Does a diuretic cause a further fall in blood pressure in hypertensive patients already on nifedipine?

The effect of the addition of a diuretic, bendrofluazide, for 1 month was studied in 12 hypertensive patients who were already on treatment with nifedipine tablets (20 mg b.i.d.) When nifedipine was maximally effective, that is, at 2 hours after the last dose, the diuretic had no further blood-pressure-lowering effect. These results suggest that unlike most other blood-pressure-lowering agents, there is little point in giving a diuretic to patients who are already on nifedipine, and if blood pressure is not controlled on nifedipine alone, it may be more effective to add either a beta blocker or a converting enzyme inhibitor. This has the advantage of avoiding the metabolic problems of diuretics.