Study of Controllable Delivery of Smoking Cessation Drug Cytisine Using Transdermal Iontophoresis

OBJECTIVE To investigate the anodal iontophoresis of a partial agonist of nicotinic acetylcholine receptor cytisine(CTS) across porcine skin in vitro. METHODS Analytical method of CTS was developed and validated by using HPLC-PDA. The effect of current densities, drug concentrations and drug reservoir on iontophoretic delivery of CTS across skin was investigated. Acetaminophen was used as a marker to deconvolute the contribution of electromigration and electroosmosis during iontophoresis of CTS. RESULTS Passive delivery of CTS from aqueous solution was minimal; however, application of iontophoresis significantly enhanced the transdermal delivery of CTS, and increasing current density from 0.15 mA·cm^-2 to 0.5 mA·cm^-2 produced a linear increase in steady-state iontophoretic flux of CTS (J=4 52.8I+31.51, r=0.998 3). In the presence of a current of 0.5 mA·cm^-2, the increase in donor concentration (2.5, 5.0 and 10.0 mg·mL^-1) produced a statistically significant increase in cumulative permeation. Co-iontophoresis of acetaminophen confirmed that electromigration was the dominant transport mechanism for CTS(˃90%). Transport efficiencies for CTS were good(6.63%-8.82%). Furthermore, the delivery efficiencies, i.e., the fraction of the drug in the formulation that was delivered were high(>40% at 0.5 mA·cm^-2). Cumulative permeation of CTS from HEC hydrogel, a drug reservoir for iontophoretic systems, was (1 551.94±322.19)μg×cm^-2; this was statistically equivalent to that from solution. CONCLUSION The results demonstrate that therapeutic amounts of CTS can be easily delivered by transdermal iontophoresis with hydrogel patches of modest surface area.