Thiazide Diuretics
- JNC8 recommends Thiazides with ACE-I, ARBS, and CCBs
- Thiazide diuretics are inexpensive effective agents for HTN
- Thiazides cause hypokalemia which causes dig toxicity
- Thiazides should be used with caution in patients with gout
- Initially thiazides cause diuresis then it decreases PVR after long term usage
- A patient may develop hyperglycemia after being prescribed a thiazide diuretic
- Thiazide diuretics reduce calcium excretion by the kidneys and stimulate osteoblasts which help build bone
- Should avoid in patients with serious sulfa allergies; Potassium sparing diuretics such as triamterene & amiloride are alternative options for these patients
- Patients with HTN & osteoporosis have an extra benefit from thiazides
Uses
- Uncomplicated HTN (1st line)
- Heart Failure
- Edema
- HTN accompanied by osteoporosis
Side Effects
- Hypokalemia
- Hyperuricemia
- Hypotension
- Hypercalcemia
- Electrolyte imbalance
- Volume Depletion
- Hypergylcemia
- Hyperlipidemia
THIAZIDE DIURETICS
| Drug Name | Hydrochlorothiazide Chlorthalidone Indapamide Esldrix Metolazone | -Assess for allergy to sulfa drugs -Most common class of diuretics used -Do not use in patients with gout |
|---|---|---|
| MOA | -↓ BP by ↓ blood volume -Acts mainly in the distal tubule to ↓ the reabsorbtion on NA+ ; inhibit reabsorption of Na+ and Cl- in the distal convoluted tubule | ↓ SERUM Na+ concentration (hypernatremia) |
| Effects of Drug | -↑ Excretion of Na+ & Cl- (Hyperosmolar urine) -↑LOSS OF K+ due to the increase in Na+ in the filtrate arriving at the detail tubule -↑ in exchange of K+ for Na+ (can result in hypokalemia) -↑ loss of Mg+ can occur in elderly | -↓Urinary calcium excretion (↓Ca+ content of urine by promoting reabsorption of Ca+) -Reduced peripheal vascular resistance -↓in BP results from a ↓ in blood volume = ↓CO -↑Lipid levels -↓Urate Excretion |
| Therapeutic Effects | -HTN -Heart Failure -Hypercalciuria -Diabetes Insipidus | -DOC for mild HTN & in elderly patients -Combine with another drug for severe HTN |
| Side Effects | -Idiosyncratic rxn (rash, photosensentivity, purpura) -↑plasma renin -Hyponatremia -Hypokalemia | -Hypomagnesaemia -Hyperuricemia (gout) -Hyperglycemia -Hypercalcemia (esp. hyperparathryroid pt) -hypercholesterolemia |
References
Edmunds, M. W., & Mayhew, M. S. (2014). Pharmacology for the primary care provider (4th ed.). St. Louis, MO: Elsevier Mosby.
Harvey, R. A., Clark, M. A., Finkel, R., Rey, J. A., & Whalen, K. (2012). Pharmacology (5th ed.). Baltimore, MD: Lippincott.
JNC8 Guidlines 2014. (2014). JNC 8 Guidlines. Retreived from:
http://jama.jamanetwork.com/article.aspx.articleid=1791497