The let??ter also poin??ted to in??form??a??tion from the Cen??ters for Dis??ease Con??trol and Pre??ven??tion, which noted that it is com??mon for meth??adone clin??ic pa??tients to con??tin??ue to use heroin and oth??er drugs such as co??caine and marijuana and al??co??hol after ad??mis??sion to treat??ment.