Table 1.
Experimental studies with local anesthetics encapsulated into various nanoparticles
| Local anesthetic drug | Nanoparticles | Subjects (administration route) | Antinociceptive test | Results | Ref |
|---|---|---|---|---|---|
| Benzocaine | PLGA, PLA, PCL | Mice (injection into the popliteal space) | PWTP | Pharmacological assessment indicated that encapsulation of benzocaine in polymeric nanocapsules prolonged its anesthetic effect compared with free benzocaine | [83] |
| Lidocaine/prilocaine | Polymeric nanocapsules | Rat (oral mucosa) | Tail-flick | The formulation provided effective and longer-lasting superficial anesthesia at the intraoral mucosa during medical and dental procedures | [84] |
| Bupivacaine | Alginate/chitosan (ALG–CHIT)-Alginate/bis (2-ethylhexyl) sulfosuccinate (ALG–AOT) | Mice (popliteal space) | PWTP | Comparison among formulations displayed that 0.125% bupivacaine-loaded ALG–CHIT and bupivacaine-loaded ALG–AOT improved the analgesia 1.5- and 2.16-fold, respectively, compared with plain bupivacaine | [85] |
| Ropivacaine | Liposome | Human (oral mucosa) | Pinprick test | Extensive soft tissue anesthesia was achieved using liposome containing ropivacaine and EMLA group, when compared with ropivacaine and benzocaine gels (P < 0.0001) | [86] |
| Tetracaine | Liposome | Human (skin) | McNemars test | The formulation produced better superficial local anesthesia than EMLA | [87] |
| Bupivacaine | Alginate/chitosan | Rabbit-rat (intraoral or intrathecal injections) | Observation of the aversive response to the rat upper lip pinching | The analgesic properties of bupivacaine increased 1.4-fold (P < 0.001) with bupivacaine 0.5%-loaded alginate–chitosan nanoparticles after infraorbital nerve blockade | [88] |
| Tetrodotoxin | Hollow silica nanoparticles | Rat (sciatic nerve injection) | Neuro-behavioral testing | The sustained release of tetrodotoxin encapsulated in hollow silica nanoparticles with diameter of 28 nm prolonged duration of action and at the same time reduced systemic toxicity | [89] |
| Tetrodotoxin | Poly(triol dicarboxylic acid)-co-poly(ethylene glycol) | Rat (sciatic nerve injection) | Neuro-behavioral testing | Tetrodotoxin released from polymers created nerve block duration, from several hours to 3 days, with insignificant local or systemic toxicity | [90] |
PWTP paw withdrawal threshold to pressure, PLGA poly(lactic-co-glycolic acid), PLA polylactic acid, PCL polycaprolactone, EMLA eutectic mixture of local anesthetics