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Anesthetic efficacy and plasmatic concentration of liposome-encapsulated ropivacaine in dental anesthesia

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Author(s):
Michelle Franz Montan
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
Defense date:
Examining board members:
Maria Cristina Volpato; Juliana Cama Ramacciato; Fabio Andre dos Santos; Eduardo Dias de Andrade; Roger William Fernandes Moreira
Advisor: Francisco Carlos Groppo; Eneida de Paula; Maria Cristina Volpato
Abstract

A new pharmaceutical formulation of local anesthetic, liposome encapsulated, has been studied in medicine and recently in dentistry. The aims of the present study were to evaluate anesthetic efficacy in topical and infiltration anesthesia, and pharmacokinetic parameters of liposome-encapsulated ropivacaine in 4 random, crossed and double-blind studies, with a one week interval between sections. Chapter 1: liposome-encapsulated 2% ropivacaine (RL2), 20% Benzocaine (B20), liposomal placebo (PL) and placebo (P) were compared in relation to the efficacy of topical anesthesia and influence on pulpal response after topical application in the buccal fold of the upper lateral incisors, in 40 volunteers. RL2 was as efficacious as B20 in reducing pain during needle insertion and concerning soft tissue anesthesia (p>0.05) and both agents were better than PL e P formulations (p<0.05). None of the formulations influenced pulpal response. Chapter 2: liposome-encapsulated 2% ropivacaine (RL2), liposome-encapsulated 1% ropivacaine (RL1), 2.5% lidocaine and 2.5% prilocaine cream (EMLA) and liposomal placebo (PL) were evaluated concerning their efficacy in reducing pain during needle insertion and anesthetic injection after topical application at the palatal mucosa of the upper left canine. EMLA was the most effective in reducing pain during needle insertion (p<0.05), however none of the tested formulations was effective in reducing pain during anesthetic injection (p>0.05). None of the formulations was effective as a topical anesthetic in the palatine mucosa. Chapter 3: forty volunteers received 1.8mL of liposomeencapsulated 0.5% ropivacaine (RLipo), 0.5 % ropivacaine with 1:200,000 epinephrine (Repi), 0.5% ropivacaine (R) and 2% lidocaine with 1:100,000 epinephrine (Lepi), as an infiltration injection in the buccal fold of the right maxillary canine region. The onset and duration of pulpal anesthesia were evaluated through electric stimuli application and in soft tissue by pressure stimuli. No difference in onset of anesthesia was observed among anesthetic formulations (p>0.05). Repi and Lepi showed longer pulpal anesthesia when compared to RLipo and R (p<0.05). Repi provided longer gingival anesthesia than the other formulations (p<0.05). Liposome-encapsulated ropivacaine was not effective in maxillary infiltration anesthesia. Chapter 4: plasma levels of ropivacaine were analyzed by high performance liquid chromatography (HPLC) after infiltration of 1.8mL of 0.5% ropivacaine with 1:200,000 epinephrine and liposome-encapsulated 0.5% ropivacaine in the buccal fold of the maxillary right canine region in 14 volunteers. There were no statistically differences (p>0.05) among pharmacokinetics parameters between the two anesthetic formulations. Final conclusion: There is no advantage in the use of liposome-encapsulated 0.5% ropivacaine in infiltration anesthesia or liposome-encapsulated 1 and 2% ropivacaine in topical anesthesia in palatal mucosa. In the buccal mucosa, as it showed similar efficacy of 20% benzocaine, liposome-encapsulated 2% ropivacaine can be an option to this anesthetic. Liposome-encapsulated ropivacaine and ropivacaine with epinephrine showed similar pharmacokinetic. (AU)