Diuretic Drugs.

What is diuretics?
Diuretics are drugs that promote the excretion of Sodium (Na+) and water in urine.

It is commonly used in patients with;
a) Hypertension (by reducing blood volume)
b) Edema (by concentrating the blood, thus increases plasma oncotic pressure)

They can be classified by their efficacy;
a) High efficacy (Inhibitors of Na+ K+ 2Cl- co-transport)
-Sulphamoyl derivatives: Furosemide, Bumetanide, Torasemide
b) Medium efficacy (Inhibitors of Na+ Cl- symport)
- Benzothiazidines : Hydrochlorothiazide, Benzthiazide, Hydroflumethiazide, Clopamide
- Thiazide-like : Chlorthalidone, Metolazone, Xipamide, Indapamide
c) Weak or adjunctive diuretics
- Carbonic anhydrase inhibitor : Acetazolamide
- Potassium sparing
~Aldosterone antagonist : Spironolactone
~Inhibitors of renal epithelial Na+ channels : Amiloride, Triamterene
- Osmotic diuretics : Mannitol, Isosorbide, Glycerol

Uses of high ceiling diuretics;
1) Edema
- most preferred drug in congestive cardiac failure
2) Acute pulmonary edema
- Furosemide i.v. gives prompt relief
3) Cerebral edema
- Furosemide with osmotic diuretics have high efficacy
4) Hypertension
- given with the presents of renal insufficiency and congestive cardiac failure
5) Blood transfusion
- to prevent vascular overload
6) Hypercalcemia
- Furosemide promotes calcium excretion through the kidney

Uses of thiazides;
1) Edema
- good in maintenance therapy
2) Hypertension
- preferably better than Furosemide
3) Diabetes insipidus
- Reduces urine volume (unlike Furosemide)
4) Hypercalciuria
- Reduces calcium excretion (unlike Furosemide)

Adverse effects
1) Hypokalemia : excess potassium loss via urine
2) Acute saline depletion : Overdosage (esp. Furosemide) may cause dehydration and fall in blood pressure
3) Dilutional hyponatremia
4) GIT and CNS disturbances : Nausea, vomiting, diarrhoea
5) Hearing loss : rarely, but increases risk in renal insufficiency