The primary objective of the drug-drug interaction study is to evaluate any drug interaction between the CYP2D6 substrate metoprolol and pyronaridine-artesunate in healthy volunteers.

The primary objective of the pyronaridine-artesunate redosing study is to determine the safety of redosing a 3-day regimen of pyronaridine-artesunate following 60 or 90 days in healthy volunteers.

This was a phase I, open-label, randomised, 2-arm parallel group study in healthy subjects. The study population will include 44 healthy subjects (22 per treatment arm), comprising male and female adults (18-55 years) of any ethnic origin.

Subjects will be randomised to either Arm A or Arm B. Arm A will evaluate pyronaridine-artesunate interference on metoprolol pharmacokinetics (PK) and the effect of a 90-day (±7 days) redosing interval on the safety profile of pyronaridine-artesunate. Arm B will evaluate the effect of a 60-day (±7 days) redosing interval on the safety profile of pyronaridine-artesunate.

Screening will be performed in the 14-day period prior to the first dose. In Arm A, each subject will partake in 3 inpatients periods between: Days -1 to 2, Days 7 to 11, and Days 97 to 101, with dosing on Days 1, 8 to 10, and 98 to 100. In Arm B, each subject will partake in 2 inpatient periods: Days -1 to 4 and Days 60 to 64, with dosing on Days 1 to 3 and 61 to 63. Subjects will be considered to have completed the study at Day 140 (Arm A) or at Day 103 (Arm B).

Any adverse event ongoing at the time of study completion will be followed until resolution unless no further change is expected according to the investigator.

Inclusion Criteria:

1. Male or female subjects between the ages of 18 and 55 years with a body weight between 50 and 90 kg and a body mass index calculated using Quetelet's Index - weight (kg)/height2 (m2) between 18.5-30.0

2. Signed and dated a written informed consent form before undergoing any study related activities

3. Medically normal subjects with no significant abnormal findings at the screening physical examination as evaluated by the investigator

4. Strictly normal values of alanine aminotransferase, aspartate aminotransferase, and total bilirubin and normal or abnormal and clinically insignificant results of the other blood and urine laboratory parameters at screening.

5. Female subjects of non-childbearing potential (i.e. physiologically incapable of becoming pregnant, including any female who was post-menopausal (i.e. one year without menses) or who has undergone sterilization (via hysterectomy or bilateral tubal ligation)

6. Female subjects of childbearing potential with a negative urine pregnancy test at screening confirmed at Day -1 by a serum pregnancy test and who agreed to one of the following methods:

   • Double barrier method of contraception for 2 weeks before first study drug administration and throughout the entire study follow up period
   • Partner(s) who had undergone vasectomy and has been negative for sperm for at least 6 months

7. The ability to understand the requirements of the study and willingness to comply with all study procedures

Exclusion Criteria:

1. Known history or evidence of clinically significant disorders such as cardiovascular (including arrhythmia, acute corrected QT interval greater or equal to 450 milliseconds), respiratory (including active tuberculosis), hepatic, renal, gastrointestinal, immunological (including active HIV-AIDS), neurological (including auditory), endocrine, infectious, malignancy, psychiatric or other abnormality (including head trauma)
2. Known history of hypersensitivity, allergic or adverse reactions to pyronaridine or artesunate or other artemisinins or metoprolol.
3. Other contraindications to pyronaridine use
4. Other contraindications to metoprolol use including second or third degree atrioventricular block, heart rate below 50 beats per minute, uncompensated heart failure or need for treatment with inotropic agents, clinically apparent hypotension, sinus bradycardia or sick sinus syndrome, peripheral arterial disease, pheochromocytoma, asthma, chronic obstructive pulmonary disease, depression and any other condition with in the opinion of the Investigator may be worsened by administration of metoprolol.
5. Known active Hepatitis A IgM (HAV-IgM), Hepatitis B surface antigen (HBsAg) or Hepatitis C antibody (HCV Ab)
6. Seropositive HIV antibody
7. Previous participation in any clinical study with pyronaridine:artesunate (Pyramax)
8. Presence or recent history (last two years) of tobacco abuse (≥10 cigarettes/day)
9. Known or suspected alcohol abuse or illicit drug use 10 years before the study start or positive findings on urine drug screen
10. Intake of alcoholic beverages within 72 hours before study drug administration or caffeine-containing food or beverages, such as coffee, tea, chocolate, or cola, 48 hours before study drug administration
11. Gilbert's disease
12. Administration of any systemic medication or herbal product within 14 days before the first dose of study drug. If the investigator considers that the specific product would not interfere with the safety of the subject or the objectives of the study, topical treatments as well as vitamins and mineral supplements not containing other substances are allowed until 4 days before each dose. Ibuprofen at doses of at most 1200 mg per day for no more than 3 consecutive days or 6 non-consecutive days is allowed until 24h before the first dose of study drug.
13. Plasma donation 3 months before the study start
14. Blood donation of 500 mL or more 3 months before the study start
15. Participation in any clinical study in last 3 months

Arm A: 140 days + follow up if necessary Arm B: 103 days + follow up if necessary

An adverse event is defined as any unfavourable and unintended sign, symptom, syndrome, or illness that developed or worsened during the period of observation in the clinical study.

Clinically relevant abnormal results of diagnostic procedures including abnormal laboratory findings which are considered by the Investigator to be detrimental should be recorded as adverse events whether or not they have a causal relationship with the study drug.