Benefits of Genetic Testing in Clopidogrel Patients
The tiniest features of different enzymes and membrane proteins, that take part in drug metabolism, are determined genetically. These features affect the function of these molecules which means that every one of us processes same drugs differently. Sometimes the difference between individuals is so huge that a certain basic dose of a drug – that works for many – does not work or provokes dangerous side effects for others. With pharmacogenetic testing it is possible to find out the individual response to certain drugs and ensure safe and efficient medication.
Clopidogrel is commonly used to prevent heart disease and stroke in Finland: it is prescribed annually to 52 000 Finns. Clopidogrel is an antiplatelet drug and its function is determined to a large extent by pharmacogenetics: it is metabolized through liver enzyme CYP2C19.
Function of CYP2C19 is determined by genome: around 30 % of Europeans are CYP2C19 poor or intermediate metabolizers, which means that the enzyme doesn’t function as wanted and clopidogrel will not be modified to an active substance. This results to inefficient treatment and can be predicted with pharmacogenetic testing.
GeneAccount Service examines around 20 genes that affect the metabolism of over 120 drug substances. Is it necessary or beneficial to test so many genes at once?
By testing multiple genes with the same test, it is possible to not only promote patient safety but create significant savings in health care costs. Only one genetic test is needed to find out the patient’s response to different drugs, which speeds up the planning of possible new medication in the future. For example, the GeneAccount Service’s gene panel includes genes CYP2D6 and SLCO1B1: the variations of these genes have an effect on many commonly prescribed drugs, just like in the case of CYP2C19 and clopidogrel.
According to Finnish prescription statistics from 2015 to 2017, approximately 30 % of clopidogrel patients were prescribed a drug, where knowing the function of liver enzyme CYP2D6 would have been beneficial. For example, 14 % of the clopidogrel patients have prescribed painkiller codeine and 7 % antidepressant amitriptyline.
“It is essential to know the pharmacogenetic features when prescribing new drugs to patients for efficient medication and lesser odds for side effects.”
Over 30 % of the patients were prescribed a cholesterol medicine simvastatin in addition to clopidogrel. Pharmacogenetic properties of liver protein SLCO1B1 determine the metabolism of simvastatin and can be examined using genetic testing.
At least knowing the features of these two genes, CYP2D6 and SLCO1B1, in addition to CYP2C19 is beneficial when prescribing clopidogrel to a patient.
If individual response to different drugs is not paid attention to, using multiple drugs at once may lead to series of side effects – which are often treated with new drugs. It is essential to know the pharmacogenetic features when prescribing new drugs to patients for efficient medication and lesser odds for side effects. When the genetic test is performed well before the planning of new medication, the extra costs for testing are minimal compared to hospitalizations and additional treatments that result from inefficient medication. Pharmacogenetic testing is also a powerful tool for finding the correct dosage of the drug, and it reduces the need for trial and error with different dosages and drugs thus improving the patient’s experience of the treatment.
Abomics assessed whether testing broad pharmacogenetic panel in clopidogrel patients is useful. Abomics examined how many of the clopidogrel patients were prescribed other drugs in which metabolism is affected by pharmacogenetic variation.
From Finnish prescription statistics, the data from 17 373 clopidogrel patients was examined and the amount of drugs metabolizing through CYP2D6 and SLCO1B1 was collected. The statistics were from 2015 to 2017 and provided by Multirec Ltd.
The text is based on the abstract “Selecting Pharmacogenetic Test for Clopidogrel Patients” (Jari Forsström, Milla Tulkki. 2018.).
More information on medication side effects at GeneAccount blog.