The antihypertensive valsartan is better at lowering blood pressure in patients with obstructive sleep apnea (OSA) than continuous positive airway pressure (CPAP), French researchers say.
They also report that CPAP and valsartan together have a synergistic effect that reduces blood pressure significantly in patients who don't respond to either treatment alone.
In their paper, published online June 3 in the American Journal of Respiratory and Critical Care Medicine, Dr. Jean-Louis Pepin at Grenoble University Hospital and colleagues said that angiotensin II receptor antagonists like valsartan are a logical choice because the hypoxia associated with OSA may lead to over-activity of the renin-angiotensin system.
Forty-seven patients were eligible for the crossover study, but 14 were excluded for not meeting inclusion criteria and five refused to participate.
The remaining 28 were randomized to either eight weeks of 160 mg valsartan daily or CPAP. Following a four-week washout period, the patients in each arm then crossed-over and completed the other treatment arm.
Patients in the study were moderately obese and had moderate-to-severe OSA. Twenty-three completed the study, with three refusing to continue and two withdrawing because of valsartan-related side effects.
Decreases in blood pressure were larger with valsartan compared to CPAP for all blood pressure parameters, including daytime and nighttime mean blood pressure and 24-hour mean blood pressure.
Twenty-four hour mean blood pressure decreased by 9.1 mmHg from baseline with valsartan (p<0.001) vs. 2.1 mmHg with CPAP (p<0.01), for a mean difference of 7.0 mmHg (p<0.001).
Following the 20-week crossover trial, 11 patients who didn't respond to either valsartan or CPAP alone were enrolled in an 8-week study combining the two treatments. Combination therapy led to a drop in all blood pressure measurements, which was most noticeable for blood pressure measured in the doctor's office and for nighttime blood pressure.
"The fact that CPAP and valsartan had additive effects suggests different modalities of action," the investigators wrote.
Because non-compliance with CPAP can be as high as 20%, they advise that angiotensin II receptor blockers should be used in OSA patients with comorbid conditions who have poor CPAP compliance or who refuse CPAP altogether. They also recommend that angiotensin II receptor blockers be used in patients who have severe, but symptom-free, sleep apnea and hypertension, and in patients who do not respond to CPAP alone.
The study was funded by Novartis, which markets valsartan as Diovan, and by Weinmann. None of the authors disclosed any conflicts of interest relating to the study.
Am J Respir Crit Care Med 2010.
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