Development and Evaluation of a Novel Mucoadhesive Film Containing <i>Acmella oleracea</i> Extract for Oral Mucosa Topical Anesthesia

<div><p>Purpose</p><p>To develop an anesthetic mucoadhesive film containing <i>Acmella oleracea</i> (jambu) extract for topical use on oral mucosa.</p><p>Methods</p><p>Ethanolic extracts from aerial parts of jambu were prepared by maceration. Pigment removal was obtained by adsorption with activated carbon. Three mucoadhesive films were developed using a film casting method: 10 or 20% of crude jambu extract (10% JB and 20% JB), and 10% of crude jambu extract treated with activated carbon (10% JBC). The mucoadhesive films were characterized regarding their uniformity, thickness, pH, and spilanthol content, and their stability was evaluated during 120 days. Gas chromatography was used to quantify the amount of spilanthol. <i>In vitro</i> tests determined the permeation of spilanthol across pig esophageal epithelium mucosa in Franz diffusion cells. Topical anesthetic efficacy was assessed <i>in vivo</i> using a tail flick test in mice.</p><p>Results</p><p>The three mucoadhesive films showed physical stability and visual appearances suitable for use on oral mucosa. The permeation study revealed that the spilanthol from 10% JBC presented higher flux and permeability coefficient values, compared to 10% or 20% JB (p < 0.001). Moreover, 10% JBC showed better topical anesthetic efficacy than the other films (p < 0.01).</p><p>Conclusion</p><p>Mucoadhesive film containing crude extract of jambu treated with activated carbon is a potential alternative for oral, topical use, encouraging future clinical studies.</p></div

Encapsulation of ropivacaine in a combined (donor-acceptor, ionic-gradient) liposomal system promotes extended anesthesia time

<div><p>Ropivacaine is a local anesthetic with similar potency but lower systemic toxicity than bupivacaine, the most commonly used spinal anesthetic. The present study concerns the development of a combined drug delivery system for ropivacaine, comprised of two types of liposomes: donor multivesicular vesicles containing 250 mM (NH₄)₂SO₄ plus the anesthetic, and acceptor large unilamellar vesicles with internal pH of 5.5. Both kinds of liposomes were composed of hydrogenated soy-phosphatidylcholine:cholesterol (2:1 mol%) and were prepared at pH 7.4. Dynamic light scattering, transmission electron microscopy and electron paramagnetic resonance techniques were used to characterize the average particle size, polydispersity, zeta potential, morphology and fluidity of the liposomes. <i>In vitro</i> dialysis experiments showed that the combined liposomal system provided significantly longer (72 h) release of ropivacaine, compared to conventional liposomes (~45 h), or plain ropivacaine (~4 h) (p <0.05). The pre-formulations tested were significantly less toxic to 3T3 cells, with toxicity increasing in the order: combined system < ropivacaine in donor or acceptor liposomes < ropivacaine in conventional liposomes < plain ropivacaine. The combined formulation, containing 2% ropivacaine, increased the anesthesia duration up to 9 h after subcutaneous infiltration in mice. In conclusion, a promising drug delivery system for ropivacaine was described, which can be loaded with large amounts of the anesthetic (2%), with reduced <i>in vitro</i> cytotoxicity and extended anesthesia time.</p></div

Analgesia (von Frey test) induced by ropivacaine in mice.

<p>The anesthetic was used in solution (0.75% and 2% plain RVC) or encapsulated in HSPC:cholesterol (2:1 mol %) liposomes: donor (RVC in LMVV 7.4_{in+ sulfate}), acceptor (RVC in LUV 5.5 _in) and combined formulation (RVC in LMVV 7.4_{in+ sulfate} + LUV 5.5_in).</p

Permeation profiles across pig esophagus mucosa of spilanthol from mucoadhesive films applied under finite dose conditions (mean ± SD, n = 6).

<p>10% JB: mucoadhesive containing 10% of dry crude extract; 20% JB: mucoadhesive containing 20% of dry crude extract; 10% JBC: mucoadhesive containing 10% of dry extract treated with activated carbon (4%).</p

Parameters for the permeation (5 h) through pig esophageal mucosa, under finite dose conditions, of spilanthol applied using the three mucoadhesive films tested (mean ± SEM; n = 6; JB: dry crude extract; JBC: dry crude extract treated with 4% of activated carbon).

<p>Parameters for the permeation (5 h) through pig esophageal mucosa, under finite dose conditions, of spilanthol applied using the three mucoadhesive films tested (mean ± SEM; n = 6; JB: dry crude extract; JBC: dry crude extract treated with 4% of activated carbon).</p

Illustration of the crude extract treatment process with activated carbon.

<p>Illustration of the crude extract treatment process with activated carbon.</p

Physicochemical parameters (Mean±SD) of the mucoadhesive films and spilanthol extracted from mucoadhesive films.

<p>Physicochemical parameters (Mean±SD) of the mucoadhesive films and spilanthol extracted from mucoadhesive films.</p

<i>In vitro</i> release kinetics of RVC, plain or encapsulated in HSPC:cholesterol liposomes: donors (LMVV 7.4_{in+ sulfate}), acceptors (LUV 5.5_in), and their combination (LMVV 7.4_{in+ sulfate} + LUV 5.5_in); Ambient temperature (25°C), N = 3.

<p><i>In vitro</i> release kinetics of RVC, plain or encapsulated in HSPC:cholesterol liposomes: donors (LMVV 7.4_{in+ sulfate}), acceptors (LUV 5.5_in), and their combination (LMVV 7.4_{in+ sulfate} + LUV 5.5_in); Ambient temperature (25°C), N = 3.</p

Duration of analgesia and AUC values for the three tested mucoadhesives and EMLA^®.

<p>Duration of analgesia and AUC values for the three tested mucoadhesives and EMLA^®.</p

Illustration of the mucoadhesive film production.

<p>Illustration of the mucoadhesive film production.</p