Iontophoretic delivery of ropinirole hydrochloride: effect of current density and vehicle formulation

The objectives of this work were 1) to establish the feasibility of the transdermal iontophoretic delivery of ropinirole hydrochloride; 2) to investigate the possibility of delivering therapeutic doses of this drug; and 3) to determine the key factors that control ropinirole electrotransport.

A series of in vitro transdermal iontophoretic experiments were instituted to study the effects of drug concentration, co-ion concentration, intensity of current, and application time on ropinirole flux. The convective contribution to ropinirole electrotransport was evaluated by following the transport of the electroosmotic marker mannitol.

Ropinirole flux decreased dramatically in the presence of competing ions. This effect was observed even when the molar fraction of the two competing cations was kept constant. Anodal flux of mannitol decreased with drug concentration, indicating a possible alteration of the skin permselectivity. In the absence of competing co-ions, ropinirole transport number reached a maximum value (8-13%). In these conditions, the main factor controlling drug delivery was the intensity of current applied.

Transdermal iontophoresis allowed the delivery of therapeutic doses of ropinirole. The dose administered and the input rate were controlled by the judicious choice of the key delivery factors here described.