D I S C U S S I O N
Nebivolol, a third generation beta-blocker, is unique in many properties, and free from many expected side effects of old generation nonselective beta blockers. On the other hand, Atenolol, a second generation selective beta blocker, is one of the reference drugs used in hypertension trials.( 12) Although, lipophilicity is usually accused of central system side effects of beta blockers including negative influences onto sleep, atenolol, a hydrophilic drug, was shown to influence sleep just as negatively as the others.( 13) Hence, this effect might be due to peripheral shielding or some central effects despite low lipophilicity. On the other hand a recent trial comparing beta blockers showed that neither nebivolol nor carvedilol, but bisoprolol decreased nocturnal melatonin release, a feature which might cause sleep disturbances.( 14) It was also shown that only carvedilol slightly decreased quality of life, whereas nebivolol and bisoprolol did not influence quality of life in the study. The authors concluded that different beta-blockers may exert clinically relevant different effects.
In our study, comparing the frequently used second generation drug with the new generation, it was shown that both drugs were effective in terms of normalizing blood pressure in relatively younger patients with mild hypertension. On the other hand, despite relatively higher total PSQI score at the baseline, Nebivolol therapy improved significantly the total PSQI score after the follow up, whereas, Atenolol slightly, but significantly, worsened it compared to basal score. Hence, though, both were equal in terms of ratio of poor sleepers according to PSQI, at the end of follow up, there were more poor sleepers in the Atenolol group compared to Nebivolol.
In terms of limitations, it is possible to speculate the relative improvement in PSQI score, associated with Nebivolol might be due to relatively lower systolic blood pressure at the end of follow up. However, there is no study showing superiority of mean systolic blood pressure of 121 mmHg compared to 124 mmHg in a group of young hypertensive patients without end organ damage in terms of negative influences onto sleep. On the other hand, temporal trend indicating the improvement of sleep quality in the Nebivolol group might well be due to simply blood pressure control and lack of central side effect of the drug as shown by the recent study, and, temporal trend of slight relative worsening might be due to peripheral shielding side effect, which overcame relative benefit of decreasing blood pressure in the Atenolol group. This issue remains to be established.
In conclusion, Nebivolol was shown to improve the sleep quality in terms of PSQI scores in relatively young hypertensive patients with mild hypertension; whereas Atenolol did not. We think that this issue might influence the preferences considering the compliance problem.
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