Patient description: A 3-day-old Asian female infant presents with jaundice that started a day ago. She was born at 38w3d of gestation, after an uncomplicated pregnancy. The family history is unremarkable. The baby is breastfed. Vital signs are reported as: axillary temperature: 36.3°C, heart rate: 154 beats/min, respiratory rate: 37 breaths/min, and blood pressure: 65/33 mm Hg. Her weight is 3.2 kg, length is 53 cm, and head circumference 36 cm. Her sclera are yellow and her body is icteric. No murmurs or any other abnormalities are detected in the heart and lung auscultation. Her liver and spleen are normal on palpation. Laboratory results are as follows: Serum total bilirubin: 21.02 mg/dL Direct bilirubin of 2.04 mg/dL AST: 37 U/L ALT: 20 U/L GGT: 745 U/L Alkaline phosphatase: 531 U/L Creatinine: 0.3 mg/dL Urea: 29 mg/dL Na: 147 mEq/L K: 4.5 mEq/L CRP: 3 mg/L Complete blood cell count within the normal range. She is diagnosed with uncomplicated neonatal jaundice that may require phototherapy.

Clinical trial eligibility criteria: eligible ages (years): 21.0-55.0,  Pain Healthy male with normal vital signs: systolic blood pressure > 90 mm Hg and < 140 mm Hg; diastolic blood pressure > 50 mm Hg and < 90 mm Hg; pulse 50 to 100 beats per minute; respiratory rate 12 to 20 breathes per minute 2. Between the ages of 21 and 55 years of age 3. Able and willing to give informed consent 4. Able to comply with all study procedures 5. Have adequate hematologic function as evidenced by the following screening results White Blood Cell (WBC) >3,500/mm3 and < 12,000/mm3 Platelet Count > 150,000/mm3 and < 540,000/mm3 Hemoglobin > 12.5 gm/dL and < 20.5 gm/dL. Have adequate liver function as evidenced by the following screening results Aspartate transaminase (AST) ≤ 60 IU/L Alanine transaminase (ALT) ≤ 83 IU Alkaline Phosphatase ≤ 150 IU/L Total Bilirubin ≤ 1.2 mg/dL Prothrombin Time (PT) < 1.2 upper limit of normal (ULN); Partial Thromboplastin Time (PTT) < 1.2 ULN. 6. Electrocardiogram (ECG) within normal limits as determined by the PI 7. Have adequate renal function as evidenced by the following screening result: Glomerular filtration rate (GFR) calculated by Cockcroft-Gault formula >60 ml/min. Urinalysis demonstrating < +1 glucose, +1 ketones, and +1 protein 8. Negative urine test for substances of abuse, including opiates, per clinical research unit (CRU) standards 9. Negative serology tests for HIV, hepatitis B surface antigen and hepatitis C virus antibody 10. Body Mass Index (BMI) 19.0 to 32 kg/m 11. Cold pressor screening results as follows: 1) pain tolerance of > 20 seconds and <120 seconds  Oral temperature > 38°C or history of current illness 2. History of seizures, epilepsy, or recognized increase risk of seizure (e.g., head trauma, metabolic disorders, alcohol or drug withdrawal) 3. History of cirrhosis or laboratory evidence of liver disease 4. Use of alcohol within 24 hours of day -1 until the end of the study; and grapefruit, grapefruit-related citrus fruits (e.g., Seville oranges, pomelos), or grapefruit juice or grapefruit-related juices, or other medication, within 7 days of study drug administration and until the end of the study 5. History of previous anaphylaxis, severe allergic reaction to Tramadol, codeine, or other opioid drugs 6. Use of monoamine oxidase (MAO) inhibitors (including linezolid), Serotonin Reuptake Inhibitors, Serotonin-Norepinephrine Reuptake Inhibitors, and prescription or over-the counter (OTC) medications known to induce or inhibit drug metabolism, including cytochrome P450 2D6 (CYP2D6), and other drugs that may affect the serotonergic neurotransmitter systems including, but not limited to, triptans, dextromethorphan, tricyclic antidepressants, bupropion, lithium, tramadol, dietary supplements such as tryptophan and St. John's Wort, and antipsychotics or other dopamine antagonists. These restrictions are to be maintained from 14 days before study day -1, until the subject completes the study 7. Any other unstable acute or chronic disease that could interfere with the evaluation of the safety of the study drug as determined by the principal Investigator in dialogue with the Sponsor Medical Monitor 8. Unlikely to comply with the study protocol 9. Known or suspected alcohol or drug abuse within the past 6 months 10. Received another investigational agent within 4 weeks of Day 0, or within five half-lives of Day 0, whichever is longer; or receiving any other investigational agent during this study 11. Any concurrent disease or condition that in the opinion of the investigator impairs the subject's ability to complete the trial. Psychological, familial, sociological, geographical or medical conditions which, in the Investigator's opinion, could compromise compliance with the objectives and procedures of this protocol, or obscure interpretation of the trial data