Some specific features of the 24 h blood pressure (BP) pattern are linked to the progressive injury of target tissues and the triggering of cardiac and cerebrovascular events. In particular, many studies show the extent of the nocturnal BP decline relative to the diurnal BP mean (the diurnal/nocturnal ratio, an index of BP dipping) is deterministic of cardiovascular injury and risk. Normalization of the circadian BP pattern is considered to be an important clinical goal of pharmacotherapy because it may slow the advance of renal injury and avert end-stage renal failure. The chronotherapy of hypertension takes into account the epidemiology of the BP pattern, plus potential administration-time determinants of the pharmacokinetics and dynamics of antihypertensive medications, as a means of enhancing beneficial outcomes and/or attenuating or averting adverse effects. Thus, bedtime dosing with nifedipine gastrointestinal therapeutic system (GITS) is more effective than morning dosing, while also reducing significantly secondary effects. The dose-response curve, therapeutic coverage, and efficacy of doxazosin GITS are all markedly dependent on the circadian time of drug administration. Moreover, valsartan administration at bedtime as opposed to upon wakening results in improved diurnal/nocturnal ratio, a significant increase in the percentage of patients with controlled BP after treatment, and significant reductions in urinary albumin excretion and plasma fibrinogen. Chronotherapy provides a means of individualizing treatment of hypertension according to the circadian BP profile of each patient, and constitutes a new option to optimize BP control and reduce risk.
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