Even when handed information on whether each clopidogrel-treated patient was a poor metabolizer
of the drug, treating physicians usually did not switch them to a different antiplatelet drug, ticagrelor, that would be fully effective despite the patient's reduced-metabolizer status.
The findings of this case represent therapeutic failure of primaquine due to an allele mutation of CYP2D6 rendering the individual a poor metabolizer
. While primaquine remains the therapeutic treatment for P.
Genotyping revealed the subject has CYP2D6 (*4/* 5; 1 gene copy) and CYP2C19 (*2/*2) which corresponded to poor metabolizer
phenotype for both enzymes.
Currently in the USA, patients with a poor metabolizer
phenotype (*2/*2, *2/*3, and *3/*3) are advised to use drugs such as prasugrel and ticagrelor ; however, in Chile, information regarding the prevalence of CYP2C19 polymorphisms is still lacking.
Moreover, only one admixed subject was a CYP2C9 predicted poor metabolizer
The activity of CYP2D6 is largely determined by genetic variability and common sequence variants exist in human populations that lead to poor metabolizer
(PM) phenotypes .
Four phenotypic categories have been assigned to individuals according to enzyme function: poor metabolizer
(PM), intermediate metabolizer (IM), extensive metabolizer (EM), and ultra-fast metabolizer (10,11).
When patients undergo pharmacogenetic testing, they are categorized into one of four phenotypes: ultra-rapid metabolizer (UM), extensive metabolizer (EM), intermediate metabolizer (IM), or poor metabolizer
([section]) BMI, body mass index; ([parallel]) EM, extensive metabolizer; ([paragraph]) PM, poor metabolizer
; (a) one patient in RA group refused the drug sensitivity test; (b) four patients (two in RAL group and two in RA group) refused the analysis of CYP2C19 polymorphism; * unpaired f-test; ** chi-square test.
The traditional assignment of phenotype is as follows: extensive metabolizer (EM), intermediate metabolizer (IM), poor metabolizer
(PM), and ultrarapid metabolizer (UM).
It has been shown that about 3% of Caucasians express the poor metabolizer
phenotypes S-mephenytoin, however literature review in this regards shows slight differences.