Pharmacology of diuretics used to treat hypertension

	Bioavailability (%)	Half-life (hours)	Duration of action (hours)
Thiazide diuretics*
Bendroflumethiazide	90	3 to 4	6 to 12
Chlorothiazide	9 to 56 (dose dependent)	Biphasic: Initially 1 to 2, then ~12	6 to 12
Hydrochlorothiazide	65 to 75	Biphasic: Initially ~5, then 6 to 15	6 to 12
Thiazide-like diuretics
Chlorthalidone	65	40 to 60^¶	24 to 72
Indapamide	90	Biphasic: Initially ~14, then 25	16 to 36
Metolazone	65	6 to 20	18 to 25
Loop diuretics
Bumetanide	80 to 90	1 to 1.5	4 to 6
Furosemide	47 to 64 (oral absorption is reportedly more variable in organ dysfunction and with gut-wall edema)	0.5 to 2	6 to 8
Torsemide	80	3.5	6 to 8
Ethacrynic acid	~100	2 to 4	12
Potassium-sparing diuretics
Amiloride	15 to 25 (variable)	Biphasic: Initially 6 to 9, then ~20	24
Triamterene	50	2 to 4	7 to 9
Aldosterone antagonists, potassium sparing
Eplerenone	69	4 to 6	Insufficient data
Spironolactone	65	1.5 (15)^Δ	48 to 72

Data shown are for oral administration in patients with normal kidney and cardiac function.

* Maximal antihypertensive effect is seen with low doses after several weeks of use.

¶ Prolonged serum half-life of chlorthalidone does not fully predict the duration of clinical effect.

Δ The half-life of one active metabolite, canrenone, is 15 hours.

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