Hydrochlorothiazide

Question 1

Alternate Name and Cost

Answer 1

HydroDiuril or chlorthalidone, total of 5 in class: 4-50$

Question 2

Drug Class

Answer 2

Pharm: thiazide diuretics
Therapeutic: diuretic, antihypertensive

Question 3

Pharmacodynamics

Answer 3

Block reuptake of Cl and Na from tubular fluid after glomerular filtration; also appears to cause decrease in SVR via unclear mechanism, will lower BP by up to 10-15 mm in many patients, useful as monotherapy or in combiations; HCTZ most commonly used, but perhaps some slight edge to chlorthalidone (duration, efficacy) [proximal DCT]

Question 4

Pharmacokinetics

Answer 4

F~70%, excreted unchanged in urine; short half-life (hours); HCTZ not available in IV formulation; onset 2 hr, peak 5 hr, duration 10 hr

Question 5

Toxicity

Answer 5

Allergy to sulfa antibiotics (?); cause K and Mg depletion; cause Na and Cl depletion, metabolic alkalosis, volume depletion, worsen hyperuricemia

Question 6

Interactions

Answer 6

Additive effects with most other antihypertensives

Question 7

Special Considerations

Answer 7

More side effects in geriatric patients; pregnancy Class D; much less effective in patients with reduced GFR

Question 8

Indications and Dose / Route:

Answer 8

12.5 mg or 25 mg po every morning; little benefit (and more toxicity) when given in higher doses

Question 9

Monitor

Answer 9

BP, weight, edema, K, Mg, BUN, creatinine