Genetic Polymorphisms In The CYP2A6: Implications For Inter-Individual Differences In Nicotine Metabolism

Terdapat pelbagai bentuk CYP2A6. la memetabolismekan nikotina, kotinina dan sesetengah pro-karsinogen serta drug. Variasi dalam aiel CYP2A6 boleh mengurangkan risiko untuk merokok dan frekuensi bagi 'PM' adalah lebih rendah dikalangan penduduk Barat (Caucasion) berbanding penduduk Asia. Objektif kajian kami adalah untuk membangunkan kaedah genetik molekul dan analitikal bagi mengkaji kepelbagaian CYP2A6 di Malaysia. Subjek terdiri daripada dewasa yang sihat berketurunan Melayu, Cina dan India yang telah bersetuju menyertai kajian ini. DNA yang telah diesktrak daripada darah menggunakan kaedah 'saltingout' seterusnya digunakan untuk mengesan genotip CYP2A6 melalui kaedah PCR. CYP2A6 is polymorphic. It metabolizes nicotine, cotinine, several pro-carcinogens and drugs. Variant CYP2A6 alleles reduced risks for smoking and Caucasian have lower frequencies for the PM phenotype than Asians. The objective of our study was to develop analytical and molecular genetic methods for studying CYP2A6 polymorphism in Malaysia. Subjects were healthy adult Malays, Chinese and Indians who gave informed consents. DNA was extiacted from blood using salting out procedures and subjected to PCR-genotyping for CYP2A6

VALIDATION FOR QUANTITATIVE OF METHADONE ENANTIOMERS AND ITS MAJOR METABOLITE USING VANCOMYCIN COLUMN COUPLED WITH MASS SPECTROMETRIC DETECTION AND ITS APPLICATION TO CLINICAL SAMPLES

Objective: To develop method to measure both methadone enantiomers and its major metabolite 2-ethylidene-1, 5-dimethyl-3, 3-diphenylpyrrolidine (EDDP) in clinical samples Methods: Five hundredmicroliters plasma/serum was extracted using solid phase extraction (mixed mode SPE-C8/SCX). The eluent was evaporated, reconstituted in mobile phase (95:5, 0.003% formic acid in methanol: 20 mM* ammonium formate) and injected. Result: The recoveries of methadone enantiomers and EDDP were 97% and 89% respectively. Under this condition, methadone enantiomers were successfully separated at baseline but not EDPP. Precision of spiked plasma for intra-day and inter-day was less than five for both methadone enantiomers and less than 12 for EDDP at medium and high quality control samples. Linear relationship between peak area ratio and internal standard were obtained for methadone in the range 5-1000ng/ml, and for EDDP from 5-500ng/ml with correlation coefficients greater than 0.99. The limit of quantification was 5ng/ml. Conclusion: The assay was used to analyse serum samples obtained from patients enrolled in a methadone maintenance treatment program

Better retention of Malaysian opiate dependents treated with high dose methadone in methadone maintenance therapy

<p>Abstract</p> <p>Background</p> <p>Methadone is a synthetic opiate mu receptor agonist that is widely used to substitute for illicit opiates in the management of opiate dependence. It helps prevent opiate users from injecting and sharing needles which are vehicles for the spread of HIV and other blood borne viruses. This study has the objective of determining the utility of daily methadone dose to predict retention rates and re-injecting behaviour among opiate dependents.</p> <p>Methods</p> <p>Subjects comprised opiate dependent individuals who met study criteria. They took methadone based on the Malaysian guidelines and were monitored according to the study protocols. At six months, data was collected for analyses. The sensitivity and specificity daily methadone doses to predict retention rates and re-injecting behaviour were evaluated.</p> <p>Results</p> <p>Sixty-four patients volunteered to participate but only 35 (54.69%) remained active and 29 (45.31%) were inactive at 6 months of treatment. Higher doses were significantly correlated with retention rate (p < 0.0001) and re-injecting behaviour (p < 0.001). Of those retained, 80.0% were on 80 mg or more methadone per day doses with 20.0% on receiving 40 mg -79 mg.</p> <p>Conclusions</p> <p>We concluded that a daily dose of at least 40 mg was required to retain patients in treatment and to prevent re-injecting behaviour. A dose of at least 80 mg per day was associated with best results.</p

118A>G AND IVS2+691G>C POLYMORPHISMS OF OPRM1 GENE HAVE NO INFLUENCE ON COLD-PAIN SENSITIVITY AMONG HEALTHY OPIOID-NAIVE MALAY MALES

Objective: Common polymorphisms of the mu-type opioid receptor (OPRM1) including 118A&gt;G and IVS2+691G&gt;C may affect experimental pain responses in healthy subjects, and the effect could be ethnic-dependent. The aim of this study was to investigate the influence of these OPRM1 polymorphisms on cold-pressor pain responses among healthy opioid-naive Malay males. Methods: Pain-threshold, pain-tolerance, and pain-intensity in response to the cold pressor test (CPT) were measured in healthy opioid-naive Malay males. DNA was extracted from the collected venous blood before PCR-genotyping. Repeated measure analysis of variance (RM-ANOVA) was used to compare CPT responses and OPRM1 polymorphisms (118A&gt;G and IVS2+691G&gt;C) according to their genotypes and allelic additive models, genotype dominant and recessive models, haplotypes, and diplotypes.Results: A total of 152 participants were recruited. Both 118A&gt;G and IVS2+691G&gt;C polymorphisms were not associated with cold-pressor pain-threshold, pain-tolerance and pain-intensity despite using genotypes and allelic additive models and genotype dominant and recessive models (all p&gt;0.05). Likewise, there were no significant associations between haplotypes and diplotypes for the 118A&gt;G and IVS2+691G&gt;C polymorphisms and the three cold-pain responses (all p&gt;0.05). Conclusion: The common OPRM1 polymorphisms (i.e., 118A&gt;G and IVS2+691G&gt;C), are not associated with cold-pressor pain responses in healthy opioid-naive Malay males. However, this may be unique for this particular ethnicity. Other polymorphisms may be more relevant for this population, and this should be further investigated.Keywords: Cold pressor test (CPT), Mu-type opioid receptor (OPRM1), Opioid receptor, mu 1 gene (OPRM1), Pain-threshold, Pain-tolerance, Pain-intensity, Opioid-naive, Male, Malay

A Nested Allele-Specific Multiplex Polymerase Chain Reaction Method for the Detection of DRD2 Polymorphisms

Background: The dopamine D2 receptor gene (DRD2) plays a role in many diseases such as schizophrenia, Parkinson’s disease, and addictive behaviour. Methods currently available for the detection of DRD2 polymorphisms are costly and cannot detect all 8 polymorphisms of our research interest simultaneously (Val96Ala, Leu141Leu, Val154Ile, Pro310Ser, Ser311Cys, TaqI A, A-241G, and −141C Ins/Del). Therefore, we developed a nested multiplex polymerase chain reaction (PCR) for simultaneous detection of these polymorphisms. Methods: Genomic DNA was extracted from blood using standardised methods. Primers specific at the 3’-end for the polymorphic sites were designed. A two-step PCR method was developed. In the first PCR, a region from exon 3 to 4, exon 7, the promoter region, and the 3’-region of DRD2 were specifically amplified. The products were subsequently used as templates in the second PCR. Sequencing was performed to validate the test results. Results: Specific bands corresponding to the amplified product of interest were obtained. The method was reproducible and specific when used to genotype patients with schizophrenia. The amplified sequences showed 100% homology to the DRD2 sequence. Conclusion: The method was found to be simple, rapid, specific, and reproducible for the simultaneous detection of the DRD2 polymorphisms

Population Pharmacokinetics of Colistin Methanesulfonate Sodium and Colistin in Critically Ill Patients: A Systematic Review

Understanding the pharmacokinetics parameter of colistin methanesulfonate sodium (CMS) and colistin is needed to optimize the dosage regimen in critically ill patients. However, there is a scarcity of pharmacokinetics parameters in this population. This review provides a comprehensive understanding of CMS and colistin pharmacokinetics parameters in this population. The relevant studies published in English that reported on the pharmacokinetics of CMS and colistin from 2000 until 2020 were systematically searched using the PubMed and Scopus electronic databases. Reference lists of articles were reviewed to identify additional studies. A total of 252 citation titles were identified, of which 101 potentially relevant abstracts were screened, and 25 full-text articles were selected for detailed analysis. Of those, 15 studies were included for the review. This review has demonstrated vast inter-study discrepancies in colistin plasma concentration and the pharmacokinetics parameter estimates. The discrepancies might be due to complex pathophysiological changes in the population studied, differences in CMS brand used, methodology, and study protocol. Application of loading dose of CMS and an additional dose of CMS after dialysis session was recommended by some studies. In view of inter-patient and intra-patient variability in colistin plasma concentration and pharmacokinetics parameters, personalized colistin dosing for this population is recommended

Demographic profiles and sleep quality among patients on methadone maintenance therapy (MMT) in Malaysia

Poor sleep quality was frequently reported by opioid dependence patients during methadone maintenance therapy (MMT). The study investigated a sample of patients on MMT to investigate the severity and prevalence of sleep problems in MMT patients. We evaluated sleep quality and disturbances of 119 Malay male patients from MMT clinics in Kelantan, Malaysia between March and July 2013 using the Pittsburgh Sleep Quality Index (PSQI)-Malay version. Patients' demographic, clinical data, past drug history and methadone treatment variables were recorded. Patients averaged 37.5 years of age (SD 6.79) and their mean age of first time illicit drug use was 19.3 years (SD 4.48). Their mean age of entering MMT was 34.7 years (SD 6.92) and the mean duration in MMT was 2.8 years (SD 2.13). The mean current daily dosage of methadone was 77.8 mg (SD 39.47) and ranged from 20 to 360 mg. The mean global PSQI score was 5.6 (SD 2.79) and 43.7% patients were identified as 'poor sleepers' (global PSQI scores >5). This study confirms the poor overall sleep quality among patients on MMT. The prevalence and severity of sleep problems in MMT patients should not be underestimated