Two formulations of morphine citrate were synthesized: trimorphine citrate, 3(MH)+(C6H5O7)3- and morphine sodium citrate, 3(MH)+3Na+2(C6H5O7)3-. Four healthy individuals volunteered to undergo electromotive administration of the two formulations. Application of electric current (2 mA) to solutions of trimorphine citrate for 1 h resulted in iontophoretic transcutaneous administration of therapeutic quantities of morphine, without deleterious reduction in the pH of the drug solutions. Application of a 2-mA current to solutions of morphine sodium citrate for 2 h resulted in combined iontophoretic and electrophoretic delivery of morphine with increased administration rates and an improved buffering capacity of the drug solutions.