A comparison of antihypertensive effects between two formulations of atenolol: tenolol and tenormin.

BACKGROUND

Atenolol is a cardioselective beta-blocker. Tenolol is a new formulation of atenolol, with bioequivalence to the original atenolol (Tenormin). This study was designed to compare the antihypertensive effects between the two formulations of atenolol, Tenolol and Tenormin.

METHODS

Twenty-three patients, with mild to moderate hypertension untreated with any antihypertensive drugs, were recruited. They were randomized to receive two weeks of placebo, four weeks of Tenolol or Tenormin (100 mg once daily) and two weeks of placebo. Then the treatments were crossed over for four more weeks.

RESULTS

At two weeks five patients were excluded because their blood pressures (BP) were below 160/90 mmHg. The baseline BPs for the patients receiving Tenormin (162 +/- 18/97 +/- 8 mmHg) and Tenolol (164 +/- 17/97 +/- 9 mmHg) were not distinct. After two weeks of treatment with Tenormin or Tenolol, systolic BPs decreased by 12 +/- 11 mmHg and 13 +/- 14 mmHg, respectively (p < 0.01 for both formulations). Similarly the diastolic BPs decreased significantly (p < 0.01) by 7 +/- 9 mmHg and 7 +/- 10 mmHg, respectively. The hypotensive effects persisted at four weeks of treatment for both formulations. Reductions in systolic and diastolic BPs by treatment with Tenormin and Tenolol were not significantly different by two-way ANOVA analysis. There were no side effects in any patient throughout the study.

CONCLUSIONS

The results indicate that the generic formulation of atenolol (Tenolol) has comparable antihypertensive effects as the original formulation (Tenormin).