TITLE:
Is Dosage Adjustment for Olanzapine Really Necessary?
AUTHORS:
Kelvin N. Christie
KEYWORDS:
Schizophrenia, Kidney, Liver, Olanzapine (OLZ)
JOURNAL NAME:
Open Journal of Psychiatry,
Vol.13 No.3,
July
21,
2023
ABSTRACT: Schizophrenia is a prevalent and disabling disorder, commonly treated with
medications such as clozapine and olanzapine. However, long-term side effects and
limitations of these drugs, coupled with treatment resistance in a significant proportion
of patients, necessitate alternative strategies. Furthermore, individuals with schizophrenia
are at an increased risk of developing kidney and liver diseases, which may be influenced
by cardiovascular comorbidities and shared genetic markers. Considering the use
of olanzapine in patients with severe liver or
kidney diseases requires careful evaluation. Although these organs play crucial
roles in olanzapine excretion and metabolism, current pharmacological research suggests
that dosage adjustment may not be necessary even in the presence of severe organ
disease. Olanzapine acts on D2 and 5HT2A receptors, alleviating both positive and
negative symptoms of schizophrenia. However, the metabolism and clearance of olanzapine
exhibit substantial inter-individual variability influenced by factors such as gender, age, ethnicity, smoking habits, and co-medication.
Additionally, olanzapine may induce unwanted side effects, including prolactin
release, metabolic dysregulation, and liver-related complications. The present study
aims to investigate whether dosage adjustment of olanzapine is necessary for individuals
with comorbid moderate liver and severe kidney disease. While the study remains ongoing, preliminary findings using a pharmacokinetic
model predict that dosage adjustment may not be required in these patients. The
expected olanzapine plasma concentration in individuals with both conditions
is estimated to be 18.14ng/ml, which is considerably below the identified toxic
dosage threshold of 100ng/ml. However, further investigations are warranted to validate the findings and establish definitive guidelines
and personalize treatment strategies for individuals with both liver and
kidney disease.