Previous studies established that a single daily dose of olmesartan remains effective for the entire 24 h without alteration of the day-night blood pressure (BP) pattern. On the other hand, the administration of valsartan or telmisartan at bedtime, as opposed to upon wakening, improves the sleep-time relative BP decline toward a greater dipper pattern without loss of 24 h efficacy. Yet to be determined is whether this administration-time-dependent efficacy is a class-related feature, characteristic of all angiotensin-receptor-blocker (ARB) medications. We studied 123 grade 1 and 2 hypertensive patients, 46.6+/-12.3 yrs of age, randomly assigned to receive olmesartan (20 mg/day) as a monotherapy either upon awakening or at bedtime for three months. BP was measured by ambulatory monitoring for 48 consecutive hours before and after treatment. The 24 h BP reduction was similar for both treatment times. Administration of olmesartan at bedtime, however, was significantly more efficient than morning administration in reducing the nocturnal BP mean. The sleep-time relative BP decline was slightly reduced with olmesartan ingestion upon awakening but significantly increased with ingestion at bedtime, thus reducing the prevalence of non-dipping from baseline by 48%. Olmesartan administration at bedtime, as opposed to in the morning, improved the awake/asleep BP ratio toward a greater dipper pattern without loss of 24 h efficacy. Nocturnal BP regulation was significantly better achieved with bedtime as compared to morning dosing of olmesartan. These effects are comparable to those previously reported for valsartan and telmisartan, thus suggesting that they may be class-related features of ARB medications in spite of differences in their half-life kinetics. These administration-time-dependent effects should be taken into account when prescribing ARB medications for treatment of essential hypertension.
