Safety and Ergogenic Properties of Combined Aminophylline and Ambrisentan in Hypoxia

Adjunctive sepsis therapy with aminophylline (STAP): a randomized controlled trial

BACKGROUND

Sepsis is a serious disease caused by infection. Aminophylline has anti-asthma and anti-inflammatory effects. We aimed to explore the safety and effect of aminophylline in sepsis.

METHODS

We conducted a clinical randomized controlled trial involving 100 patients diagnosed with sepsis within 48 h after intensive care unit (ICU) admission in two sites. All patients were randomized in a 1:1 ratio to receive standard therapy with or without aminophylline. The primary clinical outcome was all-cause mortality at 28 days.

RESULTS

From September 27, 2018 to February 12, 2020, we screened 277 septic patients and eventually enrolled 100 patients, with 50 assigned to the aminophylline group and 50 to the usual-care group. At 28 days, 7 of 50 patients (14.0%) in the aminophylline group had died, compared with 16 of 50 (32.0%) in the usual-care group ( P  = 0.032). Cox regression showed that the aminophylline group had a lower hazard of death (hazard ratio = 0.312, 95% confidence interval: 0.129-0.753). Compared with the usual-care group, patients in the aminophylline group had a longer survival time ( P  = 0.039 by the log-rank test). The effects of aminophylline on vasopressor dose, oxygenation index, and sequential organ failure assessment score were time-dependent with treatment. There were no significant differences in total hospitalization days, ICU hospitalization days, and rates of serious adverse events (all P > 0.05). No adverse events were observed in the trial.

CONCLUSIONS

Aminophylline as an adjunct therapy could significantly reduce the risk of death and prolong the survival time of patients with sepsis.

TRIAL REGISTRATION

ChiCTR.org.cn, ChiCTR1800019173.

High-altitude Hypoxia Influences the Activities of the Drug-Metabolizing Enzyme CYP3A1 and the Pharmacokinetics of Four Cardiovascular System Drugs

(1) Background: High-altitude hypoxia has been shown to affect the pharmacokinetic properties of drugs. Although there is a high incidence of cardiovascular disease among individuals living in high-altitude areas, studies on the effect of high-altitude hypoxia on the pharmacokinetic properties of cardiovascular drugs are limited. (2) Methods: The aim of this study was to evaluate the pharmacokinetics of nifedipine, bosentan, simvastatin, sildenafil, and their respective main metabolites, dehydronifedipine, hydroxybosentan, simvastatin hydroxy acid, and N-desmethyl sildenafil, in rats exposed to high-altitude hypoxia. Additionally, the protein and mRNA expression of cytochrome P450 3A1 (CYP3A1), a drug-metabolizing enzyme, were examined. (3) Results: There were significant changes in the pharmacokinetic properties of the drugs in rats exposed to high-altitude hypoxia, as evidenced by an increase in the area under the curve (AUC) and the half-life (t_1/2z) and a decrease in total plasma clearance (CL_z/F). However, most of these changes were reversed when the rats returned to a normoxic environment. Additionally, there was a significant decrease in CYP3A1 expression in rats exposed to high-altitude hypoxia at both the protein and mRNA levels. (4) Conclusions: High-altitude hypoxia suppressed the metabolism of the drugs, indicating that the pharmacokinetics of the drugs should be re-examined, and the optimal dose should be reassessed in patients living in high-altitude areas.

Cardiac-specific knockout and pharmacological inhibition of Endothelin receptor type B lead to cardiac resistance to extreme hypoxia

Oxygen plays a central role in cardiac energy metabolism. At high altitude where the ambient oxygen level is low, we found EDNRB is associated with human hypoxia adaptation. Our subsequent study in global heterozygous knockout mice (Ednrb^-/+) revealed that cardiac function was conserved in these mice when exposed to extreme hypoxia. The major goal of this study was (i) to determine the functional role of cardiomyocyte EdnrB in maintaining cardiac function under hypoxic stress and (ii) to validate the phenotypes we detected in Ednrb^-/+ mice using EDNRB blockers. Unlike the global knockouts, cardiac-specific heterozygote (EdnrB^flox/+) and homozygote (EdnrB^flox/flox) EdnrB knockout mice were phenotypically normal. When treated with graded low levels of oxygen (10% and 5% O₂), both EdnrB^flox/+ and EdnrB^flox/flox were hypoxia tolerant. The cardiac indexes at 10% and 5% O₂ for EdnrB^flox/+ were significantly higher and lactate levels were significantly lower when compared to the cre-negative controls (P < 0.05). Simultaneously, mice treated with BQ-788 (EDNRB-specific blocker) had a significantly higher cardiac index (P < 0.005) and significantly lower lactate levels (P < 0.0001) than in control mice. A similar result was obtained with mice treated with Bosentan (non-specific). These data indicate that a lower level or complete lack of EdnrB in the cardiomyocytes significantly improves cardiac performance under extreme hypoxia, a novel role of cardiomyocyte EdnrB in the regulation of cardiac function. Furthermore, this rescue under extreme hypoxia can also be achieved using EDNRB-specific pharmacological agents, e.g., BQ-788. This systematically confirms, both genetically and pharmacologically, the protective role of a lower EDNRB under extreme hypoxia stress.

KEY MESSAGES

Under normal condition, cardiomyocytes-specific EdnrB knockout mice, both heterozygote and homozygote, are phenotypically normal. Under hypoxic condition, a lower level or complete deletion of cardiomyocyte EdnrB conserves cardiac function by maintaining high cardiac index. Similarly, mice treated with both specific (BQ-788) and non-specific (Bosentan) EDNRB blockers are tolerant to hypoxia by maintaining better cardiac function. The oxygen perfusion under extreme hypoxia is better in the mice with lower EDNRB, as depicted by lower lactate level at 5% oxygen. Our current study systematically confirms, both genetically and pharmacologically, the protective role of a lower EDNRB under extreme hypoxia stress. Overall, it supports our hypothesis that studies on human hypoxia adaptation provide new insight to common disease pathogenesis and treatments.