WEEK 5- Diuretics

Question 1

Diuretic Agents

Answer 1

Drugs that increase the rate of urine formation
Result: removal of sodium and water (where water goes, sodium follows)

hypokalemic

Question 2

Mechanism of Action

Answer 2

Cause dilation of the arteries

Therefore decrease peripheral vascular resistance

They decrease extracellular fluid through increased urination

Decrease fluid volume and plasma

Therefore decreasing cardiac workload (therefore the heart doesn’t have to work so hard)

Question 3

Diuretic Agents-CATEGORIES.

Answer 3

Carbonic anhydrase inhibitors
Loop diuretics
Osmotic diuretics
Potassium-sparing diuretics
Thiazide and thiazide-like diuretics

These agents are classified according to their site of action in the nephron –don’t need to know 1

Their potency is determined by its function in the nephron to inhibit Na+ and water from being reabsorbed

The greater the blockage of absorbing Na+ and water the greater the amount of diuresis therefore the greater the potency

Question 4

Carbonic Anhydrase Inhibitors CAIs: Indications

Answer 4

Not v popular, a lot of side effects
Use as adjunct agents in the long-term management of open-angle glaucoma (they use beta-blockers to treat glaucoma)

To lower intraocular pressure before ocular surgery

Also useful in the treatment of:
Glaucoma
Edema

Eg: acetazolamide (Diamox)

Question 5

CAIs: mechanism

Answer 5

glomerulus in THE proximal tubules where 2/3 of water and sodium is reabsorbed here

CAIs do not allow sodium and water to be reabsorbed into the blood and therefore is eliminated in the urine (blocking action)

Not commonly used due to the potential for severe metabolic acidosis with prolonged use

Question 6

Loop Diuretics

Answer 6

Furosemide (Lasix)

Primarily used for pulmonary edema, heart failure, liver disease, nephrotic syndrome and ascites

**FIRST LINE FOR WHEN - fast diuresis is necessary
Half life 1-2hr, onset 1hr, peak 1-2hr duration 4 to 8hr

If there is a shift of fluid this quick, this effects BP and become hypotensive
The pnt needs to be catherized (IV)

Question 7

Ascites—

Answer 7

accumulation of fluid into the peritoneal area

Question 8

Loop Diuretics: Mechanism of Action

Answer 8

Act directly on the ascending limb of the loop of Henle to inhibit sodium and chloride reabsorption
Increase renal prostaglandins, resulting in the dilation of blood vessels and reduced peripheral vascular resistance

Question 9

Loop Diuretics: Drug Effects

Answer 9

**Potent diuresis and subsequent loss of fluid
Decreased fluid volume causes:
Reduced BP
Reduced pulmonary vascular resistance
Reduced systemic vascular resistance
Reduced central venous pressure
Reduced left ventricular end-diastolic pressure
Potassium depletion

Question 10

Loop Diuretics:Indications

Answer 10

Edema associated with heart failure, hepatic or renal disease
Control of hypertension
Useful when rapid diuresis is needed - effect lasts 2hr
They can still work when the kidney function is diminished
Does not damage the kidney
Single daily dose is usually given in the morning- so they don’t get up all night using the bathroom

Question 11

Major side effect of loops is

Answer 11

electrolyte imbalance—prolonged high doses may cause hearing loss–ototoxicity

Question 12

Loop Diuretics: Side Effects

Answer 12

Dizziness, headache, tinnitus (ringing in the ear) (prolonged high doses may cause hearing loss—ototoxicity), blurred vision, neutropenia, thrombocytopenia, hyperglycemia, hyperuricemia

Question 13

Osmotic Diuretics

Answer 13

Mannitol (Osmitrol)

Used to reduce intracranial pressure and cerebral edema –like brain tumors, infection, head injury, CVA, or if they are on VIT.A (if overdosed can cause intracranial pressure. The pnt would be vomiting if they overdosed)
Elevated intra-ocular pressure

Administer through filter—may crystallize when exposed to low temperatures

Question 14

Osmotic Diuretics: Mechanism of Action

Answer 14

Work in the proximal tubule

Pull water into the blood vessels and nephrons from the surrounding tissues

Inhibits tubular reabsorption of water and solutes increasing urine production

Slight loss of electrolytes especially sodium

Question 15

Osmotic Diuretics: Drug Effects

Answer 15

Reduced cerebral edema

Increased urine production, causing diuresis

Reduced excessive intraocular pressure

Question 16

Osmotic Diuretics: Indications

Answer 16

Used in the treatment of patients in the early, oliguric phase of acute renal failure (ARF)

To promote the excretion of toxic substances

Reduction of intracranial pressure

Treatment of cerebral edema

Treatment of increased intra-ocular pressure

Question 17

Potassium-Sparing Diuretics

Answer 17

Spironolactone (Aldactone)

Amiloride (Midamor)

Question 18

Loop directs, take away potassium and K-sparing diur. leave it AND can cause it to become hyperkalimic

Answer 18

/

Question 19

Potassium-Sparing Diuretics: Indications

Answer 19

Spironolactone

Hypertension
Reversing the potassium loss caused by potassium- losing drugs ie. Loop diuretics

So if they can handle lasix and the K deletion, they got to take this.

Drug drug interaction would not be safe on the fact that it would retain too much fluid

Question 20

Potassium-Sparing Diuretics: Side Effects

Answer 20

Dizziness, headache,Cramps, nausea, vomiting, diarrhea, Urinary frequency, weakness hyperkalemia

Question 21

Thiazide and Thiazide-like Diuretics

Answer 21

** Hydrochlorothiazide (HydroDIURIL)**
Inhibit tubular reabsorption of sodium and chloride ions
Action primarily in the ascending loop of Henle and early distal tubule
Result: water, sodium, and chloride are excreted
Potassium is also excreted to a lesser extent
Dilate the arterioles by direct relaxation

Question 22

Thiazide and Thiazide-like Diuretics: Indications

Answer 22

Hypertension (one of the most prescribed group of agents for this – generally first line drug WITH NO OTHER UNDERLING PROBS because it’s a v safe drug and can change doses easily. They can use this drug for a long time)
Edematous states

Idiopathic hypercalciuria

Diabetes insipidus (lacking hormone ADH and you have to pee all of the time

Adjunct agents in treatment of heart failure (HF), hepatic cirrhosis

Question 23

Thiazide and Thiazide-Like Diuretics: Side Effects

Answer 23

Dizziness, headache, blurred vision, paresthesias, decreased libido
Anorexia, nausea, vomiting, diarrhea

Question 24

Potassium

Answer 24

Potassium is critical for the normal functioning of the muscles, heart, and nerves

It plays an important role in controlling activity of smooth muscles (such as the muscle found in the digestive tract) and skeletal muscles (muscles of the extremities and torso), as well as the muscles of the heart

It is also important for normal transmission of electrical signals throughout the nervous system within the body

Question 25

Hyperkalemia

Answer 25

Hyperkalemia can be asymptomatic, sometimes, patients with hyperkalemia report vague symptoms including:
Nasuea, fatigue, muscle weakness and tingling

Severe hyperkalemia can cause suppression of electrical activity of the heart which includes a slow heartbeat and weak pulse and can cause the heart to stop beating resulting in fatal cardiac standstill

Question 26

Hypokalemia

Answer 26

Potassium affects the way neuromuscular cells discharge energy (depolarize) and then regenerate (repolarize) that energy to be able to fire again. When potassium levels are low, the cells cannot repolarize and are unable to fire repeatedly, so the muscles and nerves can function normally

The effects of low potassium include can cause the following symptoms:
Muscle weakness, muscle aches, muscle cramps, cardiac palpitations

Question 27

Instruct patients to take their medication in the morning to avoid interference with sleep patterns

Answer 27

.

Question 28

normal K range

Answer 28

3.5-5mmol/L

Question 29

Patients taking diuretics along with a digitalis preparation

Answer 29

should be taught to monitor for digitalis toxicity (low potassium levels increase its toxicity) aka digoxin