Utility of Plasma Drug Level Monitoring and CYP2C19 Genotyping in Dose Personalization of Escitalopram
Conditions: Depressive Disorder, Major
Sponsor: University of Belgrade

Utility of plasma drug level monitoring and CYP2C19 
genotyping in dose personalization of escitalopram therapy 
PsyCise_E 
Principal Investigator: Asst. Prof. Marin Jukić PhD 
Department of Physiology, Faculty of Pharmacy, University of Belgrade, Serbia 
Document Date: 12th January 2022 
 

Clinical trial protocol 
Test groups: 
PsyCise trial is designed to quantify changes in clinical outcomes in participants treated for 
depression using personalized antidepressant dosing regimen, based on therapeutic drug 
monitoring (TDM) and CYP2C19 genotyping; as compared to the standard, “one size fits all” 
dosing. In order to reach this goal, we have defined two test groups based on the TDM 
findings. Namely, all participants who enter the trial (Visit 0) will begin taking standard 
escitalopram dose of 10 mg/day for two weeks when their blood samples will be taken for 
the purpose of TDM, and based on their steady state escitalopram concentrations they will 
be allocated to one of two groups at week 4 of the trial (visit 1): 
1) “Standard dose” group: Participants will be allocated to this group if their TDM 
results at week 2 show their steady state escitalopram plasma concentrations were 
inside “therapeutic window” (25-50 ng/ml). For these participants, initial standard 
escitalopram dose of 10 mg/day is estimated to be optimal so they will continue to 
receive the same dose until the end of the trial at week 8 (visit 2). 
2) “Adjusted dose” group: If TDM results at week 2 suggest that participant taking 
standard dose is underdosed or overdosed, given participant is allocated to this 
group. New, personalized dosing regimen will be produced for this participants 
based on steady state escitalopram plasma concentrations measured at week 2, and 
they will receive personalized escitalopram dose from week 4 (visit 1) until the end 
of the trial at week 8 (visit 2). 
Course of the trial: 
Week 0 
Initial Visit (Visit 0 – V0) 
- 
Participant will be enrolled at this point if inclusion criteria are met. 
- 
Escitalopram monotherapy for Major Depressive Disorder in previously untreated 
patient will be initiated at standard dose of 10 mg/day. 
- 
Outcomes measured:  
1. General and socio-demographic information 
2. Clinical questionnaires 
3. Anthropometric measurements 
4. Cardiological assessment 
5. Serum samples for biochemical analyses 
6. Buffy coat samples for DNA extraction and CYP2C19 genotyping* 
(*Sample is not time dependent, it can be taken at any visit) 
Week 2 
Mid-Visit (Vk) 
- 
Escitalopram plasma concentrations reach steady state. 
- 
Plasma sample taken for the purpose of TDM and group allocation. 

- 
Percentages of participants who are underdosed and overdosed will be measured 
and used to confirm previous findings [Jukić 2018] 
Week 4 
Visit 1 (V1) 
- 
Participants are allocated to the “Standard dose” or “Adjusted dose” group 
- 
Independent clinician prescribes new dosing regimen to the participants in “Adjusted 
dose” group, and informs patients in “Standard dose” group to continue taking the 
same standard escitalopram dose. 
- 
Clinician who usually monitors given patient is unaware of the group patient is 
allocated to, or the dose prescribed to a patient at Visit 1. 
- 
Outcomes measured: 
1. Clinical questionnaires 
2. Anthropometric measurements 
3. Cardiological assessment 
4. Serum samples for biochemical analyses 
5. Plasma samples to reconfirm TDM findings in VK 
Week 8 
Visit 2 (V2) 
- 
Final visit of the trial and the end of the follow-up. 
- 
Outcomes measured: 
1. Clinical questionnaires 
2. Anthropometric measurements 
3. Cardiological assessment 
4. Serum samples for biochemical analyses 
5. Plasma samples to reconfirm TDM findings in VK and V1 for Standard dosing 
group, and to determine whether personalized dose is optimal for the 
patients in Personalized dosing group. 
If needed, alternative course will be used:  
Week 0 
Initial visit + Mid-visit (V0+k) 
- 
Participant on the stable (longer than 2 weeks) monotherapy of Major Depressive 
Disorder with standard dose of escitalopram (10 mg/day) will be enrolled if other 
inclusion criteria are met. 
- 
Outcomes measured:  
1. General and socio-demographic information 
2. Clinical questionnaires 
3. Anthropometric measurements 
4. Cardiological assessment 
5. Serum samples for biochemical analyses 
6. Plasma sample for the purpose of TDM and group allocation. 
7. Buffy coat samples for DNA extraction and CYP2C19 genotyping* 

(*Sample is not time dependent, it can be taken at any visit) 
Week 2 
Visit 1 (V1) – Identical to the standard protocol 
- 
Participants are allocated to the “Standard dosing” or “Personalized dosing” group 
- 
Independent clinician prescribes new dosing regimen to the participants in 
“Personalized dosing” group, and informs patients in “Standard dosing” group to 
continue taking the same standard escitalopram dose. 
- 
Clinician who usually monitors given patient is unaware of the group patient is 
allocated to, or the dose prescribed to a patient at Visit 1. 
- 
Outcomes measured: 
1. Clinical questionnaires 
2. Anthropometric measurements 
3. Cardiological assessment 
4. Serum samples for biochemical analyses 
5. Plasma samples to reconfirm TDM findings in Vk 
Week 6 
Visit 2 (V2) – Identical to the standard protocol  
- 
Final visit of the trial and the end of the follow-up. 
- 
Outcomes measured: 
1. Clinical questionnaires 
2. Anthropometric measurements 
3. Cardiological assessment 
4. Serum samples for biochemical analyses 
5. Plasma samples to reconfirm TDM findings in Vk and V1 for Standard dosing 
group, and to determine whether personalized dose is optimal for the 
patients in Personalized dosing group. 
Hypotheses: 
1) More than one quarter of participants will be overdosed or underdosed under 
standard escitalopram dosing regimen (10 mg/day), as determined by TDM data 2 
weeks after the beginning of the therapy.  
2) Participants with escitalopram steady state plasma concentration outside the 
therapeutic window (“Adjusted dose” group) will experience reduced efficacy and 
more severe side effects of escitalopram therapy before dose personalization (at V1) 
compared to the participants with escitalopram levels within therapeutic window 
(“Standard dose” group) at standard dosing. 
3) Participants with escitalopram steady state plasma concentration outside the 
therapeutic window (“Adjusted dose” group) will show improved efficacy and less 
severe side effects of escitalopram therapy after dose personalization (at V2) as 
compared to before (at V1), and will reach clinical outcomes comparable to the 
“Standard dose” group (at V2). 

4) Decisions on whether to use personalized or standard dosing, and how to adjust 
personalized dose based on TDM data could have been determined before the 
beginning of the treatment using predictive model which, besides other predictors 
also includes CYP2C19 genotyping data. 
 
 

Statistical Analysis Plan 
Primary outcomes: 
To assess the efficacy of the escitalopram therapy under different dosing regimens we will 
use 21-item Hamilton rating scale for depression (HAM-D). Depression severity score will be 
measured at baseline (V0), at week 4 (V1) and week 8 (V2) after the beginning of the 
treatment. Since there is the need to compare depression severity scores between two test 
groups as well as between the visits V1 and V2, mixed analysis of covariance (Mixed 
ANCOVA) will be used if all assumptions associated with ANCOVA are met. Variables will be 
assigned as follows: 
1. Dependent variable: Depression severity score measured by HAM-D scale 
2. Independent variable - Fixed factor: Test group (Personalized vs Standard dosing) 
3. Independent variable - Repeated measurements: Visit (Visit 1 vs Visit 2) 
4. Covariates: Baseline HAM-D score (V0), Childhood trauma questionnaire score at V0, 
Age, Sex (Male=0, Female=1), Smoking status (0=Non-smoker, 1=Smoker), Alcohol 
consumption (0=No, 1=Yes), Metabolic syndrome diagnosed using siMS score 
[Soldatović 2016] (0=No, Yes) 
Positive outcome: interaction between group and visit is significant (α=0.05) 
 
Besides using absolute HAM-D scores, we will also compare relative changes in HAM-D 
scores between V1 and V2 visits as another way to express the potential differences in 
therapy efficacy between the two test groups. If all needed assumptions are met, statistical 
test used will be analysis of covariance (ANCOVA) with variables assigned as follows: 
1. Dependent variable: Relative change in HAM-D score between visits V1 and V2 
calculated by formula: 
𝐻𝐴𝑀𝐷𝑉1 −𝐻𝐴𝑀𝐷𝑉2
𝐻𝐴𝑀𝐷𝑉1
 
2. Independent variable: Test group (Pesonalized dosing vs Standard dosing) 
3. Covariables: Baseline HAM-D score (V0), Childhood trauma questionnaire score at 
V0, Age, Sex (Male=0, Female=1), Smoking status (0=Non-smoker, 1=Smoker), 
Alcohol consumption (0=No, 1=Yes), Metabolic syndrome (0=No, Yes) 
Positive outcome: Test group is a significant factor (α=0.05) 
 
 
 

Other primary outcome we will use to quantify changes in clinical outcomes between test 
groups will be severity of the treatment side effects measured using clinician reported UKU 
(Udvalg for Kliniske Undersogelser) side effect rating scale.  UKU scale rates 48 potential 
adverse reactions with intensity score ranging from 0 to 3 where score 3 signifies maximal 
intensity and score 0 signifies absence of the adverse rection. Adverse drug reaction 
intensity scores for all 48 adverse reactions monitored with UKU scale will be measured at 
weeks 4 (V1) and 8 (V2) after the initiation of the escitalopram therapy.  Due to large 
number of comparisons, significance measures will be adjusted using False Discovery Rate 
(FDR) correction. Absolute values of all 48 Adverse reaction scores will be compared 
between test groups and between two time points using mixed model analysis of covariance 
(Mixed ANCOVA) where variables will be assigned as follows: 
1. Dependent variable: Adverse drug reaction score for the given adverse reaction 
measured by UKU scale 
2. Independent variable - Fixed factor: Test group (Personalized vs Standard dosing) 
3. Independent variable - Repeated measurements: Visit (Visit 1 vs Visit 2) 
4. Covariables: Age, Sex (Male=0, Female=1), Smoking status (0=Non-smoker, 
1=Smoker), Alcohol consumption (0=No, 1=Yes), Coffee consumption (0=No, 1=Yes), 
Use of psychoactive substances (0=No, 1=Yes), Metabolic syndrome (0=No, Yes), 
Creatinine clearance, AST/ALT ratio. 
Positive outcome: interaction between group and visit is significant (α=0.05) 
Alternatively, proportions of patients with intensity score greater than 0 (UKU scale 
intensity score >0 signifies the presence of the given adverse reaction) will be compared 
between the groups for all 48 adverse effect monitored with UKU scale at two time points: 4 
weeks after the enrolment (V1) and 8 weeks after the enrolment (V2). Due to large number 
of comparisons, significance measures will be adjusted using False Discovery Rate (FDR) 
correction. Proportion of individuals in two test groups affected with the given adverse 
reaction will be compared using binary logistic regression analysis separately for visit V1 and 
visit V2 as follows: 
1. Dependent variable: Frequency of the individuals affected with the given adverse 
drug reaction measured by UKU scale 
2. Covariables: Test group (Personalized vs Standard dosing), Age, Sex (Male=0, 
Female=1), Smoking status (0=Non-smoker, 1=Smoker), Alcohol consumption (0=No, 
1=Yes), Coffee consumption (0=No, 1=Yes), Use of psychoactive substances (0=No, 
1=Yes), Metabolic syndrome (0=No, Yes), Creatinine clearance, AST/ALT ratio. 
Positive outcome: Test group is a significant factor (α=0.05) 
 

Secondary outcomes: 
Retrospective TDM data on 2087 patients taking escitalopram [Jukić 2018] suggests that, in 
the clinical setting, about 40% of patients are expected to have their plasma escitalopram 
concentrations under the lower limit of the therapeutic window (25 ng/ml), and for about 
10% of patients we expect to have plasma escitalopram levels above the upper limit of the 
therapeutic window (50 ng/ml). One of our aims is to try to confirm these findings using 
prospective study design which allows for the better control of the confounding factors 
compared to the retrospective data. Number of the patients with plasma escitalopram 
levels outside the therapeutic window under standard dosing regimen (10 mg/day) will be 
assessed using TDM data at Mid-Visit (VK), 2 weeks after the beginning of the therapy. 
Big disadvantage of TDM guided establishment of the optimal drug exposure in the given 
patient is that it takes 4 weeks to personalize escitalopram dose and 2 more weeks to 
achieve optimal steady state drug concentrations. Alternative approach would be to build 
model that could predict optimal dose for every patient even before the initiation of the 
treatment. This model would have to include patient data on factors that could impact 
escitalopram exposure such as body weight, liver and kidney functions and genotype for the 
CYP2C19 gene which is responsible for the interindividual variability in the rate of 
escitalopram metabolism in liver [Jukić 2018]. After all participants have finished the trial we 
will retrospectively build model using data collected during the trial, and then validate our 
model comparing it to the TDM method of dose personalization. For this purpose, all 
patients will be genotyped for CYP2C19 gene and divided into 4 groups based on the 
enzymatic capacity of CYP2C19 enzyme: 
1. Poor metabolizer (PM): Carries *2/*2, *2/*3 or *3/*3 CYP2C19 genotype.  Almost 
absent CYP2C19 enzyme activity 
2. Intermediate metabolizer (IM): Carries *1/*2 or *1/*3 CYP2C19 genotype. Reduced 
CYP2C19 enzyme activity 
3. Normal metabolizer (NM): Carries *1/*1 CYP2C19 genotype. Normal CYP2C19 
enzyme activity 
4. Ultra rapid metabolizer: Carries *1/*17 or *17/*17 CYP2C19 genotype. Increased 
CYP2C19 enzyme activity 
Multiple linear regression model will be build using selected variables: 
1. Dependent variable: Plasma escitalopram concentrations at Week 2 (Vk) after the 
initiation of the treatment 
2. Independent variables: Body mass index, PM status (0=Yes, 1=No), IM status (0=Yes, 
1=No), NM status (0=Yes, 1=No), UM status (0=Yes, 1=No), Creatinine clearance, 
AST/ALT ratio 
 
 

Other outcome measures/observations: 
To further validate our primary outcome measures: escitalopram treatment efficacy and 
severity of adverse effects, we will use Clinical Global Impression (CGI) scales. Scores will be 
determined for all 3 CGI scales: for Severity of illness (CGI-S) scale at baseline, visit 1 and 
visit 2, and for Global improvement (CGI-I) scale and for Efficacy Index (CGI-E) at visits 1 and 
2. Differences in all 3 CGI scales between visits 1 and 2 will be compared between test 
groups separately using ANCOVA tests with the equivalent sets of covariates to the ones 
used for HAM-D scale. 
In all patients at baseline and at visits 1 and 2, electrocardiography will be performed in 
order to monitor potential QT interval prolongation. We will test for correlation between QT 
interval length and escitalopram plasma levels at various visits, and also we will compare 
changes in QT interval length between visit 1 and visit 2 in both test groups using mixed 
ANCOVA test adjusting for the baseline QT length. 
Due to high comorbidity of anxiety and depression, and since escitalopram is frequently 
prescribed in anxiety disorders, we will explore severity of anxiety symptoms in all 
participants at baseline (V0), Week 4 (V1) and Week 8 (V2) of the treatment by using 
clinician reported Hamilton anxiety rating scale (HAM-A). Severity of anxiety symptoms will 
be compared between two test groups at two time points (V1 and V2) using mixed analysis 
of covariance (Mixed ANCOVA). Variables to be considered as covariates will be: Baseline 
HAM-A score (V0), Childhood trauma questionnaire score at V0, Age, Sex (Male=0, 
Female=1), Smoking status (0=Non-smoker, 1=Smoker), Alcohol consumption (0=No, 1=Yes), 
Metabolic syndrome (0=No, Yes).  
Alongside with HAM-A scale we will also use serum cortisol levels as a biomarker for anxiety 
disorders in our population. Cortisol levels will be analyzed in a similar way to HAM-D and 
HAM-A scores using mixed analysis of covariance (Mixed ANCOVA) with covariates being: 
Baseline Cortisol serum levels (V0), Childhood trauma questionnaire score at V0, Age, Sex 
(Male=0, Female=1), Smoking status (0=Non-smoker, 1=Smoker), Alcohol consumption 
(0=No, 1=Yes), Metabolic syndrome (0=No, Yes). Additionally, correlation between HAM-A 
score and cortisol levels will be tested. 
Since stress, trauma and socio-economic status can all be a part of depressive disorder 
pathogenesis, we will explore these environmental factors in order to determine their role 
in the clinical pictures of our participants. Outcome measures used will be: 
1. Perceived stress score measured at baseline, visit 1 and visit 2,  
2. Childhood trauma score measured at baseline,  
3. Employment status (1=Unemployed, 2=Employed; monthly incomes <40 000 RSD, 
3=Employed; monthly incomes 40 000-80 000 RSD, 4=Employed; monthly incomes 
>80 000RSD).  
4. Marital status (1=Unmarried, 2=Married, 3=Divorced, 4=Widowed) 
5. Education level (1=Primary education (8 years), 2= High school diploma (8+3 or 8+4 
years),  3= Associate’s degree (8+4+2 or 8+4+3 years) 4= Bachelor’s degree (8+4+4 
years or higher) 

We will separately test for the correlation between these variables and HAM-D score, HAM-
A score and CGI-S score.