Antihypertensive effects of metolazone (Zaroxolyn)

B. J. Materson, J. R. Oster, E. C. Perez Stable

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3 Scopus citations


Metolazone, a quinazolinone diuretic, has a renal site of action similar to that of the benzothiadiazines. To evaluate the efficacy and safety of metolazone in the long term treatment of hypertension, 19 patients with idiopathic hypertension were studied. Placebo was given single blind to 2 groups of patients from week 1 to 4 followed by metolazone daily from week 5 to 24. Group I (N = 11; mean age = 52; mean dose metolazone = 3.0 mg.) was given no other hypotensive drug. Group II (N = 8; mean age = 51; mean dose metolazone = 2.6 mg.) received additional non diuretic hypotensive drugs (methyldopa or guanethidine) throughout both control (C) and experimental (E) periods. Patients were evaluated weekly during (C) and monthly during (E) period. Control BP was the last 2 wk of placebo; (E) BP was the average of the last 2 mth of metolazone. In Group I, blood pressure fell from 153 ± 5 (SE) to 136 ± 3 mm. Hg systolic and from 105 ± 2 to 91 ± 2 diastolic. In Group II, blood pressure fell from 164 ± 3 to 137 ± 3 systolic and from 102 ± 3 to 87 ± 2 mm. Hg diastolic (P< 0.001 for both groups). The fall in blood pressure in Group I did not differ significantly from that of Group II. Mean serum potassium (C) was 4.3 and the mean minimal value (E) 3.4 mEq./l. Potassium chloride was given to 8 subjects. After metolazone serum chloride was lower and bicarbonate and urate higher, but there were no relevant clinical symptoms. No adverse eye changes occurred. Metolazone is an effective and safe antihypertensive drug in man. Its metabolic side effects appear to be similar to the benzothiadiazines.

Original languageEnglish (US)
Pages (from-to)890-896
Number of pages7
JournalCurrent Therapeutic Research - Clinical and Experimental
Issue number9
StatePublished - Dec 1 1974

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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