Phase IIa: Safety, PK, & Tolerability of Sodium Nitrite in Patients With Peripheral Arterial Disease-SONIC

Inclusion Criteria: * The subject is between and including 35 and 85 years of age. * Subjects must be either male or females post-menopausal, sterilized or using suitable birth control. Suitable birth control must be total abstinence, male partner sterilization or double barrier method paired with using oral contraception, injectable progestogen, implants of levonorgestrel, estrogenic vaginal ring, percutaneous contraceptive patches, or intrauterine device (IUD). * History of Peripheral Arterial Disease (PAD) confirmed by medical chart or an ankle brachial pressure index at rest ≤0.90. * If receiving medical standard treatment for cardiac risk factors, subject must have been on a stable treatment for at least 1 month prior to Screening. Treatments must have not changed significantly in the last month and are not expected to change over the duration of the study. * If subjects experience claudication symptoms, subjects must have stable lower extremity symptoms for at least 1 month prior to Screening. * Ability to provide written informed consent and willingness as documented by a signed informed consent form. Exclusion Criteria: * Non-atherosclerotic PAD. * Lower extremity surgical or percutaneous revascularization, evidence of graft failure or other peripheral vascular surgical procedure within last 6 months prior to Screening. * Anticipated lower extremity revascularization within the treatment period. * Myocardial infarction, unstable angina, cerebrovascular accident or transient ischemic attack within 3 months prior to Screening. * Poorly controlled diabetes (HgA1c \> 10.0). * Poorly controlled hypertension (systolic blood pressure (SBP) ≥ 160 mmHg or diastolic blood pressure (DBP) ≥ 100 mmHg) despite therapy. * Systolic blood pressure ≤100 mmHg on current medical regimen. * Hypersensitivity to sodium nitrite or related compounds. * Renal insufficiency documented as eGFR \< 30 mL/minute/1.73 m2. * Pregnant or nursing women. * Life expectancy \< 6 months. * A chronic illness that may increase the risks associated with this study in the opinion of the investigator. * Active malignancy requiring active anti-neoplastic therapy that will, in the opinion of the investigator, interfere with study treatment or participation. * Active infection. * NYHA CHF Class III or IV. * Recent hospitalization (\< 30 days) for acute coronary syndrome, myocardial infarction, congestive heart failure or stroke. * Recent (\< 30 days) coronary revascularization. * Previously treated with angiogenic factors or stem cell therapy within 1 year prior to Screening. * Involvement in another PAD clinical trial within past 1 month prior to Screening. * Exposed tendon, muscle or bone or a diagnosis of critical leg ischemia. * Previous amputation within 3 months prior to Screening or planned amputation that would limit walking (e.g. small toe is allowed). * The subject's ability to perform the 6 minute walk test is limited by symptoms other than claudication. * Current diagnosis of alcohol or other substance abuse. * History of methemoglobinemia, \[met-Hb \> 15%\]. * Inability to speak English (due to need to administer standardized English-language questionnaire). * Evidence of anemia. * History of chronic hemolytic condition, including sickle cell disease. * Chronic use of anti-migraine medication such as Imitrex or sumatriptan. * Have a positive screen for glucose-6-phosphate dehydrogenase deficiency at screening. * Subjects who regularly take the following medications: Allopurinol, PDE-5 inhibitors, sedative tricyclic antidepressants, antihistamines, meperidine and related central nervous system depressants, and nitrates.