The panel members appointed to the Eighth Joint National Committee on the Detection, Prevention, and Treatment of High Blood Pressure (JNC 8 expert panel) state that evidence-based dosing information (i.e., dosages shown in randomized controlled trials to reduce complications of hypertension) should be used when available to determine target dosages of antihypertensive agents. Based on such information, an initial adult chlorthalidone dosage of 12.5 mg once daily and a target dosage of 12.5-25 mg once daily are recommended. Other experts have recommended an initial adult chlorthalidone dosage of 12.5-25 mg daily and a usual maximum dosage of 25 mg daily. Dosages of chlorthalidone exceeding 100 mg daily usually do not increase efficacy. Target dosages of antihypertensive agents generally can be achieved within 2-4 weeks, but it may take up to several months. Antihypertensive therapy should be titrated until goal blood pressure is achieved.
If an adequate blood pressure response is not achieved with chlorthalidone monotherapy, another antihypertensive agent with demonstrated benefit may be added; if goal blood pressure is still not achieved with the use of 2 antihypertensive agents at optimal dosages, a third drug may be added.
In patients who experience intolerable adverse effects with chlorthalidone, dosage reduction should be considered; if adverse effects worsen or fail to resolve, it may be necessary to discontinue the diuretic and switch to another class of antihypertensive agent.
When tablets with enhanced oral bioavailability of chlorthalidone are used (i.e., Thalitone), the usual initial dosage for the management of hypertension in adults is 15 mg once daily. If response is inadequate after a sufficient trial, dosage can be increased to 30 mg once daily and, if necessary, to 45-50 mg daily. If blood pressure control still is inadequate at the upper dosage, the manufacturer recommends that a second antihypertensive drug be added rather than increasing the dosage of Thalitone further.