It is well established that increasing the bioavailability of endogenous nitric oxide (NO) protects against cardiovascular diseases. Administering exogenous NO donors is one option to increase endogenous NO levels. Organic nitrates like nitroglycerin have been used as NO donors to protect against angina and ischemic heart failure for over a century. However, their therapeutic value is compromised by rapid development of tolerance during sustained therapy. Hence, these drugs cannot be used as sustain sources of NO. Low-molecular-weight S-nitrosothiols are proven NO donors that have potent vasodilatory, antithrombotic, and anti-inflammatory activities. However, their prophylactic use is hindered by instability after preparation. Inorganic nitrite is emerging as a hypoxic vasodilator, but recent clinical studies indicate that high oral doses of >100 mg/day are required to improve vascular tone. To solve the problems of organic nitrates tolerance, S-nitrosothiol instability, and high nitrite dose requirements, the technique of generating S-nitrosoacetylcysteine (SNOAC) sublingually or in the stomach by reacting sodium nitrite with N-acetylcysteine (NAC) in rodent models was developed. This SNOAC is rapidly absorbed into circulation and increases plasma S-nitrosothiols and reduces systemic systolic and diastolic blood pressure. The major objective of the proposed pre-phase 1 study is to confirm the preclinical findings, including whether the procedure used to generate and deliver NO is feasible in humans using optimal levels of nitrite (2.5mg and 5mg) and NAC (50mg) and a minimum number of subjects. The study will assess the feasibility of using nitrite and NAC mixture sublingually, generation and absorption of SNOAC into circulation, and blood pressure response to the optimum doses of nitrite and NAC. This study will lay the groundwork for determining whether this NO delivery technique can be implemented to initiate comprehensive clinical studies. S-nitrosothiols, nitrite, and nitrate in plasma will be measured by highly sensitive chemiluminescence assay and monitor cardiovascular hemodynamics by FDA-approved mobil-O-graph for ambulatory subjects
The purpose of the study is to increase the in vivo levels of nitric oxide by generating nitric oxide donor compound S-nitrosoacetylcysteine (SNOAC) using the mixture of sodium nitrite and N-acetylcysteine crystals in the sublingual space. The generated SNOAC rapidly diffuses into blood circulation thereby decrease the systemic blood pressure. This compound can be an alternative to organic nitrate NO donor drugs without developing tolerance in patients.