indication

For management of hypertension either as the sole therapeutic agent or to enhance the effect of other antihypertensive drugs in the more severe forms of hypertension.

pharmacology

Chlorthalidone, a monosulfonamyl diuretic, differs form other thiazide diuretics in that a double ring system is incorporated into its structure. Chlorthalidone is used alone or with atenolol in the management of hypertension and edema.

mechanism of action

Chlorthalidone inhibits sodium ion transport across the renal tubular epithelium in the cortical diluting segment of the ascending limb of the loop of Henle. By increasing the delivery of sodium to the distal renal tubule, Chlorthalidone indirectly increases potassium excretion via the sodium-potassium exchange mechanism.

toxicity

Symptoms of overdose include nausea, weakness, dizziness and disturbances of electrolyte balance.

biotransformation

Liver

absorption

Absorbed relatively rapidly after oral administration.

half life

40 hours

route of elimination

The major portion of the drug is excreted unchanged by the kidneys.

drug interactions

Deslanoside: Possible electrolyte variations and arrhythmias

Diazoxide: Significant hyperglycemic effect

Digitoxin: Possible electrolyte variations and arrhythmias

Digoxin: Possible electrolyte variations and arrhythmias

Dofetilide: Increased risk of cardiotoxicity and arrythmias

Lithium: The thiazide diuretic, chlorthalidone, may increase serum levels of lithium.

Tenoxicam: Tenoxicam may antagonize the blood pressure lowering effect of Chlorthalidone. Monitor for changes in the therapeutic effect of Chlorthalidone if Tenoxicam is initiated, discontinued or dose changed.

Trandolapril: The thiazide diuretic, Chlorthalidone, may increase the hypotensive effect of Trandolapril. Chlorthalidone may also increase the nephrotoxicity of Trandolapril. Monitor for postural hypotension at initiation of concomitant therapy and renal dysfunction during chronic therapy.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.