Research on heroin addicts has found that genetic variations within the study group resulted in different drug-treatment responses, a discovery that is being cited as crucial to improve future treatment programs by enhancing the accuracy of medication dosages needed by each particular patient, the National Health Research Institute (NHRI) said.
The research findings were presented at an international conference on the prevention and treatment of substance abuse held in Taipei on Thursday.
According to the NHRI, drug use and addiction can inflict great harm on society and damages personal health, with heroin use being one of the nation’s leading drug problems, with many addicts also using substances such as amphetamine, tobacco, alcohol and betel nut.
Methadone maintenance treatment, an opioid replacement therapy that aims to reduce or eliminate the use of illegal drugs, was launched in Taiwan in 2006 to fight opiate addiction.
During the conference, the NHRI’s Center for Neuropsychiatric Research associate research fellow Liu Yu-li (劉玉麗) and her group presented their research finding in pharmacogenomics, which is the study of drug treatment responses in subgroups of patients according to their genetic variants or genetic expression information.
She said that three liver cytochrome P-450 (CYP450) enzymes important in methadone metabolism (2B6, 3A4 and 2C19) were found in their research, based on patients’ records, to be associated with different responses to methadone treatments.
“While CYP2B6 is involved in the metabolism of S-methadone and the single nucleotide polymorphisms (SNPs) which are associated with plasma S-methadone concentration, the SNPs on CYP3A4 are associated with withdrawal symptoms and side-effects, and those on CYP2C19 with methadone dose,” Liu said.
The team believes that their findings provide a path toward using metabolic and opioid receptor genes for identifying or even predicting methadone concentrations in blood, methadone dosage and the treatment responses required.
However, Liu said the validity of their results might be impacted by the small number of patients studied, adding that the pharmacogenomic study of methadone therapy is still in its initial stages and further research methods need to be developed.
“However, if the associations between genotypes and treatment responses can be confirmed, it might be possible to have genotype information recorded on people’s National Health Insurance cards for future medication dosage adjustments, and potentially for the avoidance of withdrawal symptoms and adverse reactions, as well as increase the effectiveness of treatment,” Liu said.