Table 2   Patterns of ecstasy and cannabis use in the two user groups (n=28 in each group) Patterns of use Ecstasy users                                   Cannabis users* Ecstasy use Cannabis use Cannabis use Regular/sporadic/no use 26/2/0 22/1/5 23/2/3 Estimated total dose 93.4 (119.9) tablets [range 20-500]     Average frequency of use (days per month) 2.4 (1.6) [range 0.75-8] 20.7 (11.5) 20.95 (10.2) Average estimated daily or one night dose 1.4 (0.9) tablets [range 0.5-3.5] 650 (635) mg daily 724 (608) mg daily Duration of regular use in regular users 27 (18) months [range 6-60] 66.6 (37) months 35.1 (24) months Age at onset of use 19.4 (3.3) y [range 14-27] 16.6 (2.9) y 17.1 (2.4) y Time since last dose 41 (71.1) days [range 7 days-1 y, median 23 days] 4.3 (5.3) days [median 2 days] 4.0 (15.5) days [median 1 day] THC-Screen in urine sample on study day   17 positive/11 negative 20 positive/8 negative * Cannabis users=persons who were matched for cannabis use with the ecstasy users. Values in () are SD.