Makindo Medical Notes

Related Subjects: |Hypertension |Acute Heart Failure |Chronic Heart FailureLoop Diuretics | Entresto Sacubitril with Valsartan | Ivabradine | Furosemide | Angiotensin Converting Enzyme Inhibitors | Cardiac Resynchronisation Therapy (CRT) Pacemaker |

Its diuretic effect is dose dependent. In cases of chronic renal failure, very high doses may be required. Diuretics should not be used on a long-term basis to treat simple gravitational oedema. This will usually respond to increased ambulation, raising the legs and support stockings.

About: Always check the BNF link here

• Loop diuretics: See BNF or equivalent for UpToDate prescribing advice
• These are potent diuretics useful for the rapid excretion of Salt, other electrolytes and water. Often used in the acute treatment of Left ventricular failure.

Chemistry

• It is an anthranilic acid derivative: 4-chloro-N-furfuryl-5-sulfamoylanthranilic acid

Mode of action

• Block primarily the absorption of sodium and chloride not only in the proximal and distal tubules but also in the loop of Henle. Heavily bound to albumin.
• Effect depends on renal clearance so may be diminished in older patients

Indications/Dose

• Fluid overload (CCF/LVF. Central oedema):Furosemide (US Lasix) 20 mg OD to 80 mg BD.
• Mild Peripheral Oedema: Furosemide (US Lasix) 20-40 mg OD but may settle with leg elevation and low doses on alternate days. Watch for orthostatic hypotension. Combine with increased ambulation, raising the legs and support stockings.
• Acute LVF:Furosemide (US Lasix) 50-100 mg given as a single iv dose or an infusion over several hours
• Hypertension: Often given with An ACEI or ARB:Furosemide (US Lasix) 20-40 mg OD

Dose range:You must check with BNF or drug datasheet

Contraindications

• Avoid with ototoxic drugs
• Monitor renal function and electrolytes
• Hypokalaemia can increase Digoxin toxicity

Side effects

• Elderly patients are particularly susceptible to the side-effects of diuretics.
• Volume depletion and orthostatic hypotension and falls especially in elderly
• Low K, Low Mg, Low Ca Raised Ca in urine, Raised uric acid (gout), Raised Glucose
• Low BP, gynecomastia, urinary retention, AKI
• Ototoxicity - tinnitus especially avoid with aminoglycosides

Interactions

• Digoxin toxicity as causes hypokalaemia
• Can cause lithium toxicity through its actions on renal clearance