Diuretics-LOOP Flashcards
What are indications?
Relief of breathlessness in acute pulmonary oedema in conjunction with oxygen and nitrates
Heart failure
Symptomatic fluid of fluid overload in other oedematous states (renal disease, liver failure)
What is the mechanism of action?
Acts on ascending loop of Henle, where they inhibit the Na+ /K+/2Cl- Transporter .
Reduces NaCl reabsorption in ascending loop of Henle
In HF:
cause dilation of capacitance veins .
Reduces cardiac preload and improves contractile function of overstretched heart muscle.
What are important side effects?
Dehydration
Hypotension
As it increases excretion of most electrolytes:
Hypermagnesemia
hypokalaemia
hypocalcaemia
metabolic acidosis
hypochloraemia
Hyponatremia
Hypernatremia
hearing loss
tinnitus
Who are they contraindicated in?
severe hypovolemia
dehydration
In excessive use can worsen gout by inhibiting uric acid secretion
Who should be prescribed with caution?
risk at hepatic encephalapothy
What are common interactions?
Can affect drugs that are excreted by the kidneys.
Lithium: increased levels, reduced excretion
Digoxin: toxicity increased due to hypokalaemia caused by diuretic.
What are dosages for pulmonary oedema?
pulmonary oedema:
furosemide 40mg IV
(IV once daily, IV more rapid and reliable effect)
How should IV doses of furosemide be administered?
Slowly at rate no greater than 4mg/miin
What are ways to monitor efficacy?
Urine output
Body weight (no more than1kg/daily)
What ways can you monitor for safety?
Renal function
electrolytes (esp K+/ Na+)
What is treatment for gravitational oedema?
Diuretic for few days
encourage movement, raising legs, support stockings as longer term alt
Why can bioavailability of furosemide be low in severe fluid overload?
gut wall oedema.
prevented by furosemide IV, but this will not always be possible or desirable.
bumetanide may be a better choice, as there is some evidence that its bioavailability is more predictable.
Bumetanide 1mg is equivalent to about 40mg of furosemide.
