Abstract
To determine whether the permeation capacity and analgesic efficacy of articaine (ATC) could be increased and cytotoxicity decreased by encapsulation in poly(ɛ-caprolactone) nanocapsules (ATCnano), aiming at local or topical anesthesia in dentistry. Cellular viability was evaluated (using the MTT test and fluorescence microscopy) after 1 h and 24 h exposure of HaCaT cells to ATC, ATCnano, ATC with epinephrine (ATCepi), and ATC in nanocapsules with epinephrine (ATCnanoepi). The profiles of permeation of 2% ATC and 2% ATCnano across swine esophageal epithelium were determined using Franz-type vertical diffusion cells. Analgesic efficacy was evaluated with a von Frey anesthesiometer in a postoperative pain model in rats, comparing the 2% ATC, 2% ATCnano, 2% ATCepi, and 2% ATCnanoepi formulations to 4% ATCepi (a commercially available formulation). We show that use of the nanocapsules decreased the toxicity of articaine (P<0.0001) and increased its flux (P = 0.0007). The 2% ATCepi and 4% ATCepi formulations provided higher analgesia success and duration (P<0.05), compared to 2% ATC, 2% ATCnano, and 2% ATCnanoepi. Articaine-loaded poly(ɛ-caprolactone) nanocapsules constitute a promising formulation for intraoral topical anesthesia (prior to local anesthetic injection), although it is not effective when injected in inflamed tissues for pain control, such as irreversible pulpitis.
Highlights
Articaine is an amide local anesthetic containing a thiophene ring and an ester radical in its chemical structure [1]
The encapsulation of articaine in poly(ε-caprolactone) nanocapsules is a promising strategy for dental practice since it provides decreased cytotoxicity, which can reduce the risk of nerve cell damage and paresthesia [2,8], together with increased permeability resulting in higher superficial analgesia after topical application at oral mucosa [19,20]
The polydispersion index remained at low values, showing good homogeneity of the system, which confirmed the results previously reported by our group [15,16,17,18]
Summary
Articaine is an amide local anesthetic containing a thiophene ring and an ester radical in its chemical structure [1]. Articaine has been shown to provide a better quality of pulpal anesthesia in inflammatory hypernociception, such as irreversible pulpites [3,4]. It is effective in lower molar pulpal anesthesia after its buccal infiltration, which is usually achieved using blockade techniques [4,5,6,7]. There have reports of paresthesia and transitory post-operative sensitivity associated with the use of articaine, which could be related to the concentration in which the compound is used (4%) [8]
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