Abstract
The efficacy of a once-daily combination of chlorthalidone 50 mg plus triamterene 50 mg or chlorthalidone 100 mg plus triamterene 100 mg was compared to that of chlorthalidone 50 mg or 100 mg. This double-blind study was carried out in eighty-eight patients over a treatment period of 12 weeks. All patients entered the active medication period of 12 weeks after a placebo run-in period of 3 to 7 days, during which pretibial or maleolar pitting oedema averaging 2 to 4 mm developed. All patients started at the lower doses, i.e. forty-one started on chlorthalidone 50 mg plus triamterene 50 mg and forty-seven started on chlorthalidone 50 mg. The protocol provided for doubling the dose (but not for reducing it thereafter) at any time during the 12-week period when control of oedema was deemed inadequate. Eight of the combination therapy patients and sixteen of those on chlorthalidone required the higher doses. By Week 12, 96% of the chlorthalidone plus triamterene patients and 100% of the chlorthalidone patients had shown a reduction of at least 2 mm in depth of pits, and 92% and 72%, respectively, had complete disappearance of oedema. The decreases in pitting oedema were paralleled by mean weight losses of 2·4 kg and 3·1 kg, respectively, for the combination treatment group and the chlorthalidone group. Average serum potassium levels throughout the 12-week treatment period were 3·70 mEq/L for the patients taking the combination compared to 3·41 mEq/L of those taking chlorthalidone.
Serum potassium levels were significantly (p < 0·05) better maintained in the chlorthalidone plus triamterene group than in the chlorthalidone group. It is concluded that the combination is as effective as chlorthalidone alone in the treatment of patients with oedema, and that the combination has significantly greater potassium-sparing effect than does chlorthalidone at comparable doses.
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