kinetics for the thiazide diuretics?
o 1 to 3 weeks to produce a stable reduction in blood pressure lose plasma volume so BP drops
o Then theory is you get direct vasodilation of arterial smooth muscle for long-term control
What are the adverse drug reactions of the thiazide diuretics?
o Hyponatremia (rare) Hypovolemia leading to increase in ADH, diminished diluting capacity of kidney and increased thirst Limit water intake and use lower doses o Hyperuricemia gouty arthritis o Volume depletion Orthostatic hypotension, dizziness o Hypercalcemia o Hypersensitivity Very rare- bone marrow suppression, dermatitis, necrotizing vasculitis, interstitial nephritis o Hyperglycemia Elevated blood glucose levels- harm or hype o Hyperlipidemia Elevated TC, LDL – harm or hype o Hypokalemia How low will I go? o NEED to get BMP on regular basis to check electrolytes (usually not a big deal though) o
What is the main thiazide-like diuretic?
• Chlorthalidone
o Long duration of action
Info about Metolazone?
- More potent than the thiazides
* Causes sodium excretion even in advanced renal failure
Info about Indapamide?
• Low doses- significant antihypertensive effect with minimal diuretic effect
• Gastrointestinal tract excretion- less likely to accumulate in patients with renal failure
•
Prescription for Chlorthalidone?
50 mg
One tablet daily
What was Chlorthalidone noted as ?
Chlorthalidone noted as superior to other agents such as lisinopril, amlodipine or doxazosin
When may the addition of a thiazide to a loop diuretic be helpful?
refractory edema in heart failure, cirrhosis, nephrotic syndrome and renal failure
What are the loop diuretics?
- **Furosemide
- Bumetanide
- Torsemide
Prescription for Furosemide?
40 mg
One tablet twice a day
Where/how do the loop diuretics work?
o Ascending Loop of Henle Sulfonamide molecule Cells impermeable to water 25 to 30% sodium reabsorption • Na+/K+/2Cl- cotransporter
- “High-ceiling diuretics
What are the effects of the loop diuretics?
o Increased excretion of sodium and chloride
o Loss of potassium
o Loss of magnesium
o Increased urinary calcium excretion
o Hypocalcemia avoided as most calcium reabsorbed in distal convoluted tubule
o Reduced renal vascular resistance/ increased renal blood flow
o Result of increased prostaglandin synthesis from loop diuretic use
What is the Diff in IV to PO for furosemide?
~ 50% bioavailability compared to the others, so if 40 mg IV is good, must give 80 mg oral on DC
Indications for furosemide?
Management of edema associated with heart failure and hepatic or renal disease
Acute pulmonary edema
Treatment of hypertension (alone or in combination with other antihypertensives)
Indications for Bumetanide (Bumex™)?
Management of edema secondary to heart failure or hepatic or renal disease (including nephrotic syndrome)
Indications for Torsemide (Demadex™)?
Management of edema associated with heart failure and hepatic or renal disease (including chronic renal failure)
Treatment of hypertension
What is the main use for loop diuretics?
• Main use in treatment of states of volume excess like: o Heart failure o Nephrotic syndrome o Acute and chronic renal insufficiency o Cirrhosis
What is the onset of the loop diuretics?
o Relatively rapid with symptom relief within hours to days
What are the adverse drug reactions of the loop diuretics?
o See thiazides, only electrolyte loss may be more profound Potassium depletion (supplementation) Magnesium depletion (supplementation) o Ototoxicity o ethacrynic acid, aminoglycoside use
What are the Potassium Sparing diuretics? (agents)
- Triamterene, amiloride
- Spironolactone/eplerenone
What are the sodium channel blockers of the Potassium Sparing diuretics?
- Triamterene, amiloride
- 3 to 5% sodium reabsorption at this site
- Used with HCTZ usually
What are the aldosterone antagonists of the Potassium Sparing diuretics?
- Spironolactone/eplerenone
- Blocks stimulation of the Na+/K+ exchange sites - - in collecting tubule (1 to 3% net diuretic effect)
- Sodium lost for diuretic effect but potassium retained
- Spironolactone- hormonal effect
- Works with high levels of aldosterone and vice versa
Indication for amiloride?
Adjunctive treatment with thiazide diuretics or other kaliuretic-diuretic agents in congestive heart failure or hypertension to help restore normal serum potassium levels in patients who develop hypokalemia
Prevent development of hypokalemia in patients who would be exposed to particular risk if hypokalemia were to develop
Indication for Triamterene?
Alone or in combination with other diuretics in treatment of edema and hypertension; decreases potassium excretion caused by kaliuretic diuretics
Indication for Spironolactone?
Management of congestive heart failure
Cirrhosis of the liver accompanied by edema and/or ascites
Nephrotic syndrome
Indication for eplerenone?
- To improve survival of stable patients with left ventricular systolic dysfunction and clinical evidence of congestive heart failure after an acute myocardial infarction
- Treatment of hypertension
o Adverse Drug Reactions for Triamterene and amiloride?
Leg cramps
Increased blood urea nitrogen
Potassium retention
Increased uric acid
Adverse Drug Reactions for Aldosterone antagonists?
Gastric upset (spironolactone)
Gynecomastia (males)
Menstrual irregularities (females)
Potassium sparing diuretics are contraindicated when?
• Generally useful in heart failure
o ACC/AHA guidelines- Class II-IV heart failure
o Contraindicated in baseline serum creatinine above 2.5 mg/dL and serum potassium greater than 5 mEq/L
Prescription for Amiloride?
10 mg
One tablet daily
Prescription for spironolactone?
25 mg
One tablet twice a day
- For HTN
What is the Osmotic Diuretics?
Mannitol
How to write a prescription for Mannitol?
GET INTENSTIVIST INVOLVED!
What is the Intravenous administration for Mannitol?
Inhibits sodium reabsorption in proximal convoluted tubule and Loop of Henle
What is the Inpatient setting for Mannitol?
Reduction of intracranial pressure
Reduction of ocular pressure
MOA for Potassium supplementation?
electrolyte replenishment
ADR for Potassium supplementation?
- asymptomatic hyperkalemia (6.5 to 8 mEq/L; ECG changes
- gastrointestinal symptoms
Note for Potassium supplementation?
watch for patients with renal insufficiency (K+ can rise)
Class drug for Potassium supplementation?
potassium chloride (K-Dur™, Slow-K™)
- IV or oral
- When K+ in low 3’s –> give oral
- When K+ < 3, then give IV!
How many milliequivalents of K+ to bump up serum levels?
20-40 milliequivalents
What are the most common adverse effects of the diuretics?
Fluid and electrolyte abnormalities most common adverse effects:
- 50% of patients receiving a loop diuretic experience potassium levels less than 3.5 mEq/L
- Electrolyte changes occur in first few weeks of therapy and potassium depletion is not progressive with continued treatment
How often do you monitor electrolyte levels in diuretcs?
Other important measures?
- Electrolytes at baseline, in 1 week, in 1 month and periodically
- Volume status assessed at baseline and periodically
- Record weight at home (lose water weight)
Application for HTN?
- Hydrochlorothiazide versus ***chlorthalidone
- As good as ACE inhibitors or calcium channel blockers
Application for Heart Failure?
- Offset to increased plasma volume
- Be careful!
Application for Kidney Disease?
- Address volume retention between dialysis treatments
- Combination therapy
Special Considerations in Geriatrics?
- Fall in GFR diminishes diuretic effect with thiazides
- SHEP trial still showed that isolated systolic -hypertension would respond to low dose chlorthalidone
Special Considerations in Pediatrics?
- Thiazides, spironolactone have been safely used in children
- Avoid furosemide in premature infants with respiratory distress syndrome
- Side effects may not be as apparent or reportable based on patient age
- Watch for changes in personality, eating or sleeping patterns or restlessness and investigate promptly
Summary of Diuretics?
- Diuretics are used to reduce fluid volume, to effect some direct vasorelaxation and thus reduce blood pressure
- Electrolytes can be lost while using diuretics and may need to be replaced.
- In simple cases of hypertension, diuretics are first-line therapy
- Diuretics are a mainstay of heart failure treatment (when volume is a problem)
