Effects of epinephrine, lidocaine, and prilocaine on viability and differentiation capacity of human adipose stem cells.

INTRODUCTION: Local anesthetics (LAs) are routinely administered in plastic and reconstructive surgery, e.g., as tumescent anesthesia adjunct in liposuction. Historically, these substances were assumed to act cytotoxically. Thus, the application of LA was avoided when handling adipose stem cells (ASCs). We recently determined that most LAs are not cytotoxic when ASCs are exposed to concentrations used for tumescent liposuction. However, there is limited information when combining LA with epinephrine and about the effects of prilocaine on ASCs. METHODS: We analyzed the effects of prilocaine or lidocaine in co-exposure with epinephrine on the viability of primary human ASCs, i.e., proliferation, metabolic activity, and cytotoxicity, using crystal violet-staining, PrestoBlue®-, and WST-1 assay. We quantified the impact of short-term incubation of lidocaine and epinephrine on the differentiation of ASCs into the adipogenic, chondrogenic, and osteogenic lineage. RESULTS: After 2 h, prilocaine (10 mM) significantly reduced metabolic activity and cell numbers, whereas lidocaine only inhibited metabolic activity. After 6 h, prilocaine (10 mM) and lidocaine significantly decreased metabolic activity as well as cell numbers. The application of high concentrations of epinephrine did not affect cell numbers but diminished metabolic activity. Combining lidocaine with epinephrine had no additional cytotoxic effect. Differentiation into the chondrogenic lineage was significantly inhibited by epinephrine. CONCLUSIONS: Deducing from our data, neither lidocaine combined with epinephrine nor prilocaine has a cytotoxic impact on ASCs in vitro at concentrations equivalent to those in tumescent anesthesia and has no long-lasting effect on the differentiation capacity of ASCs into the osteogenic and adipogenic lineage.

Inflammatory signal transduction pathways induced by prilocaine toxicity in cultured ARPE-19 cells.

Prilocaine (PRL) is a common local anesthetic. Despite the successful use of regional anesthesia for intraocular surgery, there are associated side effects that may affect the retina in case of accidental intravitreal injection. This study examined the signal transduction pathways activated by PRL toxicity and determined the protective role of nitric oxide synthase-2 (NOS2) inhibition in cultured human-derived retinal pigment epithelial cells (ARPE-19). Toxicity analysis was performed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay to detect the toxic dose of PRL and protective effectiveness of asperglaucide (ASP), an NOS2 inhibitor. Nuclear factor kappa B p65 (NF-κB p65), phosphorylated NF-κB p65, phospho-protein kinase B (AKT), NOS2, nitrotyrosine, and cleaved caspase-3 protein levels were evaluated by immunofluorescence staining and/or western blot analysis. Interleukin-6 (IL-6) and nitrated protein levels were quantified using an immunoassay, whereas caspase-3 activity and nitrite/nitrate levels were measured using a fluorometric method. A significant increase in NF-κB p65, and phosphorylated NF-κB p65 and AKT levels due to PRL toxicity was observed. Similarly, IL-6, NOS2, nitrite/nitrate, and nitrotyrosine levels were significantly higher in PRL-treated cells than in control cells. Application of ASP to PRL-treated cells reduced NF-κB p65, and phosphorylated NF-κB p65 and AKT to basal levels. IL-6, NOS2, nitrite/nitrate, and nitrotyrosine levels also considerably decreased following ASP treatment in cells experiencing PRL-induced toxicity. Moreover, the caspase-3-dependent apoptotic pathway was not activated. Our results indicate that ASP could ameliorate PRL-induced activation of NF-κB p65 that led to inflammation in cultured ARPE-19 cells.

Determination of the ED95 of intrathecal hyperbaric prilocaine with sufentanil for scheduled cesarean delivery: a dose-finding study based on the continual reassessment method.

BACKGROUND: Scheduled cesarean section is routinely performed under spinal anesthesia using hyperbaric bupivacaine. The current study was undertaken to determine the clinically relevant 95% effective dose of intrathecal 2% hyperbaric prilocaine co-administered with sufentanil for scheduled cesarean section, using continual reassessment method. METHODS: We conducted a dose-response, prospective, double-blinded study to determine the ED95 values of intrathecal hyperbaric prilocaine used with 2,5 mcg of sufentanil and 100 mcg of morphine for cesarean delivery. Each parturient enrolled in the study received an intrathecal dose of hyperbaric prilocaine determined by the CRM and the success or failure of the block was assessed as being the primary endpoint. RESULTS: The doses given for each cohort varied from 35 to 50 mg of HP, according to the CRM, with a final ED95 lying between 45 and 50 mg of Prilocaine after completion of the 10 cohorts. Few side effects were reported and patients were globally satisfied. CONCLUSIONS: The ED95 of intrathecal hyperbaric prilocaine with sufentanil 2.5 µg and morphine 100 µg for elective cesarean delivery was found to be between 45 and 50 mg. It may be an interesting alternative to other long-lasting local anesthetics in this context. TRIAL REGISTRATION: The study was registered on January 30, 2017 - retrospectively registered - and results posted at the public database clinicaltrials.gov ( NCT03036384 ).

Synergy between surfactants and mucoadhesive polymers enhances the transbuccal permeation of local anesthetics from freeze-dried tablets.

We report on the advance of freeze-dried mucoadhesive orodispersible tablets (ODTs) loaded with prilocaine (PRC) and lidocaine (LDC) hydrochlorides, aiming to promote noninvasive buccal anesthesia. The influences of combining biocompatible polymers (pullulan and HPMC K100 LV) and a blend of surfactants (oleic acid, polysorbate 80 and propylene glycol) acting as chemical enhancers on the permeation of such drugs through the esophageal porcine epithelium and in vitro mucoadhesion were investigated. The ODTs were also characterized in terms of average weight, thickness, pH, drug content, in vitro release, thermal behavior and scanning electronic microscopy. A dissolution test showed fast drug release within one hour. The drug release data for all ODTs fitted first order. No significant influence of the type of mucoadhesive polymer on release was observed, while the drug release from ODTs decreased in the presence of chemical enhancers. For the ODT containing pullulan the drug release mechanism was anomalous transport, whist for all others it was case-II transport. A remarkable synergic effect between pullulan and chemical enhancers on the permeation flux, lag time, and permeability coefficient of both drugs, but mainly for PRC was observed. Pullulan together with permeation enhancers also substantially improved the work of mucoadhesion as compared to HPMC. In contrast, HPMC improved drug retention in the epithelium. The novel drug delivery platform achieved by combining a freeze-drying technique, mucoadhesive biocompatible polymers, and chemical permeation enhancers displayed an effective strategy for the transbuccal delivery of PRC and LDC that can be used to improve needle-free buccal anesthesia.

Increase in pulse pressure on administration of a dental local anesthetic solution, prilocaine hydrochloride with felypressin in male diabetic patients with coronary heart disease.

OBJECTIVES: This study aimed to evaluate pulse pressure fluctuation on dental local anesthetic administration in diabetic patients with and without coronary heart disease undergoing tooth extraction. MATERIALS AND METHODS: This retrospective study in diabetic patients undergoing tooth extraction included 33 patients with coronary heart disease (mean age 79.3 ± 7.4, 64% male) and 49 patients without coronary heart disease (mean age 78.6 ± 6.5, 29% male). The increase in pulse pressure before and after administration of local anesthetics was compared between diabetic patients with and without coronary heart disease. RESULTS: Pulse pressure was increased in male diabetic patients with coronary heart disease compared with those without coronary heart disease following administration of 3% prilocaine hydrochloride with felypressin 0.03 IU/mL (prilocaine) (15.6 ± 15.4 mmHg in those with coronary heart disease (n = 11) versus 4.3 ± 10.9 mmHg in those without coronary heart disease (n = 13), p = 0.03). CONCLUSIONS: Prilocaine administration increased pulse pressure in male diabetic patients with coronary heart disease compared with those without coronary heart disease. Further study is needed to reveal the mechanisms involved in the increase in pulse pressure. CLINICAL RELEVANCE: This is the first study of pulse pressure fluctuation in diabetic patients with and without coronary heart disease following administration of local anesthetics. Our findings can help guide the choice of local anesthetics and serve as a predictor of coronary vascular condition in diabetic patients during dental treatment.

Bacterial inhibition efficiency of prilocaine and bupivacaine.

This study aimed to demonstrate the antibacterial effects of bupivacaine and prilocaine on Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. In our study, the in vitro antimicrobial effects of 20 mg/mL prilocaine and 5 mg/mL bupivacaine were tested against a S. aureus American-type culture collection (ATCC) 29213, P. aeruginosa ATCC 27853, and E. coli ATCC 25922, divided into Group P (Prilocaine) and Group B (Bupivacaine), respectively. S. aureus ATCC 29213, P. aeruginosa ATCC 27853, and E. coli ATCC 25922 were cultured on Mueller Hinton agar (Oxoid, Basingstoke, UK) plates for 18 to 24 hours at 37°C. In terms of inhibition zone diameters, inhibition of S. aureus ATCC 29213 was observed in both groups at the 12th and 24th hours. The 12th- and 24th-hour S. aureus ATCC 29213 value was significantly higher in Group P compared with Group B (P = .008). At the 12th and 24th hours, inhibition of E. coli ATCC 25922 was observed in both groups. The 12th- and 24th-hour E. coli ATCC 25922 value was significantly higher in Group P compared with Group B (P = .008). In our study, it was seen that prilocaine and bupivacaine had an antimicrobial effect on S. aureus and E. coli. In the comparison between these two local anesthetics (LAs), this effect was found to be significantly higher in prilocaine than bupivacaine. Therefore, we are of the opinion that antimicrobial effect potentials should also be taken into account in the selection of an LA agent in order to prevent the complications of an infection that might develop during LA infiltration and might lead to serious morbidity.

Effects of transdermal lidocaine or lidocaine with prilocaine or tetracaine on mechanical superficial sensation and nociceptive thermal thresholds in horses.

OBJECTIVE: To evaluate the transdermal local anaesthetic effect of lidocaine or lidocaine combined with prilocaine or tetracaine in horses. STUDY DESIGN: Experimental, randomized study. ANIMALS: A total of five healthy adult warmblood horses. METHODS: Horses were clipped bilaterally at the withers, cranial saddle area and caudal saddle area. Baseline measurements for mechanical superficial sensation via von Frey filaments and nociceptive thermal thresholds were performed. A 5% lidocaine patch (12 hour exposure, treatment L), a lidocaine/prilocaine cream (each 2.5%, treatment LP) and a lidocaine/tetracaine cream (each 7%, treatment LT) were applied (both 2 hour exposure). The same product was applied at the same location bilaterally, but on the right side an epidermal micro-perforation (dermaroller, 1200 needles) was performed prior to application. A total of five more measurements were performed at each location, immediately at the end of exposure time followed by hourly measurements. Thermal thresholds normalized to thermal excursion were analysed. One- or two-way anova and the Wilcoxon signed-rank test were used for statistical analysis with p<0.05 considered significant. RESULTS: Epidermal micro-perforation had no enhancing effect. Treatments L, LP, and LT resulted in increased thermal excursion (%) immediately (84.7±12.9; 100.0±0.0; 100.0±0.0) and 1 hour (81.7±66; 86.0±17.7; 87.7±14.4) after the removal of the respective product compared to baseline (66.1±9.3; 69.9±8.3; 76.5±7.8). Superficial mechanical sensation was decreased by the lidocaine-and-tetracaine cream at all time points, and by the lidocaine patch and lidocaine-and-prilocaine cream for three measurements. CONCLUSIONS AND CLINICAL RELEVANCE: Eutectic mixtures of lidocaine with either prilocaine or tetracaine led to a reduction in thermal nociception and mechanical sensation for up to 2 hours.

EMLA cream does not influence efficacy and pain reduction during pulsed-dye laser treatment of port-wine stain: a prospective side-by-side comparison.

EMLA cream was developed to reduce pain during pulsed-dye laser (PDL) treatment; however, no standard assessment for the therapeutic outcomes of PDL with EMLA creams thus far available. This comparative, prospective clinical trial evaluates laser efficacy and pain reduction during PDL treatment with EMLA cream for local topical anesthesia. Nineteen patients with untreated port-wine stain (PWS) were treated using PDL and examined in this study. Treatment specifications included Vbeam® PDL (Candela Corp.), 595-nm wavelength, 9 J/cm2 radiant exposure, 0.45 ms pulse duration, 10 mm spot size, and cryogen spray cooling (40 ms cooling plus a 20 ms delay). A topical anesthetic (EMLA cream: 2.5% lidocaine and 2.5% prilocaine) and a placebo were applied to two respective testing areas on all patients prior to treatment. The visual analog scale (VAS) was used for pain assessment. Clinical therapeutic outcomes were evaluated by visual evaluation and with the use of a chromameter 2 months after 3PDL treatments. The average VAS scores were 3.15 ± 0.95 and 8 ± 0.57 for the EMLA cream site and the placebo site, respectively, at a significance level p < 0.001. The EMLA cream site and the placebo site had clearance or fading rates of 45.08 and 44.12%, respectively (p < 0.05). No serious side effects were reported. Patients reported a consistent decrease in pain during PDL treatment when the topical anesthetic EMLA cream was administered. Treatment of PWS by PDL with EMLA cream does not lead to a decrease in efficacy or an increase in side effects; instead, it significantly reduces pain during treatment. EMLA cream is a safe and effective local topical anesthetic for PWS treatment by PDL.

Design and evaluation of lidocaine- and prilocaine-coloaded nanoparticulate drug delivery systems for topical anesthetic analgesic therapy: a comparison between solid lipid nanoparticles and nanostructured lipid carriers.

PURPOSE: Topical anesthesia analgesic therapy has diverse applicability in solving the barrier properties of skin and unfavorable physicochemical properties of drugs. Lidocaine (LID) combined with prilocaine (PRI) has been used as a topical preparation for dermal anesthesia for treatment of conditions such as paresthesia. MATERIALS AND METHODS: In this study, for combination anesthesia and overcoming the drawbacks of LID and PRI, respectively, LID- and PRI-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were prepared and characterized by determination of their particle size, drug loading capacity, stability, in vitro drug release behavior and in vitro cellular viability. Ex vivo skin permeation and in vivo anesthesia analgesic efficiency of these two systems were also evaluated and compared. RESULTS: Results revealed that combination delivery of the dual drugs exhibited more remarkable efficiency than signal drug-loaded systems. SLN systems have better ex vivo skin permeation ability than NLCs. NLC systems revealed a stronger in vivo anesthesia analgesic effect than SLN systems. CONCLUSION: It can be concluded that SLNs and NLCs have different advantages, and that both carriers are promising dual drug delivery systems for topical anesthetic analgesic therapy.

Ipsilateral and contralateral sensory changes in healthy subjects after experimentally induced concomitant sensitization and hypoesthesia.

BACKGROUND: In unilateral neuropathic pain. e.g. after peripheral nerve injury, both positive and negative sensory signs occur often, accompanied by minor but equally directed contralateral sensory changes. To mimic this feature, we experimentally aimed to induce concomitant c-fibre sensitization and block in healthy subjects and analyzed the bilateral sensory changes by quantitative sensory testing (QST) using the protocol of the German Research Network on Neuropathic Pain. METHODS: Twenty eight healthy subjects were firstly randomized in 2 groups to receive either topical capsaicin (0.6%, 12 cm2, application duration: 15 min.) or a lidocaine/prilocaine patch (25/25 mg, 10 cm2, application duration: 60 min.) on the right volar forearm. Secondly, 7-14 days later in the same area either at first capsaicin (for 15 min.) and immediately afterwards local anesthetics (for 60 min.) was applied (Cap/LA), or in inversed order with the same application duration (LA/Cap). Before, after each application and 7-14 days later a QST was performed bilaterally. STATISTICS: Wilcoxon-test, ANOVA, p < 0.05. RESULTS: Single application of 0,6% capsaicin induced thermal hypoesthesia, cold hypoalgesia, heat hyperalgesia and tactile allodynia. Lidocaine/prilocaine alone induced thermal and tactile hypoesthesia as well as mechanical and cold hypoalgesia, and a heat hyperalgesia (to a smaller extent). Ipsilaterally both co-applications induced a combination of the above mentioned changes. Significant contralateral sensory changes occurred only after the co-application with concomitant sensitization and hypoesthesia and comprised increased cold (Cap/LA, LA/Cap) and mechanical detection as well as cold pain threshold (LA/Cap). CONCLUSION: The present experimental model using combined application of capsaicin and LA imitates partly the complex sensory changes observed in patients with unilateral neuropathic pain and might be used as an additional surrogate model. Only the concomitant use both agents in the same area induces both positive and negative sensory signs ipsilaterally as well as parallel contralateral sensory changes (to a lesser extent). TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01540877 , registered on 23 February 2012.

Presynaptic facilitation by tetracaine of glutamatergic spontaneous excitatory transmission in the rat spinal substantia gelatinosa - Involvement of TRPA1 channels.

The amide-type local anesthetic (LA) lidocaine activates transient receptor potential (TRP) ankyrin-1 (TRPA1) channels to facilitate spontaneous l-glutamate release onto spinal substantia gelatinosa (SG) neurons, which play a crucial role in regulating nociceptive transmission. In contrast, the ester-type LA procaine reduces the spontaneous release of l-glutamate in SG neurons. In order to determine whether TRPA1 activation by LAs is specific to amide-types, we examined the actions of tetracaine, another ester-type LA, and other amide-type LAs on glutamatergic spontaneous excitatory transmission in SG neurons by focusing on TRP activation. Whole-cell patch-clamp recordings were performed on SG neurons of adult rat spinal cord slices at a holding potential of -70mV. Bath-applied tetracaine increased spontaneous excitatory postsynaptic current (sEPSC) frequency in a concentration-dependent manner. Tetracaine activity was resistant to the voltage-gated Na+-channel blocker tetrodotoxin, the TRP vanilloid-1 antagonist capsazepine, and the TRP melastatin-8 antagonist BCTC, but was inhibited by the non-selective TRP antagonist ruthenium red and the TRPA1 antagonist HC-030031. With respect to amide-type LAs, prilocaine had a tendency to increase sEPSC frequency, while ropivacaine and levobupivacaine reduced the frequency. In conclusion, tetracaine facilitated spontaneous l-glutamate release from nerve terminals by activating TRPA1 channels in the SG, resulting in an increase in the excitability of SG neurons. TRPA1 activation was not specific to amide-type or ester-type LAs. The facilitatory action of LAs may be involved in pain occurring after recovery from spinal anesthesia.

An investigation into the inhibitory function of serotonin in diffuse noxious inhibitory controls in the neuropathic rat.

BACKGROUND: Following neuropathy α2-adrenoceptor-mediated diffuse noxious inhibitory controls (DNIC), whereby a noxious conditioning stimulus inhibits the activity of spinal wide dynamic range (WDR) neurons, are abolished, and spinal 5-HT7 receptor densities are increased. Here, we manipulate spinal 5-HT content in spinal nerve ligated (SNL) animals and investigate which 5-HT receptor mediated actions predominate. METHODS: Using in vivo electrophysiology we recorded WDR neuronal responses to von frey filaments applied to the hind paw before, and concurrent to, a noxious ear pinch (the conditioning stimulus) in isoflurane-anaesthetised rats. The expression of DNIC was quantified as a reduction in WDR neuronal firing in the presence of conditioning stimulus and was investigated in SNL rats following spinal application of (1) selective serotonin reuptake inhibitors (SSRIs) citalopram or fluoxetine, or dual application of (2) SSRI plus 5-HT7 receptor antagonist SB269970, or (3) SSRI plus α2 adrenoceptor antagonist atipamezole. RESULTS: DNIC were revealed in SNL animals following spinal application of SSRI, but this effect was abolished upon joint application of SSRI plus SB269970 or atipamezole. CONCLUSIONS: We propose that in SNL animals the inhibitory actions (quantified as the presence of DNIC) of excess spinal 5-HT (presumed present following application of SSRI) were mediated via 5-HT7 receptors. The anti-nociception depends upon an underlying tonic noradrenergic inhibitory tone via the α2-adrenoceptor. SIGNIFICANCE: Following neuropathy enhanced spinal serotonin availability switches the predominant spinal 5-HT receptor-mediated actions but also alters noradrenergic signalling. We highlight the therapeutic complexity of SSRIs and monoamine modulators for the treatment of neuropathic pain.

In vitro oral epithelium cytotoxicity and in vivo inflammatory inducing effects of anesthetic rice gel.

In vitro cytotoxicity of lidocaine hydrochloride (LH) and prilocaine hydrochloride (PH) to oral epithelial cells, isolated from tissue specimens of healthy volunteers, were evaluated. Cell vitality after treating with 1-20% anesthetic solutions for 5 and 30 min was investigated using F-actin and 4',6-diamidino-2-phenylindole staining technique and observed by fluorescence microscopy. Vitality rate of more than 90% was found in all anesthetic groups at both durations whereas no survived cell was found in a positive control group (sodium dodecyl sulfate). Lactate dehydrogenase (LDH) assay was performed to confirm the safety of both anesthetic solutions. Cell culture medium after treating with LH or PH for 5 and 30 min were collected and analyzed using commercial kits. The results showed no significant difference between the test groups and negative control group (untreated culture) with low LDH levels. In vivo inflammatory inducing effect of 5, 10, 20% LH or PH loaded rice gels was investigated in healthy volunteers. Tumor necrosis factor alpha (TNF-α) in gingival cervicular fluid was determined by ELISA technique. It was found that the expression of TNF-α was not different from the baseline. The expression of this inflammatory mediator caused by the commercial gel was higher than those of both anesthetic rice gels. It might be due to the effects of other excipients in the formulation of the commercial product. It is concluded that LH or PH possess no cytotoxicity to oral epithelium and the developed rice gel base and LH and PH rice gels do not induce inflammatory effect to oral tissues.

Low back skin sensitivity has minimal impact on active lumbar spine proprioception and stability in healthy adults.

The purpose of the current work was to (1) determine whether low back cutaneous sensitivity could be reduced through the use of a topical lidocaine-prilocaine anesthetic (EMLA(®)) to mirror reductions reported in chronic lower back pain (CLBP) patients, as well as to (2) identify whether reductions in cutaneous sensitivity resulted in decreased lumbar spine proprioception, neuromuscular control and dynamic stability. Twenty-eight healthy participants were divided equally into matched EMLA and PLACEBO treatment groups. Groups completed cutaneous minimum monofilament and two-point discrimination (TPD) threshold tests, as well as tests of sagittal and axial lumbar spine active repositioning error, seated balance and repeated lifting dynamic stability. These tests were administered both before and after the application of an EMLA or PLACEBO treatment. Results show that low back minimum monofilament and TPD thresholds were significantly increased within the EMLA group. Skin sensitivity remained unchanged in the PLACEBO group. In the EMLA group, decreases in low back cutaneous sensitivity had minimal effect on low back proprioception (active sagittal and axial repositioning) and dynamic stability (seated balance and repeated lifting). These findings demonstrate that treating the skin of the low back with an EMLA anesthetic can effectively decrease the cutaneous sensitivity of low back region. Further, these decreases in peripheral cutaneous sensitivity are similar in magnitude to those reported in CLBP patients. Within this healthy population, decreased cutaneous sensitivity of the low back region has minimal influence on active lumbar spine proprioception, neuromuscular control and dynamic stability.

Biocompatible lidocaine and prilocaine loaded-nanoemulsion system for enhanced percutaneous absorption: QbD-based optimisation, dermatokinetics and in vivo evaluation.

Barrier properties of the skin and physicochemical properties of the drugs are the main hiccups in delivering local anaesthetic molecules topically. The present work endeavours for systematic optimisation and evaluation of nanoemulsions (NEs) of local anaesthetic drugs, lidocaine and prilocaine, employing the systematic approach of Quality by Design. A 3(3) Box-Behnken design was employed for systematic optimisation of the factors obtained from screening studies employing Plackett-Burman design and risk assessment studies. The superior permeation rates, and higher concentrations of the drugs in skin layers from the optimised NE carriers, were achieved in permeation and dermatokinetic studies, when compared to marketed cream. Furthermore, rapid onset of action was demonstrated by the NE system in rabbit eye corneal reflex model and biocompatibility was confirmed from the absence of any marked skin change(s) in the normal skin histology. The developed NE systems demonstrated it as a promising carrier for topical delivery of lidocaine and prilocaine.

Sodium Channel Inhibitors Reduce DMPK mRNA and Protein.

Myotonic dystrophy type 1 (DM1) is caused by an expanded trinucleotide (CTG)n tract in the 3' untranslated region (UTR) of the dystrophia myotonica protein kinase (DMPK) gene. This results in the aggregation of an expanded mRNA forming toxic intranuclear foci which sequester splicing factors. We believe down-regulation of DMPK mRNA represents a potential, and as yet unexplored, DM1 therapeutic avenue. Consequently, a computational screen for agents which down-regulate DMPK mRNA was undertaken, unexpectedly identifying the sodium channel blockers mexiletine, prilocaine, procainamide, and sparteine as effective suppressors of DMPK mRNA. Analysis of DMPK mRNA in C2C12 myoblasts following treatment with these agents revealed a reduction in the mRNA levels. In vivo analysis of CD1 mice also showed DMPK mRNA and protein down-regulation. The role of DMPK mRNA suppression in the documented efficacy of this class of compounds in DM1 is worthy of further investigation.

Prilocaine hydrochloride protects zebrafish from lethal effects of ionizing radiation: role of hematopoietic cell expansion.

Drug repositioning is an approach of significant translatability, and the present study was undertaken to screen a collection of FDA approved small-molecule clinical compounds for identification of novel radioprotective agents. Screening of JHCCL (Johns Hopkins Clinical Compound Library), a collection of 1,400 FDA approved small molecules, lead to identification of prilocaine hydrochloride, a local anesthetic used widely during dental procedures, as a potential radioprotector. Prilocaine, at a concentration of 20 µM, protected zebrafish from radiation induced (20 Gy) pericardial edema (PE), microphthalmia and rendered 60 % survival advantage over radiation exposed controls. While 40 % survival advantage over radiation exposed controls was achieved with 10 µM prilocaine. Prilocaine, in a dose-dependent manner, scavenged, radiation-induced hydroxyl radicals and maximally (43 %) at the highest concentration (1 mM) tried in this study. However, prilocaine exerted a mild superoxide anion scavenging potential (around 5 %) at all the concentrations used within this study. Prilocaine, at 20 µM concentration, significantly increased erythropoiesis, a marker for HSC function, in caudal hematopoietic tissue (CHT) in wild type and anemic zebrafish embryos (1.48 and 0.85 folds respectively) when compared to untreated (1) and phenylhydrazine (PHZ) (0.41 fold) treated control groups respectively. These results suggest that prilocaine is a radioprotective agent and free radical scavenging and HSC expanding potential seems to be contributing towards its radioprotective action.

Pharmacokinetic and pharmacodynamic evaluation of a nanotechnological topical formulation of lidocaine/prilocaine (nanorap) in healthy volunteers.

BACKGROUND: Nanorap is a new nanotechnological formulation for topical anesthesia composed of lidocaine (2.5%) and prilocaine (2.5%). This study evaluated the pharmacokinetics of Nanorap. For the determination of lidocaine and prilocaine in human plasma, a new method using high-performance liquid chromatography coupled with tandem mass spectrometry was developed. Nanorap pharmacodynamic (PD) and its physical proprieties were also evaluated. METHODS: Nanorap was administered by topical application of 2 g to healthy volunteers, and blood samples were collected for the pharmacokinetics analysis. The drugs were extracted from plasma by liquid-liquid extraction with ether/hexane (80/20, vol/vol). The chromatography separation was performed on a Genesis C18 analytical column 4 µm (100 × 2.1 mm i.d.) with a mobile phase of methanol/acetonitrile/water (40/30/30, for lidocaine, and 50/30/20, for prilocaine, vol/vol/vol) + 2 mM of ammonium acetate and ropivacaine as internal standard. The drugs were quantified using a mass spectrometer with an electrospray source in the electrospray ionization positive mode configured for multiple reaction monitoring. The PD of Nanorap was evaluated with the use of a visual analog scale. Nanorap was characterized by cryofracture. RESULTS: The chromatography run-time was 5.5 minutes for lidocaine and 3.3 minutes for prilocaine, and the lower limit of quantification was 0.05 ng/mL for both drugs. Mean Cmax was 6.62 and 1.72 ng/mL for lidocaine and prilocaine, respectively. Median Tmax was 6.5 hours for both drugs. Nanocapsules had a mean size of 88 nm and mean drug association of 92.5% and 89% for lidocaine and prilocaine, respectively. The PD study showed that Nanorap has a sufficient analgesic effect (>30% reduction in pain) after 10 minutes of application. CONCLUSIONS: A new simple, selective, and sensitive method for determination of lidocaine and prilocaine in human plasma was developed. Nanorap generated safe plasma levels of the drugs and satisfactory analgesic effect.

Comparison of the effects of low volume prilocaine and alkalinized prilocaine for the regional intravenous anesthesia technique in hand and wrist surgery.

AIM: Comparing the effectivity of prilocaine and prilocaine alkalinized with 8.4% NaHCO3 in terms of sensory and motor block onset and termination durations in RIVA technique considering patients' satisfaction and tolerance with application of tourniquet undergoing hand-wrist surgery. MATERIALS AND METHODS: 64 patients were randomised into two groups. First group (Group P) was administered prilocaine and second group (Group PN) was administered prilocaine + %8.4 NaHCO3. Sensory and motor block onset and termination times and onset of tourniquet pain were recorded. RESULTS: No significant difference was found between the two groups in terms of onset and termination of sensory block and the onset of motor block. The duration of the motor block was longer in Group PN than in Group P (P < 0.05). Tourniquet pain was more intense in Group P (P = 0.036). In Group PN, the use of additional drugs was recorded at a lower rate and patients' satisfaction was higher than Group P. CONCLUSION: In the present study, it was established that alkalinization of prilocaine had no effect on the duration of sensory block and it prolonged the duration of motor block, increased patients' satisfaction, and decreased tourniquet pain. It is our suggestion that future studies should be carried out on the issue by using different volumes.