using membranes from the same skin section , the permeability coefficients of three opioid alkaloids , morphine , codeine , and hydromorphone , were considerably lower , at 9.3 x 10 ( -6 ) , 4.9 x 10 ( -5 ) , and 1.4 x 10 ( -5 ) cm/hr , respectively .
C0026549
morphine
C0009214
codeine