Acetic acid, 2-[(5-chloro-8-quinolinyl)oxy]-

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 2012 to July 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Objective of study:

toxicokinetics

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

July 2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.7485 (Metabolism and Pharmacokinetics)

Version / remarks:

August 1998

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method B.36 (Toxicokinetics)

Version / remarks:

2008

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF (2000) Metabolism Study

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

[(5-chloroquinolin-8-yl)oxy]acetic acid

Cas Number:

88349-88-6

Molecular formula:

C11H8ClNO3

IUPAC Name:

[(5-chloroquinolin-8-yl)oxy]acetic acid

Test material form:

solid: particulate/powder

Remarks:

powder

Specific details on test material used for the study:

- Name of test material (as cited in study report): X204558
- Molecular formula: C11H8ClNO3
- Molecular weight: 237.6
- Analytical purity: 98.3% +/- 0.03% wt/wt by liquid chromatography with identification by liquid chromatography mass spectrometry, gas chromatography mass spectrometry, and nuclear magnetic resonance
- Lot/batch No.: Lot 2GHB0002; TSN303795
- Radiochemical purity (if radiolabelling): 100% by high performance liquid chromatography and thin layer chromatography with identification by mass spectrometry (Lot 54588-13-15, INV303628)
- Specific activity (if radiolabelling): 39.32 mCi/mmol
- Locations of the label (if radiolabelling): {[5-chloro(4a,5,6,7,8,8a-UL-14C)quinolin-8-yl]oxy}acetic acid Or Cloquintocet-Ph-UL-14C

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Fischer 344

Remarks:

F344/NTac

Details on species / strain selection:

Species as recommended by the guideline; the strain was selected due to their general acceptance and suitability for toxicity testing, the availability of background data and the reliability of the commercial supplier

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic (Germantown, New York)
- Age at study initiation: 11 weeks
- Weight at study initiation: Males: 0.208 - 0.235 g, Females: 0.116 - 0.156 g
Weight variations among male and female animals did not exceed ± 20% of the mean weight.
- Fasting period before study: For Groups 1-3 access to feed was restricted approximately 16 hours prior to the administration of test material and was returned about 4 hours post-dosing. For animals in Group 5 (repeat), access to feed was restricted only prior to the last dose (radiolabeled test material). Animals in Group 4 (IV) did not have their feed restricted prior to dose administration.
- Housing: Non-cannulated animals were housed two per cage in stainless steel solid bottom cages with corncob bedding prior to randomization. Following administration of radiolabeled test material, the animals were housed singly in glass Roth-type metabolism cages, which were designed for the separation and collection of urine, feces, CO2, and organic volatiles.
- Individual metabolism cages: yes.
- Diet: ad libitum LabDiet Certified Rodent Diet #5002
- Water: ad libitum municipal water
- Acclimation period: Animals were acclimated to the laboratory environment for at least one week prior to use, including at least two days in metabolism cages. Jugular vein cannulated rats (surgery performed by the supplier) were acclimated in metabolism cages forat least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C with a tolerance of ± 1°C (and a maximum permissible excursion of ± 3°C)
- Humidity (%): 46-65%
- Air changes (per hr): 12-15 times/hour (average)
- Photoperiod (hrs dark / hrs light): 12-hour light/dark

Administration / exposure

Route of administration:

other: Oral gavage and intravenous

Vehicle:

other: 0.5% w/v methylcellulose for oral gavage and 20/60/20% v/v/v ethyl alcohol/polyethylene glycol 400/saline for intravenous

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Oral - gavage:
- The appropriate quantity of radiolabeled test substance was added to 0.5% w/v methylcellulose to prepare the dose suspension. The amount of dose suspension was administered at a target volume of ~5 mL/kg bw; the target radioactivity was ~500 μCi/kg. Appropriate amounts of 14C-labeled and/or non-radiolabeled X204558 were added to obtain the target doses of 5 or 75 mg X204558/kg bw (Groups 1, 2, and 5).

- The volume of radiolabeled dose formulation administered to each animal was calculated based on the body weight taken on the day of dose administration, with the exception of Group 5 (repeat). The volume of dose administered to each Group 5 animal was based on the body weight taken on day 1 (for dosing days 1-7) and day 8 (for dosing days 8-14) of dose administration. The volume of radiolabeled dose administered on day 15 was based on individual body weights on either day 14 or 15. The actual amount of radiolabeled test material administered to each animal was determined by weighing the dose syringe before and after dose administration. The target volume of the radiolabeled dose formulation was 5 mL/kg bw. The amount of non-radiolabeled test material administered to Group 5 (days 1-14) animals was determined by target volume, not syringe weight.

Intravenous:
- Appropriate amounts of labeled and unlabeled X204558 were added to obtain the target radioactivity of 500 μCi/kg bw. Appropriate amounts of labelled and unlabeled X204558 was added to 20/60/20 % v/v/v ethyl alcohol/polyethylene glycol 400/saline to obtain the appropriate dose of 5 mg 14CX204558/ kg bw. The amount of dose solution administered was targeted at ~2.5 g/kg bw and injected over a minimum of 45 seconds which corresponded to injection rates ranging from 0.7 to 0.8 mL/minute.

METHOD OF INTRAVENOUS INJECTION:
- Intravenous injection (Group 4) was conducted by injecting the dosing solution into indwelling jugular vein cannulae. A small volume (~0.05 mL) of blood was drawn from the cannula and discarded; this removed any heparin locking solution before injecting the test material. The test material was then injected slowly through the cannula. To insure that all test material was injected into the animal, the cannula was rinsed, first by drawing and pushing blood (2-3 times) back into cannula and finally by flushing the cannula with ~0.3 mL of heparinized saline (~20 - 40 unit/mL). Animals were administered 2.5 mL/kg body weight over a period of at least 45 seconds or ~0.8 mL/min. Every attempt was made to maintain sterile conditions, using sterile syringes, autoclaved vials, and sterile commercially available vehicles. Dose solution was administered at room temperature (22 ± 3oC). After dosing the animal, the syringe and extension were rinsed in methanol and analyzed for radioactivity by LSS. The actual amount of dose administered was calculated by subtracting out the residual radioactivity that remained in the solvent wash.

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
- Homogeneity: Chemical and radiochemical homogeneity of the dose suspension (oral) and dose solution (IV) were determined by analyzing aliquots of the dose taken from various locations within the dosing container.
- Stability: Fifteen days of stability of non-radiolabeled X204558 in the oral dosing carrier at the 5 mg/kg bw concentration was determined concurrently with the study, but prior to the start of the repeated dose group (Group 5). The test material was analyzed on Days 1, 7 and 16 and stirred continuously at ambient temperature via high performance liquid chromatography with ultraviolet detection (HPLC/UV).
- Dose Confirmation and Homogeneity of Dose Suspensions and Solution The concentration of X204558 in the dose suspensions (oral) or solution (IV) was determined in accordance with the standard operating procedures of the Analytical Chemistry Laboratory. Dose confirmation was determined by high-performance liquid chromatography with ultraviolet (HPLC-UV). Liquid scintillation spectroscopy (LSS) analysis of aliquots of the 14C-labeled dosing suspensions or solution taken from various locations in the dosing container were used to confirm the concentration of radioactivity and the radiochemical homogeneity of 14C-X204558.

Duration and frequency of treatment / exposure:

Group 1 received a single oral dose of 5 mg/kg 14C-X204558.
Group 2 received a single oral dose of 75 mg/kg 14C-X204558.
Group 4 received a single IV dose of 5 mg/kg 14C-X204558.
Group 5 animals (5 male and 5 female rats) received 14-daily doses of 5 mg/kg non-radiolabeled X204558. On day 15, each Group 5 animal (4 male and 4 female rats) received a single dose of 5 mg/kg 14C-X204558.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

5 mg/kg bw/day (nominal)

Remarks:

Group 1 (oral)

Doses / concentrations 2

Dose / conc.:

75 mg/kg bw/day (nominal)

Remarks:

Group 2 (oral)

Doses / concentrations 3

Dose / conc.:

5 mg/kg bw/day (nominal)

Remarks:

Group 4 (intravenous)

Doses / concentrations 4

Dose / conc.:

5 mg/kg bw/day (nominal)

Remarks:

Group 5: 14 daily oral doses of non-radiolabelled test item; single oral dose of radiolabel on Day 15

No. of animals per sex per dose / concentration:

Groups 1-4: 4 males and 4 females per dosage group
Group 5 animals: 4 male and 4 female rats received 14-daily doses of 5 mg/kg non-radiolabeled X204558. On day 15, rats received a single dose of 5 mg/kg 14C-X204558.

Control animals:

no

Positive control reference chemical:

None (not required)

Details on study design:

- Dose selection rationale: The dose levels were based on previous toxicity studies. The high dose of 75 mg/kg bw was selected as a level comparable to another study conducted with X204558. The low dose of 5 mg/kg bw (7 mg/kg bw; 5 mg equivalence for Group 3) was selected to be 15-fold lower than the high dose.
- Rationale for animal assignment (if not random): Animals were stratified by body weight and/or patency of their cannulae, and then randomly assigned to treatment groups

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : urine and cage washes, faeces, expired volatiles, expired CO2, blood and plasma, tissues
- Time and frequency of sampling:
Urine: All urine voided after administration of radiolabeled test material during the study was collected in dry-ice cooled traps. The urine traps were changed at 12, 24 and 48 hours post-dosing followed by 24-hour intervals for the remainder of the study. The cages were rinsed with water at the time the traps were changed and the rinse collected. Each urine specimen and urine/cage rinse was weighed, and a weighed aliquot of each sample analyzed for radioactivity by LSS as described below. Equal volume aliquots of urine samples (per time, dose and sex) from the 0-12-hour, 12- 24-hour and 24-48-hour collection intervals were pooled and stored at -80 ºC and selected urine samples underwent chemical analysis.
Following the terminal sacrifice of the animals, a final cage wash (FCW) was performed with water and detergent. The final cage wash and contents were collected and the weight of the sample was determined. The FCWand contents were shaken for > 4 hours. A weighed aliquot of the final cage wash was analyzed for radioactivity by LSS.
Feces: Feces were collected in dry-ice chilled containers at 24-hour intervals. An aqueous homogenate (~ 25% w/w) was prepared (shaken for > 4 hours) and weighed aliquots of these homogenates were oxidized and quantitated for radioactivity by LSS. In addition, equal volume aliquots of fecal homogenates from each animal was taken from the 0-24-hour and 24-48-hour collection intervals and pooled (per dose and sex). These pooled samples were stored at -80 ºC and selected fecal samples underwent chemical analysis.
Expired Volatiles: Air was drawn through the cage at approximately 850 mL/minute. Upon exiting the cage, the air was passed through a charcoal trapping agent to trap expired volatiles. The charcoal traps were changed at 24-hour intervals. The charcoal was ground with a blender. Weighed aliquots of the charcoal was oxidized and analyzed for radioactivity by LSS. Because < 1% of the administered dose was detected in the charcoal trap during the preceding interval, the replacement traps were not analyzed for radioactivity. Because < 1% of the administered dose was detected in the charcoal traps in the first studied group (Group 2), charcoal traps were not used in the remainder of the study.
Expired CO2: Following the charcoal trap (described above) the expired air was passed through a solution of monoethanolamine:1-methoxy-2-propanol (3:7 v/v) to trap expired CO2 and analyzed for radioactivity by LSS. The CO2 traps in Group 2 were changed at 12-hour, 24-hour and 48-hour intervals. Because < 1% of the administered dose was detected in the CO2 trap in the 12, 24 or 48-hour intervals, the replacement traps were not analyzed for radioactivity. Because < 1% of the administered dose was detected in the CO2 traps of the first studied group (Group 2), CO2 traps were not used in the remainder of the study.
Blood and plasma: Group 1-4 blood samples were collected at 0.08, 0.17, 0.25, 0.5, 1, 2, 3, 6, 12, 24 hours post dosing and every 24 hours thereafter. Radioactivity was determined in appropriate aliquots of the plasma and RBC of each sample collected from each group. Blood collections were discontinued in animals where the jugular cannula became non-patent. Weighed aliquots of RBC were oxidized and the plasma and RBC analyzed for radioactivity by LSS.
Tissues: The following were collected at sacrifice: adrenal, bladder, blood (terminal), bone (femur), bone marrow (femur), brain, carcass (residual), fat (perirenal), GI tract (with contents), heart, kidney, liver, lung, lymph node, muscle (skeletal), ovary, pancreas, pituitary, plasma (terminal), RBC (red blood cells), skin, spleen, testis, thymus, thyroid, uterus.
The brain, carcass, GI tract with contents, kidney, liver, and testis were collected, homogenized (~ 33% homogenate), a weighed aliquot oxidized, and analyzed for radioactivity by LSS. Bone was solubilized and analyzed for radioactivity by LSS. Blood was centrifuged to obtain plasma and the plasma analyzed for radioactivity by LSS. RBC was oxidized and analyzed for radioactivity by LSS. The skin was removed from the carcass and a representative skin sample oxidized and analyzed for radioactivity by LSS. The remaining tissues were directly oxidized without homogenization and analyzed for radioactivity by LSS.
Blood was obtained at sacrifice via cardiac puncture. The blood was centrifuged to obtain plasma and RBC and analyzed for radioactivity via LSS.

METABOLITE CHARACTERISATION STUDIES
Metabolite Profiles: Pooled samples (Groups 1-5; urine and feces) from selected intervals were analyzed (1 analysis per sample) via high performance liquid chromatography (HPLC) separation with in-line radiochemical detection (RAM) or fraction collection and LSS. The 168 hour urine (Group 2) from animals 12A7137 (female) and 12A7116 (male) were used for analytical purposes, as their dpm (disintegrations per minute) level (59 and 79 respectively) was near background (30 dpm). Control urine was needed for analysis after the high dose (Group 2) and since control urine wasn’t available at that time, a small sample from this male and female rat was used to get some preliminary information.
Metabolite Identification: Representative urine samples and fecal homogenate extracts were analyzed by HPLC with electrospray ionization and accurate mass quadrupole/time-of-flight mass spectrometry detection (LC/ESI-QTOF/MS) to identify metabolites.

Statistics:

Descriptive statistics were used, i.e., mean ± standard deviation. All calculations in the database were conducted using Microsoft Excel spreadsheets and databases in full precision mode (15 digits of accuracy). Certain pharmacokinetic parameters were calculated for plasma and urine data, including AUC (area-under-the-curve), Cmax, ½Cmax, and elimination rate constants, using a pharmacokinetic computer modeling program. Pharmacokinetic analysis was performed using PK Solutions.

Results and discussion

Preliminary studies:

In a comparison study with male Wistar rats after single oral gavage doses of 14C-X204558 (35 mg/kg bw), the concentration of radioactivity in blood and plasma, kinetic parameters and 48 hour mass balance were determined. No treatment-related clinical signs were observed. Tmax in plasma and blood were determined to be 1 hour post-dosing. The area under the concentration/time curve (AUC) was determined to be ~450 μg eq h g-1 (plasma) and 240 μg eq h g-1 (blood). Approximately 70% of the administered dose was recovered in urine (majority in the first 6 hours post-treatment), while ~20% was recovered in feces.

Main ADME results

Main ADME results 1

Type:

absorption

Results:

Orally administered X204558 was rapidly absorbed without any apparent lag time. The percent absorption of the orally administered dose of X204558 was 59-86%.

Main ADME results 2

Type:

excretion

Results:

The orally absorbed X204558 dose was rapidly excreted in urine (59-84% of the administered dose) without any difference between the sexes. A smaller percentage (16-42%) of the oral dose was eliminated in feces.

Main ADME results 3

Type:

excretion

Results:

The IV-administered test material was also rapidly excreted in urine (72-81% of administered dose). Only a small percent (12-17%) of the IV dose was eliminated in feces.

Main ADME results 4

Type:

distribution

Results:

Only 0.03-0.24% of the orally administered 14C-X204558 remained in the tissues after 168 hours (7 days) post-dosing. An average of 0.08-0.09% of the IV dosed 14C-X204558 remained in the tissues of the animals sacrificed 168 hours post-dosing.

Toxicokinetic / pharmacokinetic studies

Details on absorption:

A conservative estimate of absorption of the oral doses was made from the percent of administered radioactivity recovered in urine and rinse, final cage wash, CO2 and tissues at sacrifice. This estimate may be low, in that it does not account for net biliary elimination. Biliary elimination was determined in the IV dose group (as percent of dose eliminated in the feces) and added to the estimate of percent absorbed for the low oral dose groups (Groups 1 and 5). This could not be done for the high oral dose group due to apparent non-linear kinetics between the low and high dose groups. Low oral dose group animals (Groups 1 and 5) showed high absorption of X204558 (at least 72-84% of the administered dose), based on recovery in urine and non- GI tissues and bile (fecal data from IV group). Recovery of X204558 (Group 2; high dose) in the urine and non-GI tissues was similar (83-86% of the administered dose), despite lack of inclusion of biliary elimination for this group.

Details on distribution in tissues:

After 168 hours post-dosing, only a few tissues from animals of all groups contained quantifiable radioactivity (all tissues contained <0.3% of the administered dose and <0.8 μg/g tissue). No tissues were collected for female rat #7142, as it died some time after the 72 hour collection, due to an air hose disconnecting from the vacuum line.

- Tissue to Blood Ratios:
No tissue-toblood values could be calculated for Groups 1-4 (male and female) since all blood concentration levels were non-quantifiable. In Group 5, the tissue-to-blood ratios were highest in the bone marrow (11), Liver (6) and RBC (6) in the male rat, while skin (14), RBC (10) and liver (4) were highest in the female rat at 168 hours postdosing.
Group 1. Low Single Oral Dose (5 mg/kg bw) of 14C-X204558: On average, a total of 0.03% of the 5 mg/kg bw single oral dose of 14C-X204558 remained in the tissues 168 hours after dosing. Most was found in the liver, skin and GI tract (0.01% of the administered dose, each). The mean of all male and female tissues was below 0.016 μg-eq/g.
Group 2. High Single Oral Dose (75 mg/kg bw) of 14C-X204558: On average, a total of 0.03-0.24% of the 75 mg/kg bw single oral dose of 14CX204558 remained in tissues 168 hours after dosing. Consistent with that observed for low-dosed animals, the majority of the radioactivity was recovered in the residual liver, skin and GI tract (0.01-0.02% for liver and GI, and 0.01-0.22%, for skin). For males, the highest concentrations, expressed as μg 14C-X204558 equivalent/g of
tissue, ranked from liver (0.3 μg-eq/g) > GI tract (0.1 μg-eq/g) > skin (0.02 μg-eq/g). For females, skin (0.8 μg-eq/g) > Liver (0.14 μg-eq/g) > GI tract (0.10 μgeq/g).
Group 4. Low Single IV Dose (5 mg/kg bw) of 14C-X204558: On average, a total of 0.08-0.09% of the 5 mg/kg bw single IV dose of 14C-X204558 remained in tissues 168 hours after dosing, most of which was found in the skin. Tissue residue concentrations from the IV-dosed animals were highest in kidney, liver and skin tissue. The mean of male and female tissues was below 0.05 μg-eq/g.
Group 5. Low Multiple Oral Dose (5 mg/kg bw) of 14C-X204558: Tissue residue concentrations from the multiple-dosed animals followed a similar trend that was observed in single low-dosed animals. The mean of male and female tissues was below 0.03 μg-eq/g, with the highest concentrations in the bone marrow, skin and RBC.

- Time-course Concentration of Radioactivity and Pharmacokinetics in Plasma:
The 12 hour blood sample was not taken from 2 female rats (7131 and 7132) from Group 1 due to cannula issues resulting in excess blood loss. It was decided to minimize the stress to these animals by eliminating the 12 hour blood sample and to re-evaluate their health at 24 hours post-dosing.
Oral Doses of 14C-X204558: After an oral gavage of 5 mg/kg bw, the orally administered X204558 was rapidly absorbed without any apparent lag time and achieved the highest measured concentration (Cmax), on average, within 0.15 hours (tmax) and ½ Cmax was reached within 0.5 hours. After Tmax, plasma concentrations declined in a biphasic manner. The mean plasma alpha phase half-life (t½α) was between 0.3 and 0.4 hours for both male and female rats. The mean plasma beta phase halflife (t½β) was 10-17 hours. The AUC of radioactivity at 5 mg/kg bw oral dose was 4.2 ± 0.5 μg-hr/mL (male) and 5.0 ± 1.1 μg-hr/mL (female).
Similar to the low dose group (Group 1), the mean Tmax for the high dose group (Group 2) animals was ≤0.8 hours post-dosing. The mean Cmax of the high dose group was 16-fold higher than the low dose; only very slightly above the dose proportionality expected from the difference in the dose. Plasma levels of radioactivity declined in two distinct phases (α and β), similar to that observed for the low dose group animal. The mean t½β of 14C-X204558 derived radioactivity from plasma for Group 2 was 0.4-0.6 hours. The rate of decline of plasma radioactivity during the α phase for the Group 2 (high dose) was slightly slower than for Group 1 (low dose). The Group 2 plasma t½β was ~8-10 hours, similar to that of Group 1. The AUC of radioactivity at 75 mg/kg bw oral dose was 199 ± 20 μg-hr/mL (male) and 162 ± 25 μg-hr/mL (female), which was 32-47 fold higher than at the low dose of 5 mg/kg bw, inconsistent with the 15-fold difference between the two doses. This kinetic non-linearity is consistent with the apparent higher biliary elimination at the low dose.
IV Dose of 14C-X204558: The mean half-life of decline in plasma radioactivity was 0.3-0.4 hours for the rapid α phase and 23-33 hours for the slow β phase. The mean plasma AUC of radioactivity including all time-points after IV dosing was 3.0-3.3 μg-hr/mL. The mean plasma AUC of radioactivity including time-points through 48 hours after IV dosing was 2.8-3.0 μg-hr/mL. The mean total body clearance of the injected 14C-X204558-derived radioactivity was between 1595 and 1679 mL/hr/kg.

- Time-course Concentration of Radioactivity and Pharmacokinetics in RBC:
Oral Doses of 14C-X204558: The RBC concentrations of Groups 1 and 2 were lower than the plasma time-course concentration profiles. Due to the lack of quantifiable data-points after ~2 hours, an alpha and beta phase could not be determined. The mean calculated Cmax of radioactivity in RBC was 6-13-fold lower (Groups 1 and 2) than the levels found in plasma. The elimination t½ of the radioactivity from RBC was calculated to be 0.4 hours, on average (with the exception of data from one animal that was considered an outlier). As seen in the plasma, the AUC of radioactivity in the RBC was not dose-proportional between the low and high oral dose groups.
IV Dose of 14C-X204558: The alpha phase half-life of RBC radioactivity was 0.16 hours and the beta phase was 17 and 18 hours. The rate of clearance of X204558 from RBC was higher than that of the plasma.

Details on excretion:

- Urinary Elimination:
Group 1. Low Single Oral Dose (5 mg/kg bw) of 14C-X204558: Following a single oral dose of 14C-X204558, a mean total of 68 and 64% percent of the administered dose were recovered in urine and the rinse of male and female rats, respectively. Radioactivity was rapidly excreted with 96 and 95% of total urinary elimination occurring within 12 hours post-dosing for both males and females, respectively.
Group 2. High Single Oral Dose (75 mg/kg bw) of 14C-X204558: Mean urinary elimination of the high dose of 75 mg 14C-X204558/kg bw was 82 and 84% of the administered dose for the males and females, respectively. Radioactivity was eliminated in urine slightly later than the low dose, with 94 and 93% of total urinary elimination occurring within 12 hours post-dosing for males and females, respectively.
Group 4. Low Single IV Dose (5 mg/kg bw) of 14C-X204558: Mean recoveries of the radioactivity in the urine/rinse from the male and female IV dose group was 81 and 72% of the administered dose, respectively. The pattern of elimination of urinary radioactivity was consistent with the low dose single oral administration with 98 and 97% of total urinary elimination occurring within 12 hours post-dosing for males and females, respectively.
Group 5. Low Multiple Oral Dose (5 mg/kg bw) of 14C-X204558: Mean recoveries of the radioactivity in the urine/rinse from the male and female repeated-dose group was 59 and 67% of the administered dose, respectively. The pattern of elimination of urinary radioactivity was consistent with the low dose single oral administration with 96 and 97% of total urinary elimination occurring within 12 hours post-dosing for both male and female rats, respectively.

- Fecal Elimination:
A smaller percentage (compared to recovery in urine) of the orally administered 14CX204558 was eliminated in feces, ranging from an average of 16-34% of the administered dose after a single oral dose (of either 5 or 75 mg 14C-X204558/kg bw) to 32-42% after repeat dosing.
Group 1. Low Single Oral Dose (5 mg/kg bw) of 14C-X204558: Following a single oral dose of 5 mg/kg 14C-X204558, a mean total of 33 and 34% percent of the administered dose were recovered in the feces of male and female rats, respectively. Radioactivity was rapidly excreted with 89 and 92% of total fecal elimination occurring within 24 hours post-dosing for both males and females, respectively.
Group 2. High Single Oral Dose (75 mg/kg bw) of 14C-X204558: Mean fecal elimination of the high dose of 75 mg 14C-X204558/kg bw was 19 and 16% of the administered dose for the males and females, respectively. Radioactivity was eliminated slightly later than in the low dose group, with 85 and 86% of total fecal elimination occurring within 24 hours post-dosing for males and females, respectively.
Group 4. Low Single IV Dose (5 mg/kg bw) of 14C-X204558: Mean recoveries of the radioactivity in the feces from the male and female IV dose group were 12 and 17% of the administered dose, respectively. The majority of the fecal elimination (83 and 88% of total fecal elimination) occurred within 24 hours post-dosing for males and females, respectively. All fecal elimination in this group represents biliary excretion since the dose was administered intravenously.
Group 5. Low Multiple Oral Dose (5 mg/kg bw) of 14C-X204558:Mean recoveries of the radioactivity in the feces from the male and female repeated-dose group were 42 and 32% of the administered dose, respectively. Again, the majority (94 and 96%) of total fecal elimination occurred within 24 hours post-dosing for both male and female rats, respectively.

Toxicokinetic parameters

Toxicokinetic parameters 1

Toxicokinetic parameters:

Tmax: 0.148 h (5 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 2

Toxicokinetic parameters:

Tmax: 0.103 h (5 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 3

Toxicokinetic parameters:

Tmax: 0.750 h (75 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 4

Toxicokinetic parameters:

Tmax: 0.438 h (75 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 5

Toxicokinetic parameters:

Cmax: 7.096 μg/g (5 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 6

Toxicokinetic parameters:

Cmax: 9.081 μg/g (5 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 7

Toxicokinetic parameters:

Cmax: 113.696 μg/g (75 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 8

Toxicokinetic parameters:

Cmax: 134.634 μg/g (75 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 9

Toxicokinetic parameters:

other: t1/2 = 0.061 h, t½α = 0.297 h, t½β = 10.195 h (5 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 10

Toxicokinetic parameters:

other: t1/2 = 0.101 h, t½α = 0.381 h, t½β = 16.536 h (5 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 11

Toxicokinetic parameters:

other: t1/2 = 0.167 h, t½α = 0.618 h, t½β = 9.612 h (75 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 12

Toxicokinetic parameters:

other: t1/2 = 0.143 h, t½α = 0.363 h, t½β = 8.114 h (75 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 13

Toxicokinetic parameters:

other: t½α = 0.291 h, t½β = 23.418 h (5 mg/kg X204558 IV males)

Toxicokinetic parameters 14

Toxicokinetic parameters:

other: t½α = 0.406 h, t½β = 33.159 h (5 mg/kg X204558 IV females)

Toxicokinetic parameters 15

Toxicokinetic parameters:

AUC: 4.249 μg-hr/mL (5 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 16

Toxicokinetic parameters:

AUC: 5.041 μg-hr/mL (5 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 17

Toxicokinetic parameters:

AUC: 199.188 μg-hr/mL (75 mg/kg X204558 oral gavage males)

Toxicokinetic parameters 18

Toxicokinetic parameters:

AUC: 161.855 μg-hr/mL (75 mg/kg X204558 oral gavage females)

Toxicokinetic parameters 19

Toxicokinetic parameters:

AUC: AUC0-t = 3.315 μg-hr/mL, AUC0-48 = 3.055 μg-hr/mL (5 mg/kg X204558 IV males)

Toxicokinetic parameters 20

Toxicokinetic parameters:

AUC: AUC0-t = 3.026 μg-hr/mL, AUC0-48 = 2.753 μg-hr/mL (5 mg/kg X204558 IV females)

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

A total of two radiochemical peaks were detected in the urine samples across the profiles of all 5 groups and a total of one radiochemical peak was detected in the fecal homogenate extracts across the profiles of all 5 groups. Parent X204558 was detected in the urine samples as well as the fecal homogenate extracts. The most abundant peak in the urine and fecal homogenate extract from groups 1-5 was positively identified as X204558. The remaining peak in the urine radiochemical profiles accounted for < 1.6% of the radiolabeled administered dose in the rats, which has been tentatively identified as the acyl glucuronide conjugate of X204558.

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:

Absolute oral bioavailability of X204558 was also determined by comparing the dose-corrected AUC ratio of plasma radiotracer concentrations from the low-dose oral (Group 1) versus IV (Group 4) dose groups. The systemic bioavailability was estimated to be >100% (131%); it was concluded that systemic bioavailability was 100% for both male and female rats.

Any other information on results incl. tables

Dose Suspension (Oral) or Solution (IV) (Concentration, Stability, Administration and Recovery of the Dose)

The measured concentration of total test material in each dose suspension was 81-122% of the target concentration. The homogeneity results were 0.4-2.8% relative standard deviation for all groups. The concentration of radioactivity in each of the dose suspensions was 45-99% of the target concentration. This was deemed to have no impact on the overall interpretation of the study.

X204558 was determined to be stable in 0.5% METHOCEL™ for at least 15 days at a concentration of 0.98 mg/g.

The mean dose of 14C-X204558 administered to various groups was from 5.24-5.91 mg/kg bw for the targeted 5 mg/kg dose and 72.6-72.8 mg/kg bw for the targeted 75 mg/kg dose. The Group 5 rats administered the repeated dose received 14-daily doses of ~5 mg unlabeled X204558/kg bw prior to receiving 5.56-5.60 mg/kg bw 14C-X204558.

A mean range of 226-395 μCi/kg was administered to male and female rats for all dose groups. The actual radioactivity administered to rats through oral or IV dosing was 90- 158% with the targeted dose range of ~250 μCi/kg. The difference between the target and actual doses administered had no effects on the results of this study. There were no signs of toxicity observed in any animals following oral administration of either 5 or 75 mg 14C-X204558/kg bw.

Total recovery of radioactivity from all the animals averaged 98 ± 6% in the oral dose groups.

Applicant's summary and conclusion

Conclusions:

There was no bioaccumulation potential based on study results. Administered X204558 was rapidly and highly absorbed, poorly metabolized and readily eliminated in urine from the rat, with very low tissue residues.

Executive summary:

A pharmacokinetic and metabolism study (OECD 417) in F344/NTac rats study was conducted for 168 hours (7 days) post-dosing to determine absorption, distribution, metabolism, and excretion (ADME) of 14C-X204558 (cloquintocet acid) following oral (single or multiple dose of 5 mg/kg bw; single dose of 75 mg/kg bw), and intravenous (IV) exposure (single dose of 5 mg/kg bw).

Orally administered X204558 was rapidly absorbed without any apparent lag time. The percent absorption of the orally administered dose of X204558 in all three oral groups (single 5 mg/kg bw, multiple 5 mg/kg bw or single 75 mg/kg bw) was at least 59-86%, based on recovery in urine, non-GI tissues and expired air. Total recovery of radioactivity from all the animals averaged 99 and 92% in the oral and IV dose groups, respectively.

The orally absorbed X204558 dose was rapidly excreted in urine (59-84% of the administered dose) without any difference between the sexes. The majority of the urinary elimination (93-97%) occurred within the first 12 hours post-dosing. A smaller percentage (16-42%) of the oral dose was eliminated in feces.

The IV-administered test material was also rapidly excreted in urine (72-81% of administered dose). The majority of the urinary elimination (97-98%) occurred in the first 12 hours post-dosing. Only a small percent (12-17%) of the IV dose was eliminated in feces. Systemic bioavailability, calculated from the dose-corrected plasma AUC0-48h data for the low oral and IV dose groups, was 100% for both male and female rats.

Only 0.03-0.24% of the orally administered 14C-X204558 (low single, high single or multiple dose) remained in the tissues after 168 hours (7 days) post-dosing. An average of 0.08-0.09% of the IV dosed 14C-X204558 remained in the tissues of the animals sacrificed 168 hours post-dosing.

In the rats dosed orally with 14C-X204558, plasma radioactivity declined rapidly during the α phase (t½α = 0.3-0.6 hours) followed by relatively slow decline during the terminal ß phase (t½ ß = 8-17 hours). After IV administration, plasma radioactivity likewise declined rapidly during the α phase (t½α= 0.3-0.4 hours) followed by an even slower decline during the terminal ß phase (t½ ß = 23-33 hours). The X204558 Cmax was dose proportional between the low and high single oral dose groups. However, the total systemic exposure, as represented by the AUCs of radioactivity in plasma, was not dose proportional.

A total of two radiochemical peaks were detected in the urine samples across the profiles of all 5 groups and a total of one radiochemical peak was detected in the fecal homogenate extracts across the profiles of all 5 groups. Parent X204558 was detected in the urine samples as well as the fecal homogenate extracts. The most abundant peak in the urine and fecal homogenate extract from groups 1-5 was positively identified as X204558. The remaining peak in the urine radiochemical profiles accounted for < 1.6% of the radiolabeled administered dose in the rats, which has been tentatively identified as the acyl glucuronide conjugate of X204558.

In conclusion, administered X204558 was rapidly and highly absorbed, poorly metabolized and readily eliminated in urine from the rat, with very low tissue residues.