ended questionnaire was used to record patients’ sociodemographic characteristics, serological status, history of substance use, and previous psychiatric pharmacological treatment as well as other concomitant treatments. Substance use disorders and other psychiatric disorders were diagnosed according to DSM-IV criteria, using the Spanish version of the Psychiatric Research Interview for Substance and Mental Disorders for axis I and II . The degree of addiction-related impairment was assessed using the Spanish version of the Addiction Severity Index . The use of illegal opiates was evaluated retrospectively by reviewing the results of the last 4 urine tests performed over 2 months before study inclusion. Urinalyses for the detection of heroin consumption were carried out at the centre, 1 day at random every 1 or 2 weeks, under supervision of the nursing staff. It was considered that illegal opiates had been used when 2 or more urinalyses tested positive for morphine metabolites. Determination of morphine and codeine metabolites in urine was performed by a gas chromatography– mass 
spectrometry method. This method allows the identification of 6-monoacetylmorphine in urine, which can be used as a confirmatory marker of heroine abuse. These results were used to group patients as responders and nonresponders. Because the definition of the Responder and Nonresponder phenotype is difficult to establish, it was decided to exclude subjects with subthreshold urine controls, that is, only one positive urine test in the last four screening procedures. Genetic Analysis A collection of 20 mL of blood was done to extract DNA from leukocytes to 9671117 evaluate allelic variants of genes encoding the following proteins: cytochrome P450 3A5; cytochrome P450 2D6; cytochrome P450 2B6, cytochrome P450 CYP2C9, cytochrome P450 CYP2C19, and the Multidrug Resistance 1 transporter . The genotyping of all mentioned genes but CYP2B6 was performed using a DNA microarray. Details on the allelic variants monitored per gene as well as performance of the microarray have been previously described. Briefly, target DNA for hybridization was prepared by amplification of all genes except MedChemExpress JNJ-7777120 CYP2D6 in several multiplex PCR reactions. The gene CYP2D6 was amplified together with a May 2011 | Volume 6 | Issue 5 | e19527 Pharmacogenetics and Methadone Treatment Response Pa Responders N = 76 Male Age, mean 6 SD Years at school 6 SD Single Criminal background Live with family Employed HIV+ HCV+ Lifetime psychiatric comorbidity Months of heroin use 6 SD Days of heroin 30 days 6 SD Days of cocaine 30 days 6 SD Nicotine cigarettes/ day 6 SD Concomitant medication benzodiazepines antiretrovirals anticonvulsants SSRI other antidepressant antipsychotics antibiotics 39 13 9 13 9 14 6 53 3967 963 30 40 58 22 31 59 45 144680 061 266 22611 Nonresponders N = 29 21 3669 863 13 18 19 10 9 18 14 121667 16610 7612 26613 1.000 0.076 0.060 0.629 0.248 0.764 0.205 0.380 0.139 0.416 0.192,0.001 0.123 0.172 shorter deletion-specific fragment in a long-range PCR reaction. Similarly, a separate long-range multiplex PCR reaction with the CYP2D6 gene and a short duplication-specific fragment was carried out for the identification of individuals carrying multiple copies of the CYP2D6 gene. CYP2B6 genotyping of two SNP positions was performed by TaqMan 59-nuclease chain reaction assay using commercially available kit for 516GRT and previously published probes and primers for 785ARG. The PCR reaction was performed acc
