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SLEEP MEDICINE: Akira Tamura, Yoshiyuki Kawano, Shigeru Naono, Munenori Kotoku, and Jun-ichi Kadota Relationship Between ß-Blocker Treatment and the Severity of Central Sleep Apnea in Chronic Heart Failure Chest 2007; 131: 130-135 [Abstract] [Full text] [PDF]

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Beta blockers reduce testosterone...

James M. Howard   (12 January 2007)

ß-Blockers and Central Sleep Apnea in Chronic Heart Failure

stefan mihaicuta, Daniel Lighezan MD, PhD, Diana Krohn MD   (1 February 2007)

Beta blockers reduce testosterone... 12 January 2007
James M. Howard, Biologist independent Send letter to journal: Re: Beta blockers reduce testosterone... jmhoward{at}anthropogeny.com James M. Howard	It is my hypothesis that excessive testosterone is involved in causing central sleep apnea. Beta blockers reduce testosterone levels. I suggest the findings of Tamura, et al., of a connection of beta blockers with reduced CSA may be due to reduced testosterone.
ß-Blockers and Central Sleep Apnea in Chronic Heart Failure 1 February 2007
stefan mihaicuta, Assistant professor V. Babes University of Medicine and Pharmacy Timisoara Romania, Daniel Lighezan MD, PhD, Diana Krohn MD Send letter to journal: Re: ß-Blockers and Central Sleep Apnea in Chronic Heart Failure mihaicuta{at}yahoo.com stefan mihaicuta, et al.	The most recent treatment guidelines list beta-blockers as standard therapy for cronic heart failure patients.1 Three beta-blockers, carvedilol, metoprolol succinate, and bisoprolol have been shown to improve survival in patients for New York Heart Association (NYHA) Class I - III heart failure.2-4 Carvedilol is a nonselective beta-adrenoreceptor antagonist and an alpha1-adrenoreceptor antagonist that have the ancillary property of vasodilation, manifested by decreased peripheral resistance and decreased blood pressure.5 At high dosages, carvedilol exerts calcium channel blocking activity.6 It also has significant antioxidant properties.7 Carvedilol inhibits the generation of oxygen free radicals and prevents low-density lipoprotein (LDL) oxidation, which, in turn, reduces the uptake of LDL into the coronary vasculature. This antioxidant activity may contribute to carvedilol's cardioprotective effects.8 Possible mechanisms in central sleep apnea is by decreasing the sympathetic nervous system over activity (which enhances central chemosensitivity to CO2) and improving the cardiac function. There are no studies relating beta-blockers to depressed central drive and the hypercapnic chemical response in central sleep apnea. Larger comparative trials may answer the question if there are some differences between beta-blockers.9 The recommended doses are 3.125 mg, 6.25 mg, 12.5 mg, and 25 mg, 50 mg bid10. Why in Tamura et all’s study the doses are so low (the highest was 20 mg/day)? Being so widely used in heart failure, can we aspect to a smaller prevalence of central apnea events in these patients? Bibliography: 1. Adams KF, Lindenfeld J et al. HFSA 2006 Comprehensive Heart Failure Guideline, Journal of Cardiac Failure 2006;12:e1-e122 2. Packer M, Bristow MR, Cohn JN, et al. The effect of carvedilol on morbidity and mortality in patients with chronic heart failure. U.S. Carvedilol Heart Failure Study Group. N Engl J Med. 1996;334:1349-1355. 3. Hjalmarson A, Goldstein S, Fagerberg B, et al. Effects of controlled- release metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in congestive heart failure (MERIT-HF). JAMA. 2000 4. The Cardiac Insufficiency Bisoprolol Study II (CIBIS-II): a randomised trial. Lancet. 1999;353:9-13. 5. Carvedilol. In: Drug facts and comparisons. St. Louis: Facts and Comparisons, 1997:901-4 6. Cohn JN, Archibald DG, Ziesche S, Franciosa JA, Harston WE, Tristani FE, et al. Effect of vasodilator therapy on mortality in chronic congestive heart failure. N Engl J Med 1986;314:1547-52. 7. Yue TL, Cheng HY, Lysko PG, McKenna PJ, Feuerstein R, Gu JL, et al. Carvedilol, a new vasodilator and beta adrenoceptor antagonist, is an antioxidant and free radical scavenger. J Pharmacol Exp Ther 1992;263:92-8 8. Ruffolo RR Jr, Gellai M, Heible JP, Willette RN, Nichols AJ. The pharmacology of carvedilol. Eur J Clin Pharmacol 1990;38(Suppl 2):82-8. 9. Kukin ML, Kalman J, Charney RH, et al. Prospective, randomized comparison of the effect of long-term treatment with metoprolol or carvedilol on symptoms, exercise, ejection fraction and oxidative stress in heart failure. Circulation. 1999;99:2645–2651 10. Chen BP, Chow MS. Focus on carvedilol: a novel beta-adrenergic blocking agent for the treatment of congestive heart failure. Formulary 1997;32(8): 795-805