Chlorthalidone: A Case Study

A medication that could be used instead of hydrochlorothiazide (HCTZ) is chlorthalidone. Current data and evidence suggests that HCTZ is equal to or secondary to chlorthalidone (Allan, Ivers, & Padwal, 2012). Compared to HCTZ, chlorthalidone has both a longer duration and half-life (Cooney, Milfred-LaForest, & Rahman, 2015). Chlorthalidone has also been found to be more vigorous in lowering blood pressure (Cooney et al., 2015). Chlorthalidone works by inhibiting the sodium-chloride co-transporter found in the luminal membrane of the distal convoluted tubule of the ascending loop of Henle (Cooney et al., 2015). Chlorthalidone potentially causes a stronger inhibition of carbonic anhydrase compared to HCTZ leading to a lower intracellular pH and cell volume (Cooney et al., 2015). The recommended dosage for chlorthalidone is 12.5 to 25 mg, with dosage consideration for the elderly (Cooney et al., 2015). For this patient I would start him on chlorthalidone to help lower his blood pressure. Given that he is an older patient, I would want to start him on 12.5 mg initially to prevent hypotension and other adverse effects.
Since he just had blood work with electrolytes included I would not need another set. I would advise the patient to take his blood pressure daily as well to bring back to