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Therapeutics

Compared with atenotol, pindolol decreased bradycardia, tiredness, and cold extremities in hypertension, but increased transient sleep disturbance

ACP J Club. 1991 Jan-Feb;114:18. doi:10.7326/ACPJC-1991-114-1-018


Source Citation

Abrahamsen AM, Digranes 0, Gisholt K. Comparison of the side effects of pindolol and atenolol in the treatment of hypertension. J Intern Med. 1990;228:219-22. [PubMed ID: 2205704]


Abstract

Objective

To compare side effects from 2 antihypertensive agents: a nonselective β-blocker with intrinsic sympathomimetic activity (pindolol) and a selective β-blocker (atenolol).

Design

Randomized, double-blind multicenter trial of 6 months duration.

Setting

63 general practitioners, internists, and medical officers [in Norway], from May 1985 to May 1986.

Patients

349 white outpatients (age range, 20 to 65 years) with mild or moderate hypertension were studied, including untreated and previously unsuccessfully treated patients. 91% completed the trial.

Intervention

Patients were prescribed a fixed daily dose of either pindolol, 15 mg, or atenolol, 100 mg, prepared in identical capsules. If needed, a diuretic was added.

Main outcome measures

Symptoms were recorded before and 1 and 6 months after starting the treatment, and included bradycardia, cold extremities, sleep disturbance, tiredness, bronchoconstriction, depressive mood, impotence, gastrointestinal symptoms, and others that the patient mentioned. Heart rate and blood pressure were recorded.

Main results

Pindolol and atenolol were similarly effective in reducing blood pressure; after 6 months, mean blood pressure decreased from 176/108 mm Hg to 147/92 mm Hg with pindolol, and from 177/108 mm Hg to 150/91 mm Hg with atenolol. 46 patients {26%}* assigned to pindolol and 31 {18%}* patients assigned to atenolol discontinued taking the drugs {P < 0.05}.* Heart rate decreased with both medications, but the percentage of patients with bradycardia (heart rate < 50 beats/min) was higher for atenolol (10%) than for pindolol (no occurrence) after 6 months (P < 0.01). Patients receiving pindolol reported less tiredness (14%) than did patients receiving atenolol (25%) after 6 months (P < 0.02). (Table). Fewer patients receiving pindolol had cold extremities than patients receiving atenolol (P < 0.02) (Table). There was less sleep disturbance in patients receiving atenolol after 1 month (9% compared with 19%: P < 0.02), but after 6 months, rates were similar (12% and 10%) {ARR 2%, CI -6% to 9%, P = 0.6}.* At 6 months dizziness, increased leg fatigue, and gastrointestinal symptoms occurred at similar rates for both medications.

Conclusions

Pindolol and atenolol were equally effective for lowering blood pressure. Patients receiving pindolol for hypertension had less bradycardia, tiredness, and cold extremities.

Source of funding: Sandoz-informasjon.

Address for article reprint: Dr. A. M. Abrahamsen, Department of Internal Medicine, Central Hospital in Rogaland, Stavanger, Norway.

*Numbers calculated from data in article.


Table. Pindolol vs atenolol for treatment of hypertension†

Outcomes at 6 mo Pindolol Atenolol RRR (95%CI) NNT (CI)
Tiredness 14% 25% 42% (6 to 64) 9 (5 to 74)
Cold extremities 18% 34% 46% (18 to 64) 6 (4 to 18)

†Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.


Commentary

This study supports the notion that different types of β-blockers have different risks for adverse effects. In addition, the study suggests that the side-effect profile of pindolol, a nonselective β-blocker with intrinsic sympathomimetic activity, is better than that of atenolol, a selective β1-blocker. However, there are 3 factors that readers should consider before accepting this conclusion. First, patients were required to take a fixed dose of the β-blocker, either pindolol, 15 mg, or atenolol, 100 mg. However, atenolol, 50 mg once daily, is the most frequently prescribed dose in the United States, and by restricting use to the higher dose, adverse effects may have been maximized with only limited additional therapeutic benefit (as is true for thiazide diuretics in treating hypertension).

Second, a similar number of patients in each group had side effects that led to stopping the drug — 24 on pindolol and 21 on atenolol. By this criterion, the drugs had a similar overall risk profile.

Third, a significantly greater number of patients in the pindolol group were excluded from the final 6-month analysis, 22 (13%) receiving pindolol as compared with 10 (6%) receiving atenolol (P = 0.03). 1 possible explanation is that these patients had severe side effects that prompted noncompliance, causing subsequent "loss of blood pressure control," which is 1 of the reasons for exclusion. If this were the case, then the conclusion of the study might have been just the opposite of what was reported.

Arthur T. Evans, MD, MPH
University of North CarolinaChapel Hill, North Carolina, USA