Chronopharmacology of angiotensin II-receptor blockers in stroke-prone spontaneously hypertensive rats

Chronopharmacology of high blood pressure—a critical review of clinical evidence

Physiological functions of cardiovascular system (CVS) are exhibiting circadian patterns regulated by complex system of endogenous factors. Preserving this rhythmicity is important for its normal function, whereas disturbing the synchronization with natural day–night cycle can increase the risk of cardiovascular damage. Cardiovascular pathophysiology also follows cyclic variation; time susceptibility and period with maximum risk associated with elevated blood pressure (BP) can be predicted. Given this rhythmic nature, significant changes in efficacy between morning and evening administration of the drug may occur; appropriate timing of pharmacological intervention in therapy of hypertension may affect the efficacy of the treatment.

Chronobiology in nephrology: the influence of circadian rhythms on renal handling of drugs and renal disease treatment

INTRODUCTION

Chronobiology studies the phenomenon of rhythmicity in living organisms. The circadian rhythms are genetically determined and regulated by external synchronizers (the daylight cycle). Several biological processes involved in the pharmacokinetics and pharmacodynamics of drugs are subjected to circadian variations. Chronopharmacology studies how biological rhythms influence pharmacokinetics, pharmacodynamics, and toxicity, and determines whether time-of-day administration modifies the pharmacological characteristics of the drug. Chronotherapy applies chronopharmacological studies to clinical treatments, determining the best biological time for dosing: when the beneficial effects are maximal and the incidence and/or intensity of related side effects and toxicity are minimal. Most water-soluble drugs or drug metabolites are eliminated by urine through the kidney. The rate of drug clearance in the urine depends on several intrinsic variables related to renal function including renal blood flow, glomerular filtration rate, the ability of the kidney to reabsorb or to secrete drugs, urine flow, and urine pH, which influences the degree of urine acidification. Curiously, all these variables present a circadian behavior in different mammalian models.

CONCLUSION

The circadian rhythms have influence in the renal physiology, pathophysiology, and pharmacology, and these data should be taken into account in clinical nephrology practice.

COMPARISON OF INFLUENCE OF VARIOUS REGIMENS OF DRUG INTAKE ON 24 HOUR bLOOD PRESSURE, CENTRAL AORTIC PRESSURE AND VASCULAR WALL STIFFNESS IN SYSTEMIC HYPERTENSION PATIENTS WITH ISCHEMIC STROKE

Aim. To assess and compare the efficacy of combination antihypertension drugs influence with various dosage regimens during 24 hour, on the parameters of daily blood pressure (BP) profile, central aortic pressure (CAP) and vessel wall stiffness in arterial hypertension (AH) patients with ischemic stroke (IS).

Material and methods. To the study, 177 AH patients included, with IS within last 4 weeks. All patients were randomized to 3 groups depending on the regimen of antihypertensive drugs combination intake during 24 hours. At baseline and in 12 months of therapy all patients underwent 24 hour BP monitoring (ABPM), CAP measurement and vessel wall stiffness evaluation.

Results. In 8 weeks of antihypertension therapy, target pressure level achievement was significantly more common in b. i.d. valsartan (group 3) comparing to once daily in the morning (group 1) or evening (group 2) (p<0,05). In all groups there were statistically significant positive changes in ABPM, CAP and stiffness. Also, in the group 2 there was significantly (p<0,05) more prominent decrease of the main ABPM, CAP and stiffness parameters than in the group 1. Valsartan b. i.d. led to significantly more prominent (p<0,05) improvement of the main ABPM, CAP and stiffness parameters improvement comparing to both variants of its once daily regimens. In 12 months of chronopharmacotherapy, in all groups, there was significant (p<0,05) increase of “dipper” 24 hour BP profile patients. Differences of the groups of “dippers” and “non-dippers” by the 12th month of treatment were significant for 3rd and 1st (p=0,0004), 3rd and 2nd (p=0,04) groups with the benefit for group 3.

Conclusion. Two times a day or only evening intake of valsartan with thiazidelike diuretic in the morning facilitated more significant improvement of the main parameters of ABPM, CAP and vascular wall rigidity comparing to just morning intake. B.i.d. valsartan regimen led to significantly (p<0,05) more commonly reached target BP level, improved normalization of 24 hour BP in most of patients, led to more significant improvement of the main ABPM, CAP and vascular stiffness parameters comparing to once daily morning or evening regimen.

Combination treatment with valsartan and amlodipine intensifies evening suppression of Bmal1 clock gene in kidneys of spontaneously hypertensive rats

Blood pressure (BP) rhythm is exhibited in a circadian pattern regulated by complex system of endogenous factors. Administration of pharmacological treatment at the right time can influence the efficacy of treatment; but while kidneys play significant role in BP regulation, little is known about their role in chronopharmacotherapy. This study aimed to compare differences between morning and evening dosing with valsartan and amlodipine combination in both short-term and long-term settings and to elucidate the role of kidneys in chronopharmacology. Spontaneously hypertensive rats aged between 8 and 10 weeks were daily treated with 10mg/kg of valsartan and 4 mg/kg of amlodipine, either in the morning or in the evening with treatment duration of 1 and 6 weeks. After short-term treatment, only morning treatment group demonstrated significantly better outcomes in terms of BP control when compared to placebo. After long-term treatment, both treatment groups gained superior results in BP control against placebo; however, no significant difference was seen between morning and evening treatment. Interestingly, clock gene expression in kidney has been significantly modulated only in the evening-treated groups, with treatment intensifying the reduced Bmal1 levels, while Per2 expression was less altered. However, no direct relation with the outcomes of the therapy has been observed, suggesting that pharmacotherapy may serve as an independent modulator of peripheral circadian clock in the kidney.

mRNA levels of circadian clock components Bmal1 and Per2 alter independently from dosing time-dependent efficacy of combination treatment with valsartan and amlodipine in spontaneously hypertensive rats

Chronopharmacological effects of antihypertensives play a role in the outcome of hypertension therapy. However, studies produce contradictory findings when combination of valsartan plus amlodipine (VA) is applied. Here, we hypothesized different efficacy of morning versus evening dosing of VA in spontaneously hypertensive rats (SHR) and the involvement of circadian clock genes Bmal1 and Per2. We tested the therapy outcome in short-term and also long-term settings. SHRs aged between 8 and 10 weeks were treated with 10 mg/kg of valsartan and 4 mg/kg of amlodipine, either in the morning or in the evening with treatment duration 1 or 6 weeks and compared with parallel placebo groups. After short-term treatment, only morning dosing resulted in significant blood pressure (BP) control (measured by tail-cuff method) when compared to placebo, while after long-term treatment, both dosing groups gained similar superior results in BP control against placebo. However, mRNA levels of Bmal1 and Per2 (measured by RT-PCR) exhibited an independent pattern, with similar alterations in left and right ventricle, kidney as well as in aorta predominantly in groups with evening dosing in both, short-term and also long-term settings. This was accompanied by increased cardiac mRNA expression of plasminogen activator inhibitor-1. In summary, morning dosing proved to be advantageous due to earlier onset of antihypertensive action; however, long-term treatment was demonstrated to be effective regardless of administration time. Our findings also suggest that combination of VA may serve as an independent modulator of circadian clock and might influence disease progression beyond the primary BP lowering effect.

Effect of a dosing-time on quetiapine-induced acute hyperglycemia in mice

Although rare, second-generation antipsychotic drugs cause severe hyperglycemia within several days after the initiation of therapy. Because glucose tolerance exhibits circadian rhythmicity, we evaluated an effect of a dosing-time on quetiapine-induced acute hyperglycemia in mice. A single intraperitoneal dose of quetiapine dosing-time-independently induced insulin resistance in fasted C57BL/6J mice. However, acute hyperglycemic effect was detected only after dosing of the drug at the beginning of an active phase. Under the conditions in which hepatic glucose production was stimulated by pyruvate administration, hyperglycemic effect of quetiapine was dosing-time-independently observed. In addition, the dosing-time-dependent hyperglycemic effect of quetiapine disappeared in the liver-specific circadian clock-disrupted mice in which circadian rhythmicity in hepatic glucose production is deranged. Furthermore, the dosing-time had little impact on the pharmacokinetics of quetiapine in normal mice. These results suggest that quetiapine acutely causes hyperglycemia only when hepatic glucose production elevates. Therefore, quetiapine therapy with once daily dosing at a rest phase might be safer than that at an active phase. Further studies are needed to confirm the hypothesis.

Different chronotherapeutic effects of valsartan and olmesartan in non-dipper hypertensive patients during valsartan treatment at morning

This study was undertaken to evaluate the differences in chronotherapeutic effects of angiotensin-II receptor blockers, valsartan and olmesartan in hypertensive patients with non-dipper blood pressure (BP) pattern during valsartan at morning. Ninety four patients were enrolled, and 40 patients were judged to be non-dippers. In these patients, same dose of valsartan was changed to evening (Val-E, n = 12), or olmesartan (equivalent dose of valsartan) was given at morning (Olm-M, n = 13) or evening (Olm-E, n = 15) for 4 months. BP decreased during sleep and increased during waking hours in Val-E group. In Olm-M and Olm-E groups, BP decreased during sleep and waking hours. Percent reduction in BP at night-time compared to BP at waking hours significantly increased after changing the dose regimen in each group. Serum creatinine decreased and estimated glomerular filtration rate (eGFR) elevated in Olm-M and Olm-E, but not Val-E groups. Positive correlation between systolic BP (SBP) during sleep and serum creatinine, and negative correlation between SBP during sleep and eGFR were detected. These data suggest that dipper BP pattern could be obtained by chronotherapeutic approach using valsartan and olmesartan in non-dipper patients with valsartan at morning. Morning and evening olmesartan, but not evening valsartan improved renal function in these patients.

Chronopharmacodynamics and chronopharmacokinetics of pethidine in mice

BACKGROUND

Many studies have demonstrated that the pharmacokinetics and pharmacodynamics of analgesic drugs vary according to the circadian time of drug administration. This study aims at determining whether the analgesic effect and pharmacokinetics of pethidine in male BALB/c mice are influenced by administration time.

METHODS

A hot-plate test was used to evaluate the analgesic effect after pethidine (20 mg/kg) or saline injection at different dosing times. Mouse blood samples were collected at different intervals after dosing at 9:00 am and 9:00 pm, and were determined via liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

A significant 24-h rhythm was observed in the latency to thermal response at 30 min after dosing, with the peak during the dark phase and the nadir during the light phase. Tolerance to analgesic effect was produced after chronic pethidine injection at 9:00 am or 9:00 pm, and the recovery from tolerance was faster during the dark phase. The peak concentration (Cmax) and area under the concentration-time curve (AUC) of pethidine and its metabolite norpethidine were significantly higher during the dark phase than during the light phase, but the total serum clearance (CL/F) exhibited the opposite trend. The rhythm of drug plasma concentration was positively correlated with the analgesic effect.

CONCLUSION

These results suggest that the pharmacodynamics and pharmacokinetics of pethidine in mice vary significantly according to the dosing time, which implies that the time of administration should be considered in the rational clinical use of pethidine to maximise analgesia and minimise the adverse effects.