# Imaging the impact of sex and age on OATP function in humans: Consequences for whole-body pharmacokinetics and liver exposure

Solène Marie, Anne-Lise Lecoq, Louise Breuil, Fabien Caillé, Vincent Lebon, Claude Comtat, Sébastien Goutal, Laurent Becquemont, Michel Bottlaender, Céline Verstuyft, et al.

► To cite this version:

Solène Marie, Anne-Lise Lecoq, Louise Breuil, Fabien Caillé, Vincent Lebon, et al. Imaging the impact of sex and age on OATP function in humans: Consequences for whole-body pharmacokinetics and liver exposure. Acta Pharmaceutica Sinica B, 2025, 15 (5), pp.2736 - 2745. 10.1016/j.apsb.2025.03.030. cea-05273817

HAL Id: cea-05273817

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Submitted on 23 Sep 2025

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ORIGINAL ARTICLE

# Imaging the impact of sex and age on OATP function in humans: Consequences for whole-body pharmacokinetics and liver exposure

Solène Marie<sup>a,b,c,*</sup>, Anne-Lise Lecoq<sup>d</sup>, Louise Breuil<sup>a</sup>, Fabien Caillé<sup>a</sup>, Vincent Lebon<sup>a</sup>, Claude Comtat<sup>a</sup>, Sébastien Goutal<sup>a</sup>, Laurent Becquemont<sup>d,e</sup>, Michel Bottlaender<sup>a</sup>, Céline Verstuyft<sup>e,f</sup>, Nicolas Tournier<sup>a,*</sup>

Received 18 September 2024; received in revised form 28 December 2024; accepted 15 January 2025

KEY WORDS

Liver exposure;
Imaging;
Drug transporter;
Drug–drug interaction;
Drug-induced liver injury;
Pharmacokinetics;
Solute carrier;
Gender

**Abstract** Organic anion-transporting polypeptides (OATP) transporter function, which mediates many drugs' liver uptake, was investigated as a molecular determinant of pharmacokinetic variability. Whole-body PET imaging using ¹¹C-glyburide, a metabolically stable OATP probe, was performed in 16 healthy humans. Ten subjects underwent another ¹¹C-glyburide PET acquisition after OATP inhibition using rifampicin. Subjects were sorted according to age and sex: males<30y (24.0 ± 3.2 y, *n* = 7), males>50y (57.5 ± 5.6 y, *n* = 4), and females>50y (60.6 ± 2.4 y, *n* = 5). The blood-to-liver transfer rate (*k*<sub>uptake</sub>) was estimated to describe OATP function. Rifampicin decreased *k*<sub>uptake</sub> (−73 ± 13%, *P* < 0.001) and liver exposure (−50 ± 10%, *P* < 0.001) while increasing exposure in blood (+24 ± 24%, *P* < 0.01), myocardium, spleen, and brain (*P* < 0.05). No evidence of extra-hepatic rifampicin-inhibitable transport of ¹¹C-glyburide was found. Baseline liver exposure was 42.6 ± 18.4% higher (*P* < 0.05) in females>50y compared with males>50 y, consistent with higher *k*<sub>uptake</sub> values (*P* < 0.05), with negligible impact on blood exposure

<footnote><sup>a</sup>Université Paris-Saclay, CEA, Inserm, CNRS, BioMaps, Service Hospitalier Frédéric Joliot, Orsay 91401, France</footnote>

<footnote><sup>b</sup>Département de Pharmacie Clinique, Faculté de Pharmacie, Université Paris-Saclay, Orsay 91400, France</footnote>

<footnote><sup>c</sup>AP-HP, Université Paris-Saclay, Hôpital Bicêtre, Pharmacie Clinique, Le Kremlin Bicêtre 94270, France</footnote>

<footnote><sup>d</sup>AP-HP, Université Paris-Saclay, Hôpital Bicêtre, Centre de Recherche Clinique, Le Kremlin Bicêtre 94270, France</footnote>

<footnote><sup>e</sup>CESP, MOODS Team, INSERM UMR 1018, Faculté de Médecine, Univ Paris-Saclay, Le Kremlin Bicêtre F-94275, France</footnote>

<footnote><sup>f</sup>AP-HP, Université Paris-Saclay, Hôpital Bicêtre, Service de génétique Moléculaire, Pharmacogénéétique et Hormonologie, Le Kremlin Bicêtre 94270, France</footnote>

<footnote>*Corresponding authors.</footnote>

<footnote>E-mail addresses: solene.marie@universite-paris-saclay.fr (Solène Marie), nicolas.tournier1@universite-paris-saclay.fr (Nicolas Tournier).</footnote>

<footnote>Peer review under the responsibility of Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences.</footnote>
(P < 0.05). In males, neither liver exposure, blood exposure, nor *k*<sub>uptake</sub> were affected by aging (P < 0.05). *k*<sub>uptake</sub> was positively and negatively correlated with liver (P < 0.01, R<sup>2</sup> = 0.78) and blood (P < 0.01, R<sup>2</sup> = 0.40) exposures respectively. The impact of OATP function (*k*<sub>uptake</sub>) on liver exposure was 4-fold more pronounced than on blood exposure. OATP function may thus drive important sex-related differences in liver exposure, which were not discernible through conventional blood-based pharmacokinetics.

© 2025 The Authors. Published by Elsevier B.V. on behalf of Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

# 1. Introduction

Population characteristics such as sex and aging may be associated with clinically significant differences in pharmacokinetics (PK), with consequences for drug efficacy and safety¹. Such pharmacokinetic variability is often observed at the latest stages of drug development and even once the investigated drug is on the market. Anticipating pharmacokinetic variability may help optimize dose regimens to improve drug efficacy and tolerance in the targeted populations. However, in most situations, the molecular determinants leading to PK variability associated with sex or aging remain largely unknown²,³. In this context, sex- or aging-related differences in the function of most known drug transporters remain to be clarified in humans⁴,⁵.

Transporters of the organic anion-transporting polypeptides family (OATP), also known as Solute Carrier (SLCO) transporters, are considered important for PK⁶,⁷. In particular, OATPs expressed by hepatocytes (OATP1B1, OATP1B3, and OATP2B1) are known to play a key role in the hepatobiliary elimination of many drugs by mediating their uptake by hepatocytes⁸,⁹. Inhibition of liver OATPs is associated with decreased hepatobiliary clearance and may lead to clinically significant drug—drug interactions (DDIs) between OATP substrates and inhibitors⁶. Studies have also demonstrated a clinically significant decrease in the clearance of OATP substrates such as statins, repaglinide, atrasentan, irinotecan, and many others⁶,¹⁰. Polymorphisms of SLCO genes, especially OATP1B1, were associated with this decrease; these results hold potentially significant consequences for toxicity¹¹. Some studies have focused on potential changes in OATP expression associated with sex and aging in liver samples from animals or humans⁵,¹²⁻¹⁴. It may nonetheless be hypothesized that changes in OATP function may account for the observed sex- or age-related PK variability in humans.

Clinical pharmacokinetic studies indirectly estimate the impact of changes in OATP function through changes in the plasma kinetics of the substrate drugs⁴,¹⁵. However, this approach cannot accurately predict the extent of changes in OATP function at the blood-liver level. Additionally, from a drug efficacy or toxicity perspective, the target tissue concentration rather than plasma concentration is the most relevant. Unfortunately, changes in plasma exposure cannot accurately predict changes in exposure of target/vulnerable organs¹⁶. This unknown particularly holds for liver exposure which may lead to drug-induced liver injury (DILI)¹⁷.

Hepatic OATP function can be non-invasively and quantitatively studied through ¹¹C-glyburide, a recently developed positron emission tomography (PET) probe¹⁸,¹⁹. ¹¹C-glyburide is predominantly transported by OATP1B1, which mediates its uptake from the blood to the liver²⁰,²¹. The clinical validation of ¹¹C-glyburide as a PET probe for OATP, conducted in healthy young males, showed its specificity and suitable sensitivity to detect changes in liver transport function¹⁸.

This study conducted whole-body dynamic (WB-4D) PET-MR (magnetic resonance) experiments using ¹¹C-glyburide to explore differences in OATP function associated with sex and aging. Liver OATP function and WBPK of ¹¹C-glyburide were compared in healthy males and females (>50y). Data obtained in males >50y were compared to those obtained in younger males (<30y) using the same method. All subjects were assessed for single nucleotide variants (SNVs) of SLCO genes to consider any difference in genetic polymorphism.¹⁰

# 2. Material and methods

## 2.1. Subjects and study design

The study protocol was approved by an Ethic Committee (CPP IDF5: 17041, Study registration EudraCT 2017-001703-69). Experiments were conducted with respect to the 1975 Declaration of Helsinki. All subjects had a first medical examination where the inclusion criteria were checked by the clinical investigator. A written informed consent was signed after the subjects received all information about the study. A blood sample was collected for pharmacogenetic analysis, to genotype the SLCO genes encoding for OATP transporters.

Twenty-four volunteers were included in the study. Eight of them could not participate in imaging sessions due to technical issues. The subjects were classified into three groups: males below 30 years old (M < 30 y, 24.0 ± 3.2 y, n = 7), males above 50 years old (M > 50 y, 57.5 ± 5.6 y, n = 4), and post-menopausal females above 50 years old (F > 50 y, 60.6 ± 2.4 y, n = 5). Details about the groups and the subjects are provided in Table 1. Previously reported validation of ¹¹C-glyburide for OATP imaging was performed with the data of the males <30y group¹⁸.

Imaging sessions were held on a single day. Baseline WB-4D PET acquisition started with intravenous (i.v.) bolus of ¹¹C-glyburide. When possible, at least 3 h later after the first acquisition, a second ¹¹C-glyburide WB-4D PET scan was performed after infusion of rifampicin, used as an inhibitor of OATP, as previously described¹⁸ (9 mg/kg diluted in glucose 5% perfused, within 45 min of ¹¹C-glyburide injection, Rifadin®, Sanofi-Aventis, Gentiilly, France). Sixteen volunteers underwent a baseline ¹¹C-glyburide WB-4D PET acquisition. Ten of them underwent a second WB-4D PET in the presence of OATP inhibition (n = 5, 1, and 4, respectively for M < 30 y, M > 50 y, and F > 50y).

## 2.2. Candidate genetic polymorphisms analysis

Methods for genotyping SLCO1A2 c.516A > C (rs11568563), SLCO1B1 c.521T > C (rs4149015), SLCO1B3*4 c.699G > A (rs7311358), SLCO2B1 ex5 c.601G > A (rs35199625), and
<table><caption>**Table 1** Characteristics of healthy volunteers undergoing ¹¹C-glyburide PET imaging. The wild-type genotypes are AA for *SLCO1A2*, TT for *SLCO1B1*, GG for *SLCO1B3*, GG for *SLCO2B1* ex5, and CC for *SLCO2B1* ex10. Homozygous allelic variants are highlighted in grey.</caption><thead><tr><th rowspan="2">Group</th><th rowspan="2">Volunteer number</th><th rowspan="2">Age (y)</th><th rowspan="2">Weight (kg)</th><th rowspan="2">Rifampicin scan</th><th colspan="5">Genotype</th></tr><tr><th>SLCO1A2<br>c.516A > C<br>(rs11568563)</th><th>SLCO1B1<br>c.521T > C<br>(rs4149015)</th><th>SLCO1B3<br>c.699G > A<br>(rs7311358)</th><th>SLCO2B1<br>ex5 c.601G > A<br>(rs35199625)</th><th>SLCO2B1 ex10<br>c.1457C > T<br>(rs2306168)</th></tr></thead><tbody><tr><td rowspan="6">M &lt; 30 y</td><td>1</td><td>30.2</td><td>59</td><td>No</td><td>AA</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>2</td><td>24.7</td><td>73</td><td>Yes</td><td>AC</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>3</td><td>24.5</td><td>66</td><td>Yes</td><td>AA</td><td>CT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>4</td><td>22.2</td><td>81</td><td>Yes</td><td>AA</td><td>TT</td><td>GA</td><td>GG</td><td>TT</td></tr><tr><td>5</td><td>20.3</td><td>83</td><td>Yes</td><td>AC</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>6</td><td>21.4</td><td>61</td><td>No</td><td>AA</td><td>CT</td><td>GA</td><td>GG</td><td>CC</td></tr><tr><td rowspan="6">M &gt; 50 y</td><td>7</td><td>24.7</td><td>87</td><td>Yes</td><td>AA</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>8</td><td>59.3</td><td>81</td><td>No</td><td>AA</td><td>TT</td><td>AA</td><td>GG</td><td>TC</td></tr><tr><td>9</td><td>63.5</td><td>88</td><td>Yes</td><td>AA</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>10</td><td>57.8</td><td>74</td><td>No</td><td>AA</td><td>TT</td><td>GG</td><td>GG</td><td>CC</td></tr><tr><td>11</td><td>50.2</td><td>81</td><td>No</td><td>AA</td><td>CT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>12</td><td>59.6</td><td>66</td><td>Yes</td><td>AA</td><td>CC</td><td>GA</td><td>GG</td><td>CC</td></tr><tr><td rowspan="6">F &gt; 50 y</td><td>13</td><td>58.8</td><td>72</td><td>Yes</td><td>AA</td><td>CT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>14</td><td>58.8</td><td>67</td><td>Yes</td><td>AA</td><td>CT</td><td>AA</td><td>GG</td><td>CC</td></tr><tr><td>15</td><td>61.2</td><td>61</td><td>Yes</td><td>AA</td><td>CT</td><td>GA</td><td>GG</td><td>CC</td></tr><tr><td>16</td><td>64.6</td><td>53</td><td>No</td><td>AA</td><td>TT</td><td>AA</td><td>GG</td><td>CC</td></tr></tbody></table>

*SLCO2B1* ex10 c.1457C > T (rs2306168) are reported as supporting information.

## 2.3. PET acquisition

Pharmaceutical grade production of ¹¹C-glyburide, obtained using a previously reported method ²², is described as supporting information. WB-4D PET acquisitions were performed using a SIGNA® PET/MR scanner (GE Healthcare, Waukesha, WI, USA). The subjects were positioned on the patient bed, and MR localization acquisitions were performed. One venous catheter was inserted in each arm to inject ¹¹C-glyburide (1 min bolus) and blood sampling, respectively. Blood sampling was performed to i) determine the binding to plasma proteins before ¹¹C-glyburide injection (T = 0) ⁵⁷ and ii) assess the unchanged fraction of ¹¹C-glyburide in plasma (T = 0, 5, 10, 15, and 30 min after ¹¹C-glyburide injection, supporting information). The mean injected dose of ¹¹C-glyburide for baseline scans was 167 ± 56 MBq and 174 ± 53 MBq for the second scans. The mean specific radioactivity at the time of injection was 9.5 GBq/µmol and the corresponding mass of glyburide injected was 12.5 ± 6.2 µg. PET acquisition started with the injection of ¹¹C-glyburide. The first 3-min dynamic mono-bed acquisition was positioned on the abdomen (16 frames of 10 s), to capture uptake in the liver and some abdominal organs. This acquisition was immediately followed by repeated multi-bed whole-body acquisitions performed over the next 30 min (11 5-bed position acquisitions of 2.5 min, over a whole-body axial field-of-view of 25 cm).

## 2.4. PET data analysis

PET images were reconstructed using a 3D-iterative reconstruction algorithm, including resolution modeling and time-of-flight. Data was corrected for radioactive decay, attenuation, and random and scattered coincidences. Attenuation correction was based on a 2-point Dixon MR sequence (MRAC). Volumes of interest (VOIs) were delineated for tissues (liver, kidneys, spleen, myocardium,

pancreas, brain, and muscle) from PET and/or co-registered MRAC images using the PMOD® software (version 3.9, PMOD Technologies LLC, Zurich, Switzerland). An additional VOI was delineated which includes the left ventricle and the aorta to obtain an image-derived input function (IDIF). Validation of this method, performed in subjects of the males <30 y group, has already been reported and demonstrated a good correlation between IDIF and data from arterial blood sampling¹⁸. Urinary bladder was not investigated since our preliminary study using ¹¹C-glyburide demonstrated that radioactivity detected in urine almost exclusively corresponded to radiometabolites¹⁸.

Time-activity curves (TACs) were generated by calculating the mean radioactivity in these VOIs (kBq/cc). The TACs were expressed in standardized uptake values (SUV, unitless), generated by correcting the radioactivity in the VOIs for injected dose (kBq) and body weight (g). Areas under the TACs (AUC, expressed in SUV.min) were calculated from 0 to 30 min for each TAC to describe tissue exposure. Ratios between AUC in each tissue and arterial AUC estimated by IDIF ($K_p = AUC_{tissue}/AUC_{blood}$) were also calculated from 0 to 30 min to estimate tissue distribution.

The transfer constant ($k_{uptake}$) of ¹¹C-glyburide from blood to the liver was estimated using the integration plot analysis ²³,²⁴ from 5 to 30 min after ¹¹C-glyburide injection using Eq. (1):

$$ \frac{C_{\text{liver},t}}{C_{\text{blood},t}} = k_{\text{uptake}} \times \left( \frac{\text{AUC}_{\text{blood},0-t}}{C_{\text{blood},t}} \right) + V_E \quad (1) $$

where $C_{\text{liver},t}$ and $C_{\text{blood},t}$ represent the concentrations of ¹¹C-glyburide in the liver and blood (IDIF) respectively at time t. $AUC_{\text{blood},0-t}$ represents the area under the IDIF TAC from time 0 to t. $k_{\text{uptake}}$ corresponds to the slope of the linear regression plot. $V_E$ represents the initial distribution volume in the liver at time 0.

## 2.5. Data and statistical analysis

Data is reported as the mean ± SD (standard deviation). Differences between multiple groups were analyzed by a mixed-effect analysis followed by Tukey's multiple-comparison test.
The level of statistical significance was set to a *P*-value of less than 0.05. Linear regression and statistical comparisons were performed using GraphPad Prism® software (version 10.0, San Diego, CA, USA).

## 3. Results

### 3.1. Subjects and SLCO genotypes

Results of the genotyping of the genes encoding for OATP transporters are presented in Table 1. All subjects were wild-type carriers for the *SLCO2B1* ex5 (rs35199625) gene. Allelic variants were identified for all the other tested genes, with a range from one carrier of heterozygous mutation for *SLCO2B1* ex10 (rs2306168) to 6 mutated alleles for *SLCO1B1* (rs4149015). One subject carrier of the homozygous allelic variant was observed for the *SLCO2B1* ex10 (rs2306168, M < 30 y) and *SLCO1B1* (rs4149015, F > 50 y) genetic polymorphisms. Regarding the *SLCO1B3* (rs7311358, M > 50 y) polymorphism, 11 subjects were carriers of the c.699G > A mutation, which is predominant in Europe²⁵.

### 3.2. Metabolism and binding to plasma protein

$^{11}$C-glyburide was barely metabolized in both baseline and rifampicin conditions (Supporting Information Fig. S1). In all subjects, regardless of the presence or the absence of rifampicin, parent (unmetabolized) $^{11}$C-glyburide accounted for 90% or more of the plasma radioactivity during PET acquisition in the three groups of subjects. It was therefore decided not to correct blood data from radiometabolites given their limited impact on PET quantification. $^{11}$C-glyburide was highly bound to plasma proteins with a mean of 99.7 ± 0.6% in baseline condition and 99.3 ± 1.1% in rifampicin condition (Supporting Information Table S1), implying negligible impact of rifampicin on the free fraction of $^{11}$C-glyburide in plasma. Blood kinetics could therefore be described by the IDIF for kinetic modeling, as previously validated ¹⁸.

### 3.3. Liver and blood data

Representative PET images of the whole-body distribution obtained in each group display the predominant uptake of $^{11}$C-glyburide by the liver (Fig. 1). Liver uptake was visually reduced by OATP

<figure><img src="image_4.png" /><figcaption>**Figure 1** Whole-body PET images of $^{11}$C-glyburide distribution in baseline condition and after treatment with rifampicin (9 mg/kg i.v.) according to age and sex. Images are the maximum intensity projections of the frames summed from 0 to 30 min and are expressed in standardized uptake values (SUV).</figcaption></figure>
inhibition. Radioactivity in the circulation was obvious, probably reflecting the binding of ¹¹C-glyburide to plasma proteins.

The TACs presented in Fig. 2 confirm the high uptake of ¹¹C-glyburide by the liver. In baseline conditions, SUVmax liver was 18.8 ± 4.2 for M < 30 y, 16.4 ± 1.8 for M > 50 y, and 23.3 ± 3.2 for F > 50 y. AUCliver was similar in M > 50y compared to M < 30 y (-10.7 ± 8.8%, P > 0.05), suggesting a limited impact of aging on liver exposure (Fig. 3). However, liver exposure was significantly higher in F > 50y compared with age-matched males (M > 50 y, +42.6 ± 18.4%, Fig. 3). Changes in liver exposure did not translate into significant changes in blood exposure neither between M > 50 y versus F > 50 y, nor between M < 30 y and M > 50 y (Figs. 2 and 3). Significantly, higher liver exposure in females was also found when compared with pooled male data (M < 30 y + M > 50 y, n = 11, P < 0.001, Supporting Information Fig. S2). Only one subject belonging to the F > 50 y group presented the homozygous mutation on the SLCO1B1 gene (Table 1). She differed from the rest of the group in terms of blood exposure (AUCblood = 340 SUV.min vs 212 ± 26 SUV.min for the rest of the group, Fig. 3, Table S1) but not for the liver exposure (AUCliver = 544 SUV.min vs 572 ± 83 SUV.min for the rest of the group, Fig. 3, Table S1). Such behavior was not observed for subjects with either homozygous mutations of the SLCO1B3 (M > 50 y group), SLCO2B1 (M < 30 y group) genes, or heterozygous mutations of the investigated genes.

OATP inhibition using rifampicin drastically decreased liver exposure of ¹¹C-glyburide in all studied groups (-50 ± 10%, P < 0.001, Fig. 3, Table S1), which translated into a significant increase in blood exposure (+24 ± 24%, P < 0.01, Fig. 3,

Table S1). This trend was similarly observed across study groups. In the presence of rifampicin, levels of liver exposure were not different across study groups (P > 0.05, Fig. S2).

The $k_{uptake}$, which describes the blood-to-liver transfer of ¹¹C-glyburide, was significantly decreased by rifampicin (Fig. 3). The global magnitude of decrease in $k_{uptake}$ was -73 ± 13% (P < 0.001, n = 10). Low and similar $k_{uptake}$ values were obtained in the presence of rifampicin, with no significant difference between groups (P > 0.05, Fig. 3). Mean baseline $k_{uptake}$ in F > 50y (n = 5) was 45 ± 42% higher than that of M > 50 y, although non-significant when considering the entire group (n = 5, Fig. 3). However, statistical significance was reached (+60 ± 28%, P < 0.05, n = 4) when removing the subject with the homozygous mutation at the SLCO1B1 gene from the F > 50y group (Fig. 3). This result was confirmed when pooling together the male data (P < 0.05, Fig. S2). Importantly, the magnitude of decreased $k_{uptake}$ induced by rifampicin was strongly correlated with baseline $k_{uptake}$ (P < 0.001, R² = 0.95, Supporting Information Fig. S3), consistent with the negligible $k_{uptake}$ values of ¹¹C-glyburide in the presence of OATP inhibition.

When considering subjects of all 3 groups, in the presence and the absence of rifampicin, a significant and positive correlation was observed between $k_{uptake}$ and the liver exposure (P < 0.01, R² = 0.78, slope = 3937 SUV.min⁻², Fig. 4). A negative correlation was also observed between $k_{uptake}$ and blood exposure (P < 0.01, R² = 0.40, slope = -1036 SUV.min⁻², Fig. 4). This shows that OATP-mediated uptake governs both liver and blood exposures. However, the impact of OATP-mediated transport on liver exposure was ~4-fold higher than that on blood exposure.

<figure><img src="image_5.png" /><figcaption>**Figure 2** Time-activity curves of ¹¹C-glyburide in liver and blood (image-derived) in the baseline condition and after treatment with rifampicin (RIF, 9 mg/kg i.v.). Data is mean ± SD.</figcaption></figure>
<figure><img src="image_6.png" /></figure>

**Figure 3** Areas under the time activity curves (AUC, 0–30min) in liver and blood, transfer constants ($k_{uptake}$) from blood to liver, and $K_{p,liver}$ (AUC$_{liver}$/AUC$_{blood}$) of ¹¹C-glyburide. $k_{uptake}$ was assessed from integration plot analysis. White signs (and full bars) are used for baseline condition and red signs (and hatched bars) after treatment with rifampicin. The green signs indicate the subject with the homozygous mutation of the *SLCO1B1* gene. Data is mean ± SD. Statistical comparisons were performed using a mixed-effect analysis. The significance of the effect of rifampicin on the whole population is reported as ##$P < 0.01$ and ###$P < 0.001$. The Tukey's multiple-comparison test was performed with *$P < 0.05$, **$P < 0.01$, ***$P < 0.001$, and ns non-significant. **/**, ns/*, ns/ns show the outcome of comparison without or with the exclusion of the green sign subject.

<figure><img src="image_7.png" /></figure>

**Figure 4** Correlation between $k_{uptake}$ and the areas under the curves (AUCs) of ¹¹C-glyburide in liver and blood. Linear regression was used to test the correlation between liver or blood exposure and $k_{uptake}$.

### 3.4. WBPK of ¹¹C-glyburide

The $k_{uptake}$ could not be reliably estimated for most organs except the liver, probably due to low or extremely rapid uptake by these organs. The WBPK of ¹¹C-glyburide was therefore described by the tissue/plasma ratio ($K_{p,tissue}$ = AUC$_{tissue}$/AUC$_{blood}$). In addition to the liver ($K_p$ = 2.26 ± 0.23, Fig. 3), substantial uptake of ¹¹C-glyburide was observed in the kidneys ($K_p$ = 0.97 ± 0.06), pancreas ($K_p$ = 0.67 ± 0.09), myocardium ($K_p$ = 0.51 ± 0.02), and spleen ($K_p$ = 0.45 ± 0.04) (Fig. 5).

Consistent with liver $k_{uptake}$ values, rifampicin significantly decreased $K_{p,liver}$ (Fig. 3, Table S1). However, rifampicin did not impact $K_p$ in any other organ than the liver, suggesting the absence or limited impact of rifampicin-inhibitable transport (Fig. 5, Table S1). As a consequence of increased blood exposure (AUC$_{blood}$), rifampicin significantly increased tissue exposure (AUC$_{tissue}$) in some organs including the myocardium ($P < 0.05$), spleen ($P < 0.05$) and brain ($P < 0.001$, $n = 10$, Supporting Information Fig. S4).
<figure><img src="image_8.png" /><figcaption>**Figure 5** Ratios between AUC in each tissue and blood AUC ($K_{p,tissue}$ = AUC$_{tissue}$/AUC$_{blood}$, 0–30min). White signs (and full bars) are used for baseline condition and red signs (and hatched bars) after treatment with rifampicin. The green signs indicate the subject with the homozygous mutation of the *SLCO1B1* gene. Data is mean ± SD. Statistical comparisons were performed using a mixed-effect analysis. The significance of the effect of rifampicin on the whole population is reported as ns non-significant. The Tukey's multiple-comparison test was performed with \*P < 0.05 and ns non-significant. ns/ns shows the outcome of comparison without or with the exclusion of the green sign subject.</figcaption></figure>

## 4. Discussion

This study, performed in a cohort of healthy subjects of different sex and age, confirms that ¹¹C-glyburide benefits from metabolic stability, in either the presence or the absence of rifampicin¹⁸. *In vitro* hepatocyte experiments have shown that OATP-mediated uptake (predominantly by OATP1B1) accounts for 98% of the total liver uptake of glyburide, so the estimated proportion of metabolites in the liver is <10%²⁶. Different studies have also reported a higher affinity of glyburide for OATP1B1, with the lowest $K_m$ (1.2–2.0 µmol/L), compared to other OATPs (15–17 µmol/L and 6.3 µmol/L for OATP1B3 and OATP2B1 respectively)²⁷. More recently, it was estimated that OATP function accounts for 82% of the total liver uptake of glyburide (45% by OATP1B1, 26% by OATP1B3, and 11% by OATP2B1) using the proteomics-informed relative expression factor approach²¹. These results suggest that the PET signal predominantly reflects the parent (unmetabolized) compound so that the blood-to-liver transfer ($k_{uptake}$) can be reliably estimated for ¹¹C-glyburide, which is a major asset compared with previous PET probes²⁴,²⁸,²⁹. The dramatic decrease in $k_{uptake}$ precipitated by the OATP inhibitor rifampicin supports both the sensitivity of ¹¹C-glyburide to detect changes in OATP function and its specificity for OATP.

The strong correlation between individual $k_{uptake}$ values and corresponding liver or blood exposure suggests that liver OATP function, which occurs at the sinusoidal pole of hepatocytes ⁷, governs both the liver exposure and peripheral kinetics of ¹¹C-glyburide as a rate-determining factor. Therefore, our imaging data supports the relevance of the “extended clearance concept,”

which assumes that the transmembrane permeation process in elimination organs may predict the overall clearance of drugs ³⁰. Notably, the impact of change in $k_{uptake}$ on liver exposure was ~4-fold more pronounced than that on blood exposure. This result illustrates that estimation of OATP function by considering blood concentration of endogenous or exogenous probe substrates only ⁴,³¹ may considerably underestimate the impact of these transporters on liver exposure.

Two factors of variability in OATP function were investigated in this study. The most important result is the higher liver exposure observed in females compared with age-matched males after injection of the same dose of ¹¹C-glyburide. Higher liver exposure was linked to higher OATP function, as estimated by $k_{uptake}$. This outcome points to sex differences in liver exposure to drugs as a consequence of sex-related differences in OATP function. This *in vivo* result is consistent with the 1.3-fold higher expression of the *SLCO1B1* gene in females, measured in human samples ⁵,¹³. However, previous proteomic studies based on human liver samples obtained from a large cohort, did not show a significantly higher abundance of OATP1B1 in females compared with males, although considerable variability was observed ³²,³³. Western-blot analysis has previously revealed a trend toward a higher abundance of liver OATP transporters in females vs males. This cohort better matched the population of our study (56 ± 12 y, 7 males, 10 females), however, this trend was not statistically significant³⁴.

Our results suggest that sex-biased OATP function, which drives higher liver exposure in females, may account for the higher prevalence of DILI in females³⁵,³⁶. It was shown that females have a 1.5- to 1.7-fold greater risk of developing DILI and
the female/male ratio increases after the age of 49 years, suggesting a higher susceptibility to DILI after menopause³⁷. Unfortunately, ¹¹C-glyburide was not performed in young females for sex comparison in the young population.

Importantly, sex-related differences in OATP function—as well as liver exposure—could not be predicted from blood kinetics of ¹¹C-glyburide, even when excluding the subject with the homologous mutation of the *SLCO1B1* gene that shows particularly high baseline blood exposure compared with the rest of the group. Indeed, changes in blood exposure to ¹¹C-glyburide drastically underestimated changes in liver exposure. This observation is consistent with PK studies performed in larger cohorts that did not report any change in blood kinetics of glyburide between healthy males and females >60 y³⁸. Neither was the plasma kinetics of pravastatin, another OATP1B1 substrate, different between males and females³⁹⁻⁴¹.

Aging is the second factor of variability investigated in this study. The impact of normal aging on liver structure and function is well known, with a significant decrease in total liver volume, blood flow, and vascular volume⁴². The impact of age-related decline in renal function on drug clearance is also well established and allows for dose optimization in elderly patients⁴³. In contrast, the impact of aging on liver transport and metabolism remains unclear⁴³,⁴⁴. Our results do not support any significant impact of aging on liver OATP function, at least in males. Studies comparing the impact of aging on the plasma PK of OATP substrates are often inconclusive due to the frequent involvement of several other elimination pathways⁴. *Ex vivo* studies using proteomic or western-blot analysis reported no correlation between age and the abundance of OATP transporters³²⁻³⁴. We also found a limited impact of aging on blood or liver exposure to ¹¹C-glyburide, which is consistent with previous studies showing no or limited impact of aging on blood exposure to orally administered glyburide in either healthy subjects³⁸ or patients with type 2 diabetes⁴⁵. One of these studies reported a slower absorption in older subjects; however, the absorption phase could not be investigated in our study because ¹¹C-glyburide was i.v. administered. Moreover, studies reported a negligible impact of aging on the disposition of the OATP1B1 substrate pravastatin in the plasma of healthy subjects so dose adjustment in the older population is not required for this drug⁴⁰,⁴¹.

The liver perfusion of subjects included in this study has not been measured. However, age-related decline in liver perfusion is well established⁴⁶. Our results suggest that OATP function remains unaltered as the main parameter governing the hepatobiliary elimination of ¹¹C-glyburide in older males. This finding suggests that OATP-mediated elimination of ¹¹C-glyburide does not depend on liver blood flow or perfusion. From a PET imaging perspective, this may suggest that flow-limited passive diffusion of ¹¹C-glyburide, which can be estimated in the presence of rifampicin, has limited importance on the estimation of OATP function using this PET probe. Unfortunately, only one M > 50y underwent a second PET scan after complete OATP inhibition. However, the $k_{uptake}$ value for this subject was similar to that observed in the F > 50 y and M < 30 y groups.

The use of WB-4D PET acquisition enabled the study of WBPK of ¹¹C-glyburide. Imaging data shows a relatively low uptake of ¹¹C-glyburide in organs other than the liver. This low signal did not enable accurate quantification of ¹¹C-glyburide in some organs of small size, such as testis (data not shown). Importantly, the $K_p$ of ¹¹C-glyburide was not decreased in any investigated organ except the liver. This result suggests a liver-specific transport for this probe, consistent with the prime importance of OATP1B1, a liver-specific isoform, in mediating its

transport. As a consequence, ¹¹C-glyburide may lack sensitivity and/or specificity to detect extrahepatic OATP function mediated by OATP2B1 or OATP1A2, whose expression has been detected in other organs⁹. OATP inhibition increased the disposition of ¹¹C-glyburide in some organs as a result of enhanced blood exposure due to decreased liver uptake. Altogether, this PET data convincingly illustrates the impact of OATP-mediated DDI on WBPK in humans.

Some limitations exist in this study. Compared with traditional PK studies focusing on blood data, the total number of scanned subjects ($n = 16$ baseline scan, 10 rifampicin scan) is relatively small. This number, nonetheless, is higher than in previous PET imaging studies focusing on liver drug transporters²⁴,⁴⁷⁻⁴⁹. Rifampicin scans could not be performed in all the subjects, with only one rifampicin scan in the M > 50y group. Data obtained from 10 subjects belonging to the different groups who underwent both the baseline and post-rifampicin scans was amply sufficient to show the impact of rifampicin on liver function and WBPK. These results validate ¹¹C-glyburide PET imaging as a probe for OATP function. For most probes, drug transporter function is estimated by the magnitude of response to complete inhibition which requires two subsequent PET acquisitions²⁸,⁵⁰. However, the strong correlation between the baseline $k_{uptake}$ and rifampicin-precipitated decrease in $k_{uptake}$ suggests that a single baseline ¹¹C-glyburide PET scan is sufficient to estimate the total transport capacity of OATP, as previously reported ¹⁸ (Fig. S3). Our sample size ($n = 4–7$ subjects per group) was sufficient to reveal significant sex-related differences of significant pharmacokinetic importance in liver OATP function and exposure.

The impact of aging on OATP function was only investigated in males because females <30 y were not included. Hormonal regulation of OATPs has been reported⁵¹,⁵². The importance of hormonal changes during the menstrual cycle for pharmacokinetic variability should be considered⁵³. This consideration may complicate the interpretation of ¹¹C-glyburide PET data in pre-menopausal females. Moreover, effective contraception, which may also impact OATP function, is required to conduct PET studies in women of childbearing age. For these reasons, only post-menopausal women were included in our study. It should be noted that sex-related differences in OATP function and liver exposure were found in subjects >50 y, who correspond to the most medicated population, with an increased risk of DDI⁵⁴.

PET studies using dedicated probes may help untangle the pharmacokinetic importance of the genetic polymorphism of *SLCO* genes whose impact on transporter function has been reported²⁷,⁵⁵. Our study was not designed to address the impact of genetic polymorphism on OATP function using ¹¹C-glyburide PET imaging. Only one subject carrier of the well-characterized *SLCO1B1* no-function homozygous variant c.521 T > C (rs4149056) was scanned and differed from the rest of the group (F > 50 y). Other *SLCO1B3* and *SLCO2B1* genetic polymorphisms did not have such an effect in our cohort. However, ¹¹C-glyburide may lack the sensitivity to detect changes in OATP1B3 or OATP2B1 function, given its predominant transport by OATP1B1²⁶. Polymorphisms on the *SLCO1B1* gene have been classified as highly significant for PK by the *International Transporter Consortium*⁵⁶. Our data suggests that this polymorphism may have dramatic consequences for liver exposure. Further studies using ¹¹C-glyburide PET imaging, including a larger number of subjects selected upon *SLCO1B1* gene polymorphism, should be performed to quantitatively address the impact of this SNV on OATP function and the WBPK using ¹¹C-
glyburide PET imaging. Our results suggest that genetic polymorphism should be investigated separately in males and females.

## 5. Conclusions

WB-4D PET imaging revealed the tissue kinetics of ¹¹C-glyburide in humans. OATP inhibition using rifampicin showed the prime importance of hepatocyte OATP function in controlling liver and blood exposure, with consequences for WBPK. Our results suggest no significant decline in OATP function with aging. However, dramatically higher liver exposure was observed in females >50y compared with age-matched males, which was linked with greater OATP function. This sex difference was not discernible through conventional blood-based pharmacokinetics.

## Acknowledgments

This work was funded by grant ANR-16-CE17-0011 (France) and performed on a platform member of the France Life Imaging network (grant ANR-11-INBS-0006, France). The authors thank Maud Goislard and Philippe Gervais for their technical assistance.

## Author contributions

Solène Marie: Writing - review & editing, Writing - original draft, Visualization, Validation, Supervision, Project administration, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Anne-Lise Lecoq: Writing - review & editing, Validation, Resources, Project administration, Investigation, Data curation. Louise Breuil: Writing - review & editing, Methodology, Formal analysis, Data curation. Fabien Caillé: Writing - review & editing, Resources, Methodology. Vincent Lebon: Writing - review & editing, Resources, Methodology, Investigation, Funding acquisition. Claude Comtat: Writing - review & editing, Visualization, Software, Formal analysis, Data curation. Sébastien Goutal: Writing - review & editing, Visualization, Resources, Formal analysis, Data curation. Laurent Becquemont: Writing - review & editing, Validation, Project administration, Methodology, Investigation, Data curation, Conceptualization. Michel Bottlaender: Writing - review & editing, Visualization, Validation, Methodology, Investigation, Conceptualization. Céline Verstuyft: Writing - review & editing, Supervision, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Nicolas Tournier: Writing - review & editing, Writing - original draft, Visualization, Validation, Supervision, Resources, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization.

## Conflicts of interest

The authors have no conflicts of interest to declare.

## Appendix A. Supporting information

Supporting information to this article can be found online at https://doi.org/10.1016/j.apsb.2025.03.030.

## References

1. Soldin O, Mattison D. Sex differences in pharmacokinetics and pharmacodynamics. *Clin Pharmacokinet* 2009;**48**:143-57.

2. McLean A, Couteur D. Aging biology and geriatric clinical pharmacology. *Pharmacol Rev* 2004;**56**:163-84.

3. Koren G, Nordeng H, MacLeod S. Gender differences in drug bioequivalence: time to rethink practices. *Clin Pharmacol Ther* 2013;**93**:260-2.

4. Rattanacheeworn P, Kerr S, Kittanamongkolchai W, Townamchai N, Udomkarnjananun S, Praditpornsilpa K, et al. Quantification of CYP3A and drug transporters activity in healthy young, healthy elderly and chronic kidney disease elderly patients by a microdose cocktail approach. *Front Pharmacol* 2021;**12**:726669.

5. Yang L, Li Y, Hong H, Chang C, Guo L, Lyn-Cook B, et al. Sex differences in the expression of drug-metabolizing and transporter genes in human liver. *J Drug Metab Toxicol* 2012;**3**:1000119.

6. Giacomini KM, Huang S-M, Tweedie DJ, Benet LZ, Brouwer KLR, Chu X, et al. Membrane transporters in drug development. *Nat Rev Drug Discov* 2010;**9**:215-36.

7. Ciutà A, Nosol K, Kowal J, Mukherjee S, Ramírez A, Stieger B, et al. Structure of human drug transporters OATP1B1 and OATP1B3. *Nat Commun* 2023;**14**:5774.

8. Li Y, Meng Q, Yang M, Liu D, Hou X, Tang L, et al. Current trends in drug metabolism and pharmacokinetics. *Acta Pharm Sin B* 2019;**9**:1113-44.

9. Hagenbuch B, Stieger B. The SLCO (former SLC21) superfamily of transporters. *Mol Aspects Med* 2013;**34**:396.

10. Giacomini KM, Balimane PV, Cho SK, Eadon M, Edeki T, Hillgren KM, et al. International transporter consortium commentary on clinically important transporter polymorphisms. *Clin Pharmacol Ther* 2013;**94**:23-6.

11. The SEARCH Collaborative Group, Link E, Parish S, Armitage J, Bowman L, Heath S, et al. SLCO1B1 variants and statin-induced myopathy - a genomewide study. *N Engl J Med* 2008;**359**:789-99.

12. Hou W, Xu S, Zhu Q, Lu Y, Cheng X, Liu J. Age- and sex-related differences of organic anion-transporting polypeptide gene expression in livers of rats. *Toxicol Appl Pharmacol* 2014;**280**:370-7.

13. Liu J, Cui J, Lu Y, Corton J, Klaassen C. Sex-, age-, and race/ethnicity-dependent variations in drug-processing and NRF2-regulated genes in human livers. *Drug Metab Dispos* 2021;**49**:111-9.

14. Rost D, Kopplow K, Gehrke S, Mueller S, Friess H, Ittrich C, et al. Gender-specific expression of liver organic anion transporters in rat. *Eur J Clin Invest* 2005;**35**:635-43.

15. Zheng H, Huang Y, Frassetto L, Benet L. Elucidating Rifampin's inducing and inhibiting effects on glyburide pharmacokinetics and blood glucose in healthy volunteers: unmasking the differential effect of enzyme induction and transporter inhibition for a drug and its primary metabolite. *Clin Pharmacol Ther* 2009;**85**:78.

16. Rizk M, Zou L, Savic R, Dooley K. Importance of drug pharmacokinetics at the site of action. *Clin Transl Sci* 2017;**10**:133-42.

17. Segovia-Zafra A, Di Zeo-Sánchez D, López-Gómez C, Pérez-Valdés Z, García-Fuentes E, Andrade R, et al. Preclinical models of idiosyncratic drug-induced liver injury (iDILI): moving towards prediction. *Acta Pharm Sin B* 2021;**11**:3685-726.

18. Marie S, Breuil L, Chalampalakis Z, Becquemont L, Verstuyft C, Lecoq A, et al. [11C]glyburide PET imaging for quantitative determination of the importance of Organic Anion-Transporting Polypeptide transporter function in the human liver and whole-body. *Biomed Pharmacother* 2022;**156**:113994.

19. Tournier N, Saba W, Cisternino S, Peyronneau MA, Damont A, Goutal S, et al. Effects of selected OATP and/or ABC transporter inhibitors on the brain and whole-body distribution of glyburide. *AAPS J* 2013;**15**:1082-90.

20. Marie S, Frost K, Hau R, Martinez-Guerrero L, Izu J, Myers C, et al. Predicting disruptions to drug pharmacokinetics and the risk of
adverse drug reactions in non-alcoholic steatohepatitis patients. *Acta Pharm Sin* 2023; **13**:1-28.

21. Yin M, Balhara A, Marie S, Tournier N, Gáborik Z, Unadkat J. Successful prediction of human hepatic concentrations of transported drugs using the proteomics-informed relative expression factor approach. *Clin Pharmacol Ther* 2024; **115**:595-605.

22. Caillé F, Gervais P, Auvity S, Coulon C, Marie S, Tournier N, et al. Automated two-step manufacturing of [11C]glyburide radiopharmaceutical for PET imaging in humans. *Nucl Med Biol* 2020; **84-85**: 20-7.

23. Amor D, Goutal S, Marie S, F F, Bauer M, Langer O, et al. Impact of rifampicin-inhibitable transport on the liver distribution and tissue kinetics of erlotinib assessed with PET imaging in rats. *EJNMMI Res* 2018; **8**:81.

24. Takashima T, Kitamura S, Wada Y, Tanaka M, Shigihara Y, Ishii H, et al. PET imaging-based evaluation of hepatobiliary transport in humans with (15R)-11C-TIC-Me. *J Nucl Med* 2012; **53**:741-8.

25. Laitinen A, Niemi M. Frequencies of single-nucleotide polymorphisms of SLC01A2, SLC01B3 and SLC02B1 genes in a Finnish population. *Basic Clin Pharmacol Toxicol* 2011; **108**:9-13.

26. Li R, Bi Y, Vildhede A, Scialis R, Mathiagan S, Yang X, et al. Transporter-mediated disposition, clinical pharmacokinetics and cholestatic potential of glyburide and its primary active metabolites. *Drug Metab Dispos* 2017; **45**:737-47.

27. Nie Y, Yang J, Liu S, Sun R, Chen H, Long N, et al. Genetic polymorphisms of human hepatic OATPs: functional consequences and effect on drug pharmacokinetics. *Xenobiotica* 2020; **50**:297-317.

28. Tournier N, Stieger B, Langer O. Imaging techniques to study drug transporter function *in vivo*. *Pharmacol Ther* 2018; **189**:104-22.

29. Kaneko K, Tanaka M, Ishii A, Katayama Y, Nakaoka T, Irie S, et al. A clinical quantitative evaluation of hepatobiliary transport of [¹¹C] dehydropravastatin in humans using positron emission tomography. *Drug Metab Dispos* 2018; **46**:719-28.

30. Sugiyama Y, Aoki Y. A 20-year research overview: quantitative prediction of hepatic clearance using the *in vitro*-in vivo extrapolation approach based on physiologically based pharmacokinetic modeling and extended clearance concept. *Drug Metab Dispos* 2023; **51**:1067-76.

31. Momper J, Tsunoda S, Ma J. Evaluation of proposed *in vivo* probe substrates and inhibitors for phenotyping transporter activity in humans. *J Clin Pharmacol* 2016; **56**(S7):S82-98.

32. Prasad B, Evers R, Gupta A, Hop C, Salphati L, Shukla S, et al. Interindividual variability in hepatic organic anion-transporting polypeptides and p-glycoprotein (ABCB1) protein expression: quantification by liquid chromatography tandem mass spectroscopy and influence of genotype, age, and sex. *Drug Metab Dispos* 2014; **42**:78-88.

33. Burt HJ, Riedmaier AE, Harwood MD, Crewe HK, Gill KL, Neuhoff S. Abundance of hepatic transporters in caucasians: a meta-analysis. *Drug Metab Dispos* 2016; **44**:1550-61.

34. Taniguchi T, Zanetti-Yabur A, Wang P, Usyk M, Burk R, Wolkoff A. Interindividual diversity in expression of organic anion uptake transporters in normal and cirrhotic human liver. *Hepatol Commun* 2020; **4**:739-52.

35. Amacher D. Female gender as a susceptibility factor for drug-induced liver injury. *Hum Exp Toxicol* 2014; **33**:928-39.

36. Tong W, Shi Q, Salminen W, Chen M, Fang H, Suzuki A, et al. Unravelling sex differences in drug-induced liver injury. *Gen Appl Sys Toxicol* (eds B. Ballantyne, T.C. Marrs, T. Syversen, D.A. Casciano and S.C. Sahu) 2011. https://doi.org/10.1002/9780470744307.gat226.

37. Floreani A, Bizzaro D, Shalaby S, Taliani G, Burra P. Special interest group gender in hepatology of the Italian association for the study of the liver (AISF) sex disparity and drug-induced liver injury. *Dig Liver Dis* 2023; **55**:21-8.

38. Schwinghammer TL, Antal EJ, Kubacka RT, Hackimer ME, Johnston JM. Pharmacokinetics and pharmacodynamics of glyburide in young and elderly nondiabetic adults. *Clin Pharm* 1991; **10**:532-8.

39. Ho R, Choi L, Lee W, Mayo G, Schwarz U, Tirona R, et al. Effect of drug transporter genotypes on pravastatin disposition in European- and African-American participants. *Pharmacogenet Genomics* 2007; **17**: 647-56.

40. Pan H, Wacławski A, Funke P, Whigan D. Pharmacokinetics of pravastatin in elderly versus young men and women. *Ann Pharmacother* 1993; **27**:1029-33.

41. Sigurbjörnsson S, Kjartansdóttir T, Jóhannsson M, Kristinsson J, Sigurdsson G. A pharmacokinetic evaluation of pravastatin in middle-aged and elderly volunteers. *Eur J Drug Metab Pharmacokinet* 1998; **23**:13-8.

42. Kim H, Kisseleva T, Brenner D. Aging and liver disease. *Curr Opin Gastroenterol* 2015; **31**:184-91.

43. Drenth-van Maanen A, Wilting I, Jansen P. Prescribing medicines to older people—how to consider the impact of ageing on human organ and body functions. *Br J Clin Pharmacol* 2020; **86**:1921-30.

44. Soejima K, Sato H, Hisaka A. Age-related change in hepatic clearance inferred from multiple population pharmacokinetic studies: comparison with renal clearance and their associations with organ weight and blood flow. *Clin Pharmacokinet* 2022; **61**:295-305.

45. Jaber L, Antal E, Welshman I. Pharmacokinetics and pharmacodynamics of glyburide in young and elderly patients with non-insulin-dependent diabetes mellitus. *Ann Pharmacother* 1996; **30**:472-5.

46. Woodhouse K, Wynne H. Age-related changes in hepatic function. *Drugs Aging* 1992; **2**:243-55.

47. Bauer M, Matsuda A, Wulkersdorfer B, Philippe C, Traxl A, Özvegyl-Laczka C, et al. Influence of OATPs on hepatic disposition of erlotinib measured with positron emission tomography. *Clin Pharmacol Ther* 2018; **104**:139-47.

48. Gormsen LC, Sundelin E, Jensen J, Vendelbo M, Jakobsen S, Munk O, et al. In vivo imaging of human 11C-metformin in peripheral organs: dosimetry, biodistribution, and kinetic analyses. *J Nucl Med* 2016; **57**: 1920-6.

49. Billington S, Shoner S, Lee S, Clark-Snustad K, Pennington M, Lewis D, et al. PET imaging of [11C]rosuvastatin hepatic concentrations and hepatobiliary transport in humans in the absence and presence of cyclosporine A. *Clin Pharmacol Ther* 2019; **106**:1056-66.

50. Kusuhara H. Imaging in the study of membrane transporters. *Clin Pharmacol Ther* 2013; **94**:33-6.

51. Shchulkin A, Abalenikhina Y, Slepnev A, Rokunov E, Yakusheva E. The role of adopted orphan nuclear receptors in the regulation of an organic anion transporting polypeptide 1B1 (OATP1B1) under the action of sex hormones. *Curr Issues Mol Biol* 2023; **45**:9593-605.

52. Moscovitz J, Kalgutkar A, Nulick K, Johnson N, Lin Z, Goosen T, et al. Establishing transcriptional signatures to differentiate PXR-, CAR-, and AhR-mediated regulation of drug metabolism and transport genes in cryopreserved human hepatocytes. *J Pharmacol Exp Ther* 2018; **365**:262-71.

53. Kashuba A, Nafziger A. Physiological changes during the menstrual cycle and their effects on the pharmacokinetics and pharmacodynamics of drugs. *Clin Pharmacokinet* 1998; **34**:203-18.

54. Nobili A, Pasina L, Tettamanti M, Lucca U, Riva E, Marzona I, et al. Potentially severe drug interactions in elderly outpatients: results of an observational study of an administrative prescription database. *J Clin Pharmacol Ther* 2009; **34**:377-86.

55. Schulte R, Ho R. Organic anion transporting polypeptides: emerging roles in cancer pharmacology. *Mol Pharmacol* 2019; **95**:490-506.

56. Yee S, Brackman D, Ennis E, Sugiyama Y, Kamdem L, Blanchard R, et al. Influence of transporter polymorphisms on drug disposition and response: a perspective from the international transporter consortium. *Clin Pharmacol Ther* 2018; **104**:803-17.

57. Tournier N, Cisternino S, Peyronneau M, Goutal S, Dolle F, Scherrmann J, et al. Discrepancies in the P-glycoprotein-mediated transport of (18)F-MPPF: a pharmacokinetic study in mice and non-human primates. *Pharm Res* 2012; **29**:2468-76.