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patho > week 8 pharm > Flashcards

week 8 pharm Flashcards

1
Q

what is a diuretic

A
  • Drugs that accelerate the rate of urine formation
  • Effective treatment of hypertension and heart failure
  • Result: removal of sodium and water
  • Medications that augment “diuresis”
  • Commonly known as “water pills”
  • Used to treat heart failure, liver cirrhosis,
    hypertension and certain kidney diseases
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2
Q

where is most sodium reabsorbed

A
  • 20 to 25% of all sodium is reabsorbed into the bloodstream in the ascending loop of Henle
  • 5 to 10% of sodium reabsorption takes place in the distal convoluted tubules
  • 3% takes place in the collecting ducts
  • If water is not absorbed, it is excreted as urine
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3
Q

MOA of most diuretics

A
  • Most diuretics share the same basic mechanism of action which is the
    blockade of sodium and chloride reabsorption
  • By blocking the reabsorption of these prominent solutes, diuretics
    create osmotic pressure within the nephron that prevents the passive reabsorption of water
  • The increase in urine flow that a diuretic produces is directly related
    to the amount of sodium and chloride reabsorption that it blocks
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4
Q

drugs that act early on the nephron do what

A
  • Drugs that act early in the nephron have the opportunity to block the
    greatest amount of solute (Na+) reabsorption and produce the
    greatest amount of diuresis
  • Cause direct arteriolar dilation, decreasing peripheral vascular
    resistance & reduce:
  • extracellular fluid volume
  • plasma volume
  • cardiac output
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5
Q

severe side effects of diuretics

A
  • Severe potassium deficiencies
  • Electrolyte imbalance
  • Extreme Weakness
  • Fatigue
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6
Q

Loop Diuretics (Furosemide, Lasix):
Mechanism of Action

A

 Act directly on the ascending limb of
the loop of Henle to inhibit chloride and
sodium reabsorption
 Increase kidney prostaglandins,
resulting in the dilation of blood
vessels and reduced peripheral
vascular resistance
- significant amount of diuresis

  • Results in:
  • Reduces blood pressure
  • Reduces pulmonary vascular
    resistance
  • Reduces systemic vascular
    resistance
  • Reduces central venous pressure
  • Reduces LVED pressure
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7
Q

Loop Diuretics:
Indications

A
  • Edema associated with heart failure or hepatic or renal disease
  • Control of hypertension
  • Hypercalcemia (increase renal excretion of calcium)
  • Certain cases of heart failure resulting from diastolic dysfunction
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8
Q

Loop Diuretics:
Contraindications

A
  • Known drug allergy
  • Allergy to sulfonamide antibiotics (caution; crosssensitivity is rare)
  • Hepatic coma
  • Severe electrolyte loss (especially K+ which may require potassium replacement)
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9
Q

loop diuretic advantage over thiazide diuretics

A

Can be given with renal failure
Still work when CrCl falls below 25 ml/min

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10
Q

K needs to be in normal range for which loop diuretic

A

dogoxin

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11
Q

Loop Diuretics: Adverse
Effects

A
  • Central nervous Dizziness, headache, system (CNS) tinnitus, blurred vision
  • Gastrointestinal (GI) Nausea, vomiting, diarrhea
  • Hematological Agranulocytosis, neutropenia, thrombocytopenia
  • Metabolic Hypokalemia,
    hyperglycemia, hyperuricemia
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12
Q

Carbonic Anhydrase
Inhibitors (CAIs) -
Acetazolamide MOA

A
  • Inhibits the enzyme carbonic anhydrase
    found in kidneys, eyes and other areas of
    the body
  • Acts in the proximal tubule
  • Reduces the formation of HCO3 & H+
  • Results in the release of H20 & sodium
    – diuresis
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13
Q

indications of CAIs

A
  • Primarily high-altitude sickness (Sx
    include H/A, nausea, SOB, dizziness,
    drowsiness & fatigue)
  • Glaucoma
  • Edema secondary to heart that has
    become resistant to other drugs
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14
Q

Adverse effects &
interactions of CAI

A
  • Metabolic acidosis
  • Hypokalemia
  • Contraindicated in sever liver or kidney dysfunction
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15
Q

Osmotic Diuretics
[mannitol
(Osmitrol)]:
Mechanism of
Action

A
  • primarily act in the proximal tubule and throughout the nephron.

-They are nonabsorbable, creating an osmotic effect that pulls water into the renal tubules, leading to rapid diuresis.

-They can also shift fluid from intracellular to intravascular spaces.

-These diuretics result in minimal loss of electrolytes, particularly sodium, making them unsuitable for treating peripheral edema.

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16
Q

Osmotic Diuretics:
Indications

A
  • Treatment of patients in the early, oliguric
    phase of acute renal failure
  • To promote the excretion of toxic substances
  • Reduction of intracranial pressure (important)
  • Treatment of cerebral edema (important)
  • Elevated intraocular pressure (glaucoma)
  • administered IV only
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17
Q

Osmotic Diuretics:
Contraindications

A
  • Contraindications:
  • Known drug allergy
  • Severe kidney disease
  • Pulmonary edema (loop diuretics are used
    instead)
  • Active intracranial bleeding (imporant)
18
Q

Osmotic Diuretics:
Adverse effects

A
  • Adverse Effects
  • Convulsions
  • Thrombophlebitis
  • Pulmonary congestion
  • Headaches, chest pains, tachycardia, blurred vision, chills, and fever
19
Q

Potassium-Sparing
Diuretics [spironolactone
(Aldactone)]:
Mechanism of Action

A

-Potassium-sparing diuretics work primarily in the collecting ducts and distal convoluted tubules.

-They interfere with sodium-potassium exchange by competitively binding to aldosterone receptors, which blocks sodium and water resorption normally induced by aldosterone.

-This promotes the excretion of sodium and water while retaining potassium, making them useful for conditions where potassium preservation is desired.

-Low diuresis

20
Q

Potassium-Sparing
Diuretics: Indications

A
  • Hyperaldosteronism
  • Hypertension (generally once 3 drugs haven’t controlled blood pressure)
  • To reverse the potassium loss caused by
    potassium-losing drugs
  • Heart failure (most heart failure guidelines have indications for this drug class) – there are exception
21
Q

Potassium-Sparing
Diuretics: contradictions

A
  • Known drug allergy
  • Hyperkalemia
  • Severe kidney failure or anuria
22
Q

Potassium-Sparing
Diuretics: adverse effects

A
  • Hyperkalemia
  • Gynecomastia (enlarged breasts in men)
  • Amenorrhea
  • Irregular menses
  • Postmenopausal bleeding
  • Sexual dysfunction (?)
23
Q

Potassium-Sparing
Diuretics drug interactions

A
  • lithium
  • angiotensin-converting enzyme (ACE) inhibitors
  • Potassium supplements
24
Q

Thiazide and
Thiazide-Like
Diuretics
hydrochlorothiazide
or indapamide:
Mechanism of
Action

A
  • low diuresis

-Thiazide diuretics inhibit the tubular reabsorption of sodium, chloride, and potassium ions

-primarily acting in the distal convoluted tubule.

-They promote the excretion of water, sodium, and chloride, with some potassium loss.

-Additionally, they cause direct relaxation of arterioles, leading to lowered peripheral vascular resistance and contributing to their antihypertensive effects.

25
Q

Thiazide and Thiazide Like Diuretics indications

A
  • Hypertension (one of the most prescribed group of drugs for this)
  • Edematous states (excess fluid in tissues)
  • Heart failure due to diastolic dysfunction
  • As adjunct drugs in treatment of edema related to heart failure, hepatic cirrhosis, corticosteroid or estrogen therapy
26
Q

Thiazide and Thiazide Like Diuretics:
Contraindications

A
  • Known drug allergy
  • Hepatic coma (metolazone)
  • Anuria
  • Severe kidney failure
27
Q

Thiazide and Thiazide Like Diuretics: Adverse Effects

A
  • Dizziness, headache, blurred vision,
    paranesthesia’s, decreased libido
  • Anorexia, nausea, vomiting,
    diarrhea
  • Genitourinary Impotence (erectile dysfunction)
  • Urticaria, photosensitivity

*Hypokalemia,
hyperglycemia, hyperuricemia

28
Q

Diuretic Drugs:
Nursing Implications

A
  • Monitor serum potassium levels during therapy
  • Potassium supplements are usually not
    recommended when potassium levels exceed 3 mmol/L
  • Signs and symptoms of hypokalemia include muscle weakness, constipation, irregular pulse rate, and overall feeling of lethargy
29
Q

Severe constipation can lead to:

A
  • Fecal impaction
  • Complete obstruction of bowel
30
Q

Psyllium Mucilloid
Bulk-forming (class), and MOA and therapeutic effects

A
  • Trade names
  • Metamucil, Psyllium
  • Therapeutic effects and uses
  • Occasional constipation
  • Reduction of blood cholesterol with longer use
  • Mechanism of action
  • Absorbs water in bowel forming a bulky stool
  • Bulky stool stimulates defecation reflex
31
Q

bulk-forming serious effects

A
  • If not taken with adequate water, can cause obstruction of esophagus or intestines
32
Q

Stimulants MOA and adverse effects

A
  • Increase peristalsis via intestinal nerve stimulation
  • Adverse effects
  • Nutrient malabsorption
  • Skin rashes
  • Gastric irritation
  • Electrolyte imbalances (hypokalemia)
  • Discoloured urine
  • Rectal irritation
33
Q

causes of diarrhea

A
  • GI infection
  • Drugs (antibiotics, NSAIDs, orlistat, digoxin)
  • Inflammation of bowel
  • Foods
  • Diseases of SI and pancreas, leading to malabsorption of food
34
Q

Prolonged diarrhea can cause

A
  • Fluid imbalance
  • pH imbalance
  • Electrolyte imbalance
35
Q

Pharmacotherapy of Diarrhea (3 types)

A
  • Opioids (most effective)
  • decrease GI motility via mu receptors, providing more time for water absorption
  • Codeine
  • Diphenoxylate with atropine (Lomotil)
  • Loperamide (Imodium; available OTC)
  • Non-opioids
  • Bismuth subsalicylate (Pepto-Bismol)
  • draws fluid out of bowel, anti inflammatory
  • Black stool are a common & normal side effect
  • Psyllium – absorbs water to form bulk
36
Q

Prototype Drug Diphenoxylate with Atropine (Lomotil)

A
  • Therapeutic effects and uses
  • Moderate-to-severe diarrhea
  • Mechanism of action
  • Binds mu opioid receptors in GI tract to reduce peristalsis
  • Atropine blocks ACh receptors to reduce peristalsis
  • Combined, this combination provides more time for water to be absorbed
    from lower intestine
  • Adverse Effects
  • Dizziness
  • Lethargy, drowsiness
  • Anticholinergic effects of atropine
37
Q

Complications from chronic vomiting may include

A
  • Dehydration
  • Electrolyte imbalances
  • Significant weight loss
  • Vascular collapse
  • Dehydration
  • Metabolic alkalosis
38
Q

Anticholinergic drugs (ACh blockers)

A
  • Bind to and block acetylcholine (ACh) receptors in the inner ear labyrinth
  • Block transmission of nauseating stimuli to CTZ
  • Also block transmission of nauseating stimuli from the reticular formation to the VC
  • Include scopolamine
  • Also used for motion sickness
39
Q

Antihistamine drugs (H1 receptor
blockers)

A
  • Inhibit ACh by binding to H1 receptors
  • Prevent cholinergic stimulation in vestibular and reticular areas, thus
    preventing nausea and vomiting
  • Include dimenhydrinate (Dinate, Gravol, Nauseatol, others), diphenhydramine (Aller-Aide, Allerdryl, Benadryl), meclizine
    (Bonamine), promethazine (Histantil)
  • Are also used for motion sickness, nonproductive cough, allergy
    symptoms, sedation
40
Q

Serotonin blockers

A
  • Block serotonin receptors in the GI tract, CTZ, and VC
  • Include dolasetron (Anzemet), granisetron (Kytril), ondansetron (Zofran)
  • Are used for nausea and vomiting in patients receiving chemotherapy
    and for postoperative nausea and vomiting
    ** Drug of choice & given prophylactically prior to chemotherapy
    administration of know agent that cause N & V **
41
Q

Tetrahydro cannabinoids

A
  • Are a major psychoactive substance in marijuana
  • Have inhibitory effects on reticular formation, thalamus, cerebral cortex
  • Alter mood and body’s perception of its surroundings
  • Include dronabinol (Marinol), nabilone (Cesamex)
  • Are used for nausea and vomiting associated with chemotherapy and
    anorexia associated with weight loss in patients with acquired immune
    deficiency syndrome (AIDS)

patho (6 decks)

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