Growth hormone: a promising treatment for the failing heart?

Many pathologic processes that accelerate the progression of heart failure, such as cardiac remodeling and impaired contractility, may be modulated by administration of recombinant growth hormone. The agent improves structural and functional aspects of the failing heart both in the short term and after several months of therapy. However, conflicting clinical results cast doubt on whether it has a clear benefit in all of these patients. In addition, growth hormone therapy may be associated with cardiac and noncardiac adverse effects. Many questions must be addressed before its place in heart failure therapy is established. Optimal patient population, dosing regimen, duration of therapy, and effect on patient survival are unknown. Until larger, blinded studies are completed, growth hormone therapy remains an investigational approach to managing refractory heart failure.

Albuterol delivery in a neonatal ventilated lung model: Nebulization versus chlorofluorocarbon- and hydrofluoroalkane-pressurized metered dose inhalers.

The aim of this study was to compare albuterol delivery in a neonatal ventilated lung model, using three delivery methods: 1) jet nebulizer; 2) chlorofluorocarbon-pressurized metered dose inhaler (CFC-MDI) actuated into an ACE(R) spacer; and 3) hydrofluoroalkane-pressurized MDI (HFA-MDI) actuated into an ACE(R) spacer. The bench model consisted of a mechanically ventilated infant test lung with ventilator settings to simulate a very low birth weight neonate with moderate lung disease. Albuterol solution (0.5%) was nebulized at the humidifier and temperature port, 125 cm and 30 cm from the Y-piece, respectively. Albuterol metered dose inhalers (MDIs) were actuated into an ACE(R) spacer that was tested in two positions: 1) inline between the endotracheal (ET) tube and the Y-piece; and 2) attached to the ET tube and administered by manual ventilation. Albuterol was collected on a filter at the distal end of the ET tube and was quantitatively analyzed by high performance liquid chromatography. Albuterol delivery by CFC-MDI (position 1, 4.8 +/- 1.0%, vs. position 2, 3.8 +/- 1.6%, P > 0.05) and HFA-MDI (position 1, 5.7 +/- 1.6%, vs. position 2, 5.5 +/- 2.4%, P > 0.05) were significantly greater than delivery by nebulization at 30 cm (0.16 +/- 0.07%) and 125 cm (0.15 +/- 0.03%) from the Y-piece (P < 0.001). A single actuation of albuterol MDI delivered the equivalent of nebulizing 2.5-3.7 mg of albuterol solution. We conclude that albuterol administered by MDI and ACE(R) spacer resulted in more efficient delivery than by nebulization in this mechanically ventilated neonatal lung model. There was no significant difference in drug delivery between CFC-MDI and HFA-MDI; nor did the placement of the spacer significantly affect drug delivery.

A chronobiologic approach to the pharmacotherapy of hypertension and angina.

OBJECTIVE: To review the chronobiology of hypertension and coronary artery disease and the application of chronotherapeutics to their treatment and prevention. DATA SOURCES: Clinical trials and review articles (English-language) on the topic of chronotherapy and cardiovascular disease were identified via a MEDLINE search from 1990 to March 2000, using the search terms chronotherapy, circadian rhythm, cardiovascular disease, hypertension, and angina. DATA EXTRACTION: Search and evaluation focused on published clinical trials and review articles of circadian variation associated with pharmacotherapy for cardiovascular disease. DATA SYNTHESIS: The existence of circadian rhythm in cardiovascular disease is well established. Heart rate and blood pressure peak during the morning hours and reach a nadir at bedtime. The incidence of myocardial infarction, stroke, sudden cardiac death, and myocardial ischemia also increases during the early-morning hours. Based on these relationships, researchers have begun to apply the science of chronotherapeutics, or timing of drug effect with biologic need, to improve cardiovascular outcomes. This includes administering traditional agents at specific times throughout the day and developing new agents--chronotherapeutic formulations with special release mechanisms--targeted at inducing the greatest effect during the morning surges. Chronotherapeutic agents are specifically designed to provide peak plasma concentrations during the early-morning hours, when effect appears most needed; lowest concentrations occur at night, when heart rate and blood pressure are lowest and, consequently, cardiovascular events are least likely to occur. CONCLUSIONS: Whether chronotherapy of cardiovascular disease offers an advantage in long-term outcomes over traditional therapy must be studied in clinical trials.