Phase I Study of Pyrimethamine in Healthy Japanese and Caucasian Subjects

• Pyrimethamine (Drug): Pyrimethamine will be available as 25 mg tablets. Subjects will be orally administered two pyrimethamine tablets on Day 1 in a fasted condition with 240 mL of water.
• Calcium folinate (Drug): Calcium folinate will be available as 5 mg tablets. Subjects will be orally administered three calcium folinate tablets on Day 1 along with pyrimethamine followed by once daily administration of calcium folinate until Day 8. Each administration will be with 240 mL water.

Primary outcomes

• Maximum Observed Concentration (Cmax) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The Pharmacokinetic (PK) parameters were calculated by non-compartmental analysis. PK Population is defined as all participants who administered at least one dose of study treatment and who have PK sample taken and analyzed.
• Area Under the Concentration-time Curve From Time 0 to t (AUC[0-t]) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Area Under the Concentration-time Curve From Time 0 to Infinity (AUC[0-inf]) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Area Under the Concentration-time Curve From Time 0 to 24 (AUC[0-24]) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Terminal Half-life (t1/2) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Time to Maximum Observed Concentration (Tmax) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Apparent Clearance Following Oral Dosing (CL/F) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Apparent Volume of Distribution Following Oral Dosing (Vd/F) of Pyrimethamine in Healthy Japanese Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.

Secondary outcomes

• Cmax of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• AUC (0-t) of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• AUC (0-inf) of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• AUC (0-24) of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Tmax of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• T1/2 of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• CL/F of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Vd/F of Pyrimethamine in Healthy Caucasian Male Participants [Pre-dose, 1, 2, 4, 6, 12 hours post-dose on Day 1, Day 2, Day 3, Day 4, Day 6, Day 8, Day 15 and Day 22]: Blood samples were collected at indicated time points. The PK parameters were calculated by non-compartmental analysis.
• Number of Participants With Adverse Events (AE) and Serious Adverse Events (SAE) [Up to Day 23]: An AE is any untoward medical occurrence in a clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. Any untoward event resulting in death, life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, congenital anomaly/birth defect, any other situation according to medical or scientific judgment or events associated with liver injury and impaired liver function were categorized as SAE. All participants who take at least one dose of study treatment were included in Safety Population.
• Change From Baseline of Clinical Chemistry Parameters: Glucose, Sodium, Calcium, Potassium, and Urea. [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of clinical chemistry parameters including glucose, sodium, calcium, potassium, and urea at indicated time points. Day -1 value was defined as Baseline for clinical chemistry parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline of Clinical Chemistry Parameters: Alkaline Phosphatase, Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST) [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of clinical chemistry parameters including alkaline phosphatase, ALT and AST at indicated time points. Day -1 value was defined as Baseline for clinical chemistry parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline of Clinical Chemistry Parameters: Direct Bilirubin, Bilirubin, Creatinine. [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of clinical chemistry parameters including direct bilirubin, bilirubin and creatinine at indicated time points. Day -1 value was defined as Baseline for clinical chemistry parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline of Clinical Chemistry Parameters: Protein [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of clinical chemistry parameter including protein at indicated time points. Day -1 value was defined as Baseline for clinical chemistry parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameters: Basophils, Eosinophils, Lymphocytes, Monocytes, Neutrophils, Platelet and Leukocytes [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameters including basophils, eosinophils, lymphocytes, monocytes, neutrophils, platelet and leukocytes at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value. Data was not available as all basophil values were below the detection limit. Hence, the change from baseline in basophil values were not calculated.
• Change From Baseline in Hematology Parameter: Reticulocytes [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including reticulocytes at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameter: Hematocrit [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including hematocrit at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameter: Hemoglobin [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including hemoglobin at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameter: Mean Corpuscular Hemoglobin [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including mean corpuscular hemoglobin at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameter: Mean Corpuscular Volume [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including mean corpuscular volume at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Hematology Parameter: Erythrocytes [Baseline (Day -1), 24, 96, 168, 336 hours and follow up (504 hours)]: Blood samples were collected for the analysis of hematology parameter including erythrocytes at indicated time points. Day -1 value was defined as Baseline for hematology parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Number of Participants With Abnormal Urinalysis Parameter [Day -1, 24, 96, 168, 336 and follow up (504 hours)]: The dipstick test gives results in a semi-quantitative manner, and results for urinalysis parameters of can be read as Trace, + and ++ indicating proportional concentrations in the urine sample. Only participants with abnormal findings for urinalysis at any visit has been presented.
• Specific Gravity at Indicated Time Points [Day -1, 24, 96, 168, 336 hours and follow up (504 hours)]: Urine samples were collected for analysis of specific gravity of urine. Urinary specific gravity is a measure of the concentration of solutes in the urine. It measures the ratio of urine density compared with water density and provides information on the kidney's ability to concentrate urine.
• Urine Potential of Hydrogen (pH) at Indicated Time Points [Day -1, 24, 96, 168, 336 hours and follow up (504 hours)]: Urine samples were collected for analysis of urine pH. pH is calculated on a scale of 0 to 14, values on the scale refer to the degree of alkalinity or acidity. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic. Normal urine has a slightly acid pH (5.0 - 6.0).
• Change From Baseline in Diastolic Blood Pressure (DBP) and Systolic Blood Pressure (SBP) [Baseline (Pre-dose on Day 1), 4, 12, 24, 48, 72, 96, 120, 144, 168, 336 and 504 hours]: Blood pressure of participants were measured at indicated time points in semi-supine position after 5 minutes rest. Day 1 (Pre-dose) value was defined as Baseline for vital sign parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Pulse Rate [Baseline (Pre-dose on Day 1), 4, 12, 24, 48, 72, 96, 120, 144, 168, 336 and 504 hours]: Pulse rate of participants were measured at indicated time points in semi-supine position after 5 minutes rest. Day 1 (Pre-dose) value was defined as Baseline for vital sign parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline in Temperature [Baseline (Pre-dose on Day 1), 4, 12, 24, 48, 72, 96, 120, 144, 168, 336 and 504 hours]: Temperature of participants were measured at indicated time points in semi-supine position after 5 minutes rest. Day 1 (Pre-dose) value was defined as Baseline for vital sign parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline of Electrocardiogram (ECG) Parameters: PR Interval, QRS Duration, QT Interval, and QT Interval Corrected for Heart Rate by Fredericia's Formula (QTcF) Interval [Baseline (Pre-dose on Day 1), 4, 12, 24, 48, and 504 hours]: A single 12-lead ECG was obtained at indicated time points using an ECG machine that automatically measures PR, QRS, QT, and QTcF intervals. Day 1 (Pre-dose) value was defined as Baseline for ECG parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.
• Change From Baseline of ECG Parameter: ECG Mean Heart Rate [Baseline (Pre-dose on Day 1), 4, 12, 24, 48, and 504 hours]: A single 12-lead ECG was obtained at indicated time points using an ECG machine that automatically calculates mean ECG heart rate. Day 1 (Pre-dose) value was defined as Baseline for ECG parameters. Change from Baseline was defined as difference between post-dose visit values minus Baseline value.

Sex: Male, ages: 20 Years to 64 Years, accepts healthy volunteers

Inclusion Criteria:

* Subjects should be between 20 and 64 years of age inclusive, at the time of signing the informed consent.
* Subjects who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests and cardiac monitoring.
* Body weight >= 50 kilograms (kg) and body mass index (BMI) within the range 18.5 to 30.0 kilogram per square meters (kg/m\^2) (inclusive).
* Japanese or Caucasian male.
* A male subject must agree to use contraception during the treatment period and until follow-up.
* Japanese ethnic origin defined as having been born in Japan, having four ethnic Japanese grandparents, holding a Japanese passport or identity papers and being able to speak Japanese. Subjects should also have lived outside Japan for less than 10 years at the time of screening.
* Caucasian subject will be defined as an individual having four grandparents who are all descendants of the original people of Europe.
* Capable of giving signed informed consent which includes compliance with the requirements and restrictions of the study.

Exclusion Criteria:

* Alanine aminotransferase (ALT) > 1.5 times upper limit of normal (ULN).
* Bilirubin > 1.5 times ULN (isolated bilirubin > 1.5 times ULN is acceptable if bilirubin is fractionated and direct bilirubin < 35 percent).
* QT interval corrected for heart rate according to Fridericia's formula (QTcF) > 450 milliseconds (msec).
* Current or chronic history of liver disease, or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).
* History of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, or neurological disorders capable of significantly altering the absorption, metabolism, or elimination of drugs; constituting a risk when taking the study treatment; or interfering with the interpretation of data.
* Abnormal blood pressure as determined by the investigator.
* Hematological values: outside normal range at screening.
* Serum creatinine level: outside normal range at screening visit.
* Past or intended use of over-the-counter or prescription medication including herbal medications within 14 days prior to dosing.
* Participation in the study would result in loss of blood or blood products in excess of 500 milliliters (mL) within 3 months.
* Exposure to more than 4 new chemical entities within 12 months prior to the first dosing day.
* Current enrollment or past participation within the last 30 days before signing of consent in this clinical study involving an investigational study treatment or any other type of medical research.
* Presence of Hepatitis B surface antigen (HBsAg) at screening or positive Hepatitis C antibody test result at screening. Subjects with positive Hepatitis C antibody due to prior resolved disease can be enrolled, only if a confirmatory negative Hepatitis C RNA test is obtained.
* Positive Hepatitis C ribonucleic acid (RNA) test result at screening or within 3 months prior to first dose of study treatment. Test is optional and subjects with negative Hepatitis C antibody test are not required to also undergo Hepatitis C RNA testing.
* Positive pre-study drug/alcohol screen.
* Positive human immunodeficiency virus (HIV) antibody test.
* Regular use of known drugs of abuse.
* Regular alcohol consumption within 6 months prior to the study defined as: For an average weekly intake of > 14 units for males. One unit is equivalent to 10 grams (g) of alcohol: a can of mid-strength (equivalent to 375 mL) beer, 1 glass (100 mL) of table wine or 1 measure (30 mL) of spirits (including rice wine).
* History or regular use of tobacco- or nicotine-containing products within 6 months prior to screening.
* Sensitivity to any of the study treatments, or components thereof, or drug or other allergy that, in the opinion of the investigator or medical monitor, contraindicates participation in the study.

Participant flow

Outcome results

• Maximum Observed Concentration (Cmax) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Nanogram per milliliter: Healthy Japanese Participants 430.5 +/- 13.3
• Area Under the Concentration-time Curve From Time 0 to t (AUC[0-t]) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Hours* nanogram per milliliter: Healthy Japanese Participants 59013.1 +/- 15.3
• Area Under the Concentration-time Curve From Time 0 to Infinity (AUC[0-inf]) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Hours* nanogram per milliliter: Healthy Japanese Participants 64670.3 +/- 16.6
• Area Under the Concentration-time Curve From Time 0 to 24 (AUC[0-24]) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Hours* nanogram per milliliter: Healthy Japanese Participants 8756.3 +/- 8.0
• Terminal Half-life (t1/2) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Hours: Healthy Japanese Participants 122.75 +/- 21.499
• Time to Maximum Observed Concentration (Tmax) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Median, Hours: Healthy Japanese Participants 2.000 (1.00 to 6.00)
• Apparent Clearance Following Oral Dosing (CL/F) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Milliliter per hour: Healthy Japanese Participants 773.2 +/- 16.6
• Apparent Volume of Distribution Following Oral Dosing (Vd/F) of Pyrimethamine in Healthy Japanese Male Participants (Primary), Geometric mean, Milliliter: Healthy Japanese Participants 135330.9 +/- 5.5
• Cmax of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Nanogram per milliliter: Healthy Caucasian Participants 371.1 +/- 10.0
• AUC (0-t) of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Hours* nanogram per milliliter: Healthy Caucasian Participants 41582.0 +/- 26.9
• AUC (0-inf) of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Hours* nanogram per milliliter: Healthy Caucasian Participants 44869.1 +/- 27.0
• AUC (0-24) of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Hours* nanogram per milliliter: Healthy Caucasian Participants 6930.8 +/- 19.3
• Tmax of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Median, Hours: Healthy Caucasian Participants 1.000 (1.000 to 6.00)
• T1/2 of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Mean, Hours: Healthy Caucasian Participants 99.46 +/- 20.745
• CL/F of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Milliliters per hour: Healthy Caucasian Participants 1114.4 +/- 27.0
• Vd/F of Pyrimethamine in Healthy Caucasian Male Participants (Secondary), Geometric mean, Milliliters: Healthy Caucasian Participants 157125.8 +/- 16.8
• Number of Participants With Adverse Events (AE) and Serious Adverse Events (SAE) (Secondary), Count of participants, Participants: Healthy Japanese Participants 2; Healthy Caucasian Participants 6
• Change From Baseline of Clinical Chemistry Parameters: Glucose, Sodium, Calcium, Potassium, and Urea. (Secondary), Mean, Millimoles per liter: Healthy Japanese Participants -0.33 +/- 0.403; Healthy Caucasian Participants -0.26 +/- 0.310
• Change From Baseline of Clinical Chemistry Parameters: Alkaline Phosphatase, Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST) (Secondary), Mean, International units per liter: Healthy Japanese Participants -9.0 +/- 11.60; Healthy Caucasian Participants -3.3 +/- 5.71
• Change From Baseline of Clinical Chemistry Parameters: Direct Bilirubin, Bilirubin, Creatinine. (Secondary), Mean, Micromoles per liter: Healthy Japanese Participants 0.7 +/- 1.98; Healthy Caucasian Participants 0.6 +/- 0.53
• 16 more outcome measures not shown.

Adverse events

Time frame: Serious adverse events (SAEs) and non-serious AEs were collected up to Day 23

Other adverse events by term

• Iida T, Nand RA, Ino H, Ogura H, Itoh H, Igarashi H, Numachi Y, Gross AS. Evaluation of the Pharmacokinetics, Safety, and Tolerability of a Single Oral Dose of Pyrimethamine in Healthy Male Subjects of Japanese and European Ancestry. Clin Pharmacol Drug Dev. 2020 Aug;9(6):768-773. doi: 10.1002/cpdd.771. Epub 2020 Jan 16. PMID 31950646

• Study Protocol (PDF, 2017-07-19)
• Statistical Analysis Plan (PDF, 2017-09-15)

• GSK Clinical Trials, Study director, GlaxoSmithKline