Drug use was markedly reduced in both treatment conditions but there were significant differences in the prevalence of specific drugs with more opioid ( 1.5 vs. 0.2 % ; p = 0.03 ) , less amphetamine ( 0.2 vs. 2.8 % ; p < 0.001 ) and less marijuana ( 1.7 vs. 10.2 % ; p < 0.001 ) positive urine tests in the methadone vs. Suboxone groups .