local anesthetics buccal delivery enhanced by iontophoresis

local anesthetics buccal delivery enhanced by iontophoresis

LOCAL ANESTHETICS BUCCAL DELIVERY
ENHANCED BY IONTOPHORESIS
CUBAYACHI C(1), COUTO R O(1), MONTEIRO E SILVA S A(2), DE GAETANI C M(1), FREITAS O(1),
LOPEZ R F V(1)
(1) School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Sao
Paulo, Brazil. (2) Medicine Department, Federal University of São Paulo, Sao Paulo, Brazil.
[email protected]
Keywords: Iontophoresis, Prilocaine hydrochloride, Lidocaine hydrochloride, Permeation
enhancement, Buccal Drug Delivery.
Introduction: Local anesthesia of buccal cavity is a fundamental step on the majority of dentistry
procedures. The effective non-invasive administration of local anesthetics in buccal cavity in
replacement of the painful injections would improve the routine and surgical procedures by reducing
costs, providing patient compliance, facilitating the administration and offering lower risks of
contamination and toxicity. The rate of release and permeation of the anesthetic could be modulated
by using pharmaceutical adjuvants and iontophoresis. Objective: In vitro evaluation of the influence
of iontophoresis on the permeation of lidocaine (LCL) and prilocaine (PCL) hydrochlorides through
porcine esophageal mucosa from a mucoadhesive semisolid formulation. Methods: Hidroxypropyl
methylcellulose hydrogel containing both LCL 2.5% and PCL 2.5% was obtained and the influence of
anodic iontophoresis (1 mA/cm2 for 1 hour) on the permeation and retention of local anesthetics was
evaluated by using modified Franz diffusion cells and porcine esophageal mucosa. Anesthetic
contents were determined using a HPLC-PDA method developed and validated in our laboratory.
Results: Iontophoresis enhanced 12 times the permeated amount, flux and permeation coefficient of
PCL compared to passive (no-current application) experiments (p<0.01). The amount of PCL
recovered from the mucosa after 1 hour of iontophoresis treatment was 10-folds greater than after
passive permeation (p<0,001). Anesthetic presence into the mucosa is desirable for a local action
combined with deep action achieved by the amount of drug permeated. Moreover, it may work as a
drug reservoir, providing a longer duration of action. For LCL, neither of these parameters was
affected by iontophoresis. Conclusion: Iontophoresis greatly enhanced the permeation and
retention in buccal mucosa of the PCL and could be a promising strategy in the development of a
noninvasive anesthesia method for dentistry procedures. Financial Support: FAPESP, CAPES,
CNPq.