Diuretic Drugs
Diuretic DrugsP. Sutton, MS, RNNursing 2 DHSONPharmacology
Chapter 26DiureticsDrugs that accelerate urine formationRemove
sodium and water from the bodyMost commonly prescribed
drugsHypotensive activityExert effect on nephronGFR used to adjust
dosesAdvantagesRelatively low in costFavorable safety
profileProblems Metabolic adverse effects that result from
excessive fluid and electrolyte lossEffects are usually dose
related and controlled with dose titration/adjustmentSee Table 26-1
pg 405LOOP DIURETICSPotent diureticsChemically related to
sulfonamide antibioticsContraindicated in sulfa allergic
patientsCommonly given to patients with sulfa allergiesNurse to be
aware of potential for allergic reactions
Mechanism of ActionRenal, cardiovascular and metabolic
effectsAct on loop of HenleBlock chloride and sodium
resorptionBelieved to activate renal prostaglandinsBeneficial
hemodynamic effectsUseful when rapid diuresis is neededOften single
dose is effectiveMajor adverse effects: electrolyte
imbalanceIndicationsManage edema associated with heart failure and
hepatic or renal diseaseControl hypertensionIncrease renal
excretion of calciumHeart failure resulting from diastolic
dysfunctionContraindicationsDrug allergy Also consider drug allergy
to sulfanamidesHepatic comaSevere electrolyte lossAdverse
EffectsCNS dizziness, headache, tinnitus, blurred visionGI Nausea,
vomiting, diarrheaHematologic agranulocytosis, thrombocytopenia,
neutropeniaMetabolic hypokalemia, hyperglycemia, hyperuricemiaDrug
Interactions- See Table 26-3 pg 407Currently Available Loop
DiureticsBumetanide 1mgEthacrynic Acid 50mgFurosemide 40mgTorsemide
10mgFurosemide (Lasix)Most commonly used loop diureticHas all
therapeutic effects of loop diureticsUsed to managePulmonary
edemaLiver diseaseEdema assoc with heart failureAscitesNephrotic
syndromeHTNOnset: IV 5minPO 30-60minPeak: IV 15minPO 1-2 hrHalf
LifeIV 1-2 hrPO 1-2 hrDurationIV 2hrPO 6-8 hrsPOTASSIUM SPARING
DIURETICSReferred to as aldosterone inhibiting
diureticsSpironolactone is competitive antagonist of
aldosteroneCause sodium and water to be excreted while retaining
potassiumCurrently Available Drugs in the ClassAmilorid
(Midamor)
Spironolactone (Aldactone)
Triamterene (Dyrenium)
Mechanism of ActionWork in collecting ducts and distal
convoluted tubulesInterfere with sodium-potassium
exchangeSpironolactone binds to aldosterone receptorsAmiloride and
triamterene do not bind to aldosterone receptors, but inhibit
aldosterone induced and basal sodium reabsorptionOften prescribed
for children with heart failureCompete with thiazides and loop
diureticsGenerally used as adjuncts to thiazide
treatmentIndications Applications vary depending on the
drugSpironolactone and Triamterene used to treat hyperaldosteranism
and HTNSpironolactone and cardioprotective benefitsAmiloride less
effective for long term useAmilrode useful in metabolic alkalosis
and primarily used to treat heart failureAdverse EffectsSignificant
effects are specific to individual
drugsSpironolactoneGynecomastiaAmenorrheaIrregular
mensesPostmenapausal bleedingTriamterene Reduces folic acid levels
and causes renal calculi and urinary castsPrecipitates megoblastic
anemia (rare)
Hyperkalemia can result when Potassium Sparing Diuretics are
used in combination with each other and/or other Potassium Sparing
drugs (ie ACEIs)Interactions Concurrent use of potassium sparing
diuretics and lithiumACEIsPotassium SupplementsNSAIDSAmiloride
(Midamor)Used in combination with loop or thiazide diuretics to
treat heart failureHyperkalemia may occur when taken aloneUse in
caution for pts with renal impairement or DM and in the elderlyWeak
antihypertensive propertiesAvailable in oral form onlyAvailable in
comb for w/ hydrochlorothiazide
Onset: 2 hrsPeak 6-10 hrsHalf Life 6-9 hrsDuration 24
hrsSpironolactone Synthetic steroid that blocks aldosterone
receptorsUsed in high doses to treat ascitesHyperkalemia common
complicationFrequent K+ monitoringMost commonly ordered Potassium
Sparing Diuretic for children w/ heart failureAvailable in oral
form only and in comb with hydrochlorothiazideOnset 1-3 daysPeak
2-3 daysHalf life 13-24 hrsDuration 2-3 daysTriamtereneSimilar to
amilorideActs directly on distal renal tubule of nephronDepresses
sodium resorption and excretion of potassium and hydrogenAvailable
in oral form onlyAvailable in combination form with
hydrochlorothiazideOnset 2-3 hrsPeak 6-8 hrsHalf life 2-3
hrsDuration 12-16 hrsTHIAZIDES AND THIAZIDE-LIKE DIURETICSPrimary
site of action is distal confoluted tubuleResult in osmotic water
lossCause direct relaxation of arteriolesBeneficial hemodynamic
effectsEffect diminishes as renal function decreasesMajor adverse
effect from electrolyte imbalMetabolic disturbances:
hyperlipidemia, hyperglycemia and hyperuricemiaIndications Edema of
various originsIdiopathic hypercalcemiaDiabetes
InsipidusHypertensionAdjunct drugs in management of heart failure
and hepatic cirrhosisCan be used alone or in combination with other
drugsContraindications Known drug allergyHepatic coma
(metolazone)AnuriaSevere renal failureAdverse Effects-Major Effects
r/t electrolyte and metabolic distrubances:Reduced K+Elevated
CaElevated LipidsElevated GlucoseElevated Uric AcidOther Less
Common Adverse EffectsGI disturbancesSkin
rashesPhotosensitivityThrombocytopeniaPancreatitis Cholecystitis
Toxicity Overdose leads to electrolyte imbalance from
hypokalemiaAnorexiaNauseaLethargyMuscle weaknessMental
confusionHypotnesion Treatment for Toxicity is Electrolyte
ReplacementInteractions CorticosteroidsDiazoxideDigitalis Oral
hypoglycemicExcessive licorice consumptionHydrochlorothiazide
(HydroDIURIL)Considered the prototypical thiazide diureticCommonly
prescribed and inexpensive drugSafe and effectiveUsed in
combination with other drugsAvailable in oral form onlyCeiling
EffectOnset 2 hrPeak 4-6 hrsHalf life 5-15 hrsDuration 6-12
hrsMetolazone (Zyroxolyn)Thiazide-like diureticMore potent than
thiazide drugsGreater potency most visible in pts with renal
dysfunctionAdvantage: remains effective with low creatinine
clearanceMay be given in combo w/ loop diureticsAvailable in oral
form onlyOnset 1 hrPeak 1-2 hrsHalf life 6-20 hrsDuration 24
hrs
