Pharm study guide

Topics: Antipsychotic, Acetylcholine, Dopamine Pages: 65 (10801 words) Published: April 15, 2014
Unit 5 Notes
Chapter 41 Diuretics
Drugs that increase urinary output
Two major applications
Treatment of hypertension
Mobilization of edematous fluid to prevent renal failure
Introduction to Diuretics Figure 41-1
How diuretics work – mechanism of action
Blockade of sodium and chloride reabsorption
Site of action
Proximal tubule produces greatest diuresis
Adverse effects
Hypovolemia
Acid-base imbalance
Electrolyte imbalances
Figure 41-2
Classification of diuretics
Four major categories
High-ceiling (loop) – furosemide
Thiazide – hydrochlorothiazide
Osmotic – mannitol
Potassium-sparing: two subdivisions
Aldosterone antagonists (spironolactone)
Nonaldosterone antagonists (triamterene)
Fifth group
Carbonic anhydrase inhibitors
High-Ceiling (Loop) Diuretics
Furosemide (Lasix)
– most frequently prescribed loop diuretic
Mechanism of action
Acts on ascending loop of Henle to block reabsorption
Pharmacokinetics
Rapid onset (oral 60 min; IV 5 min)
Therapeutic uses
Pulmonary edema
Edematous states
Hypertension
Adverse effects
Hypokalemia
Hyponatremia, hypochloremia, and dehydration
Hyperglycemia & Hyperuricemia
Hypotension
Loss of volume
Relaxation of venous smooth muscle
Ototoxicity
Drug interactions
Digoxin
May cause imbalance in digoxin levels due to fluctuation in potassium levels Ototoxic drugs
May cause tinnitus
Potassium-sparing diuretics
May help to prevent hypokalmia
Lithium
By lowering sodium levels can cause lithium accumulation and raise it to a toxic level Antihypertensive agents
May reduce blood pressure to critical level
Nonsteroidal anti-inflammatory drugs
NSAIDs can blunt the diuretic effect of Lasix
Potassium wasting
May increase hypokalemia
Preparations, dosage, and administration
Oral
Parenteral
Thiazides and Related Diuretics
Hydrochlorothiazide
Also known as benzothiadiazides
Effects similar to those of loop diuretics
Increase renal excretion of sodium, chloride, potassium, and water Maximum diuresis is considerably lower than that produced by loop diuretics Not effective when urine flow is scant (unlike loop diuretics) Action – early segment distal convoluted tubule

Peaks 4-6 hours
Therapeutic uses
Essential hypertension
Edema
Diabetes insipidus
Adverse effects
Hypokalemia
Hyponatremia, hypochloremia, and dehydration
Use in pregnancy and lactation
Enters breast milk
Hyperglycemia
Hyperuricemia
Drug interactions
Digoxin
May cause fluctuations in the potassium level
Augments effects of hypertensive medications
Can reduce renal excretion of lithium (leading to accumulation)
Because of sodium fluctuations
NSAIDs may blunt diuretic effect
Can be combined with ototoxic agents without increased risk of hearing loss Potassium-Sparing Diuretics
Aldosterone Antagonist (Spironolactone)
Useful responses
Modest increase in urine production
Substantial decrease in potassium excretion
Rarely used alone for therapy
Aldosterone antagonist
Spironolactone
Nonaldosterone antagonists
Triamterene
Spironolactone (Aldactone)
Mechanism of action
Blocks aldosterone in the distal nephron
Retention of potassium
Increased excretion of sodium
Therapeutic uses
Hypertension
Edematous states
Heart failure (decrease mortality in severe failure)
Less common uses
Primary hyperaldosteronism
Premenstrual syndrome
Polycystic ovary syndrome
Acne in young women
Endocrine effects- spironolactone is a steroid derivative with a structure similar to that of steroid hormones (Progesterone, estradiol, & Testosterone) Adverse effects
Hyperkalemia
Benign and malignant tumors
Endocrine effects
Drug interactions
Thiazide and loop diuretics
Agents that raise potassium levels

Osmotic Diuretic
Mannitol (Osmitrol)
Promotes diuresis by creating osmotic force within lumen of the nephron Pharmacokinetics
Drug must be given parenterally
Therapeutic uses
Prophylaxis of renal failure
Reduction of intracranial pressure
Reduction of...
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