Effect of doxazosin GITS on 24-hour blood pressure profile in patients with stage 1 to stage 2 primary hypertension

Circadian rhythms in blood pressure, heart rate, hormones, and on polysomnographic parameters in severe obstructive sleep apnea syndrome patients: effect of continuous positive airway pressure

INTRODUCTION

Seventeen male patients with severe obstructive sleep apnea syndrome (OSAS; apnea-hypopnea index>30/h) were monitored by polysomnography in the sleep lab before and after about 8 weeks of continuous positive airway pressure (CPAP). Twelve of the patients were hypertensive, but treated by antihypertensive drugs. The circadian rhythms in blood pressure (BP) and heart rate were determined by ambulatory BP monitoring and motor activity was monitored by a motion logger. As the sympathetic tone is reported to be increased in sleep apnea, the circadian rhythm in plasma norepinephrine was studied in parallel and as a marker rhythm of the biological clock plasma melatonin was determined around the clock by radioimmunoassay.

RESULTS

Level and rhythm in BP and heart rate were not significantly affected by CPAP in this group of patients, but the number of dippers increased after CPAP intervention. The high 24 h plasma values of norepinephrine were lowered by CPAP therapy. In contrast, melatonin values were disturbed in OSAS patients with a loss in nocturnal increase; this pattern was not corrected by CPAP. Sleep functions (deep sleep, slow wave sleep, rapid eye movement sleep, arousal index, apnea-hypopnea index, desaturation index) were disturbed in OSAS patients as monitored by polysomnography and were significantly improved by CPAP therapy.

CONCLUSION

The study indicates that BP-controlled hypertensive patients with OSAS can additionally benefit from CPAP therapy by increasing the number of dippers. This treatment significantly improved sleep functions and OSAS symptoms. In addition, arousal movements at night were also reduced and the high sympathetic tone during early morning hours was also decreased. However, there is still an indication of a disturbed function of the biological clock as the loss in the rhythm in plasma melatonin was not corrected by CPAP.

Administration-time differences in effects of hypertension medications on ambulatory blood pressure regulation

Specific features of the 24-h blood pressure (BP) pattern are linked to progressive injury of target tissues and risk of cardiovascular disease (CVD) events. Several studies have consistently shown an association between blunted asleep BP decline and risk of fatal and nonfatal CVD events. Thus, there is growing focus on ways to properly control BP during nighttime sleep as well as during daytime activity. One strategy, termed chronotherapy, entails the timing of hypertension medications to endogenous circadian rhythm determinants of the 24-h BP pattern. Significant and clinically meaningful treatment-time differences in the beneficial and/or adverse effects of at least six different classes of hypertension medications, and their combinations, are now known. Generally, calcium channel blockers (CCBs) are more effective with bedtime than morning dosing, and for dihydropyridine derivatives bedtime dosing significantly reduces risk of peripheral edema. The renin-angiotensin-aldosterone system is highly circadian rhythmic and activates during nighttime sleep. Accordingly, evening/bedtime ingestion of the angiotensin-converting enzyme inhibitors (ACEIs) benazepril, captopril, enalapril, lisinopril, perindopril, quinapril, ramipril, spirapril, trandolapril, and zofenopril exerts more marked effect on the asleep than awake systolic (SBP) and diastolic (DBP) BP means. Likewise, the bedtime, in comparison with morning, ingestion schedule of the angiotensin-II receptor blockers (ARBs irbesartan, olmesartan, telmisartan, and valsartan exerts greater therapeutic effect on asleep BP, plus significant increase in the sleep-time relative BP decline, with the additional benefit, independent of drug terminal half-life, of converting the 24-h BP profile into a more normal dipping pattern. This is the case also for the bedtime versus upon-awakening regimen of combination ARB-CCB, ACEI-CCB, and ARB-diuretic medications. The chronotherapy of conventional hypertension medications constitutes a new and cost-effective strategy for enhancing the control of daytime and nighttime SBP and DBP levels, normalizing the dipping status of their 24-h patterning, and potentially reducing the risk of CVD events and end-organ injury, for example, of the blood vessels and tissues of the heart, brain, kidney, and retina.

Controlled‐Release Doxazosin as Combination Therapy in Hypertension: The GATES Study

Doxazosin gastrointestinal therapeutic system (GITS) or placebo was added to the antihypertensive therapy of uncontrolled hypertensive patients in a prospective, randomized, double-blind trial. Patients received doxazosin GITS 4 mg/d (n=89) or placebo (n=86) for 6 weeks in addition to entry antihypertensive medication. Doxazosin GITS was increased to 8 mg/d after 2 or 4 weeks if patients did not respond (sitting blood pressure <140/90 mm Hg and 10/10-mm Hg decrease from baseline). Reductions from baseline in sitting and standing blood pressures were greater with doxazosin GITS than placebo at all time points (p</=0.017) except Week 1 sitting systolic pressure (p=0.068). The response rate was greater in the doxazosin GITS group (37.3%) than the placebo group (10.7%; p<0.001). With the exception of postural hypotension (7% compared with 0.0%), the frequency of adverse events was similar for doxazosin GITS and placebo. Doxazosin GITS was effective as combination antihypertensive therapy with the major classes of antihypertensive agents.

Doxazosin GITS versus standard doxazosin in mild to moderate hypertension

BACKGROUND

The selective alpha 1-adrenoceptor antagonist doxazosin in both standard formulation and gastrointestinal therapeutic system (GITS) controlled-release formulation is effective for hypertension without having a negative impact on serum lipids. This study was designed to compare the relative efficacy of these two formulations of doxazosin on clinic and ambulatory blood pressure and serum lipids in patients with mild to moderate hypertension.

METHODS

Hypertensive patients aged 18-70 years (n = 335) were evaluated in a multi-center prospective randomized study. Following a 2-week placebo run-in phase, patients were randomized to receive doxazosin 2 or 4 mg, with dose titration, or doxazosin GITS 4 mg, no dose titration, for 9 weeks.

RESULTS

Both doxazosin formulations reduced clinic diastolic and systolic blood pressure from baseline (P < 0.0001). Doxazosin GITS and doxazosin 4 mg had similar blood pressure-lowering effects. Doxazosin GITS reduced sitting diastolic and systolic blood pressure compared with doxazosin 2 mg (P < 0.01 for both). A greater proportion of the doxazosin GITS group reached goal blood pressure (< or = 140/90 mm Hg) after 9 weeks compared with the doxazosin 2-mg group. All doses of doxazosin reduced 24-h and daytime (7:00 am to 10:00 pm) ambulatory blood pressure from baseline (all P < 0.01). Doxazosin GITS significantly reduced nighttime (10:00 pm to 7:00 am) ambulatory blood pressure from baseline. A neutral effect on serum lipids was observed with doxazosin.

CONCLUSIONS

Doxazosin GITS and doxazosin were effective in reducing clinic and ambulatory blood pressure. The GITS formulation reduced the need for dose titration. Both doxazosin formulations were well tolerated.

Clinical ease of using doxazosin in BPH patients with and without hypertension

Clinical studies have demonstrated that doxazosin therapy reduced blood pressure (BP) in patients with benign prostatic hyperplasia (BPH) who were hypertensive at baseline but not in patients who were physiologically or pharmacologically normotensive at baseline. In patients with BPH and uncontrolled hypertension, despite treatment with other antihypertensive drugs, the addition of doxazosin resulted in improved control with significant reductions in BP. The new formulation, doxazosin gastrointestinal therapeutic system (GITS), is initiated at a therapeutic dose, simplifying dose titration. Based on its efficacy and pharmacokinetic and tolerability profiles, doxazosin GITS is an effective and well-tolerated treatment for normotensive and hypertensive patients with BPH.