An Experimental Design Approach to Selecting the Optimum LC Conditions for the Determination of Local Anaesthetics

OUP accepted manuscript

BACKGROUND

Proparacaine hydrochloric ophthalmic solution (0.5%) is widely used as ophthalmic anesthetic for short conjunctival and corneal procedures. In connection to this, present research work was conducted to investigate ocular toxicity of its probable degradation products (DPs), which were generated after treating drug with stressors mentioned under International Conference on Harmonization (ICH) guideline Q1A (R2).

RESULT

The probable DPs were generated by placing drug under various stress conditions to generate similarity of the effect of stressor which drug supposed to face during its life cycle. The hydrolytic stress condition under acidic, basic and neutral environment formed two major DPs, while the drug was stable and did not generate any DP when subjected to oxidative, dry heat and photolytic stress. The separation of DPs was carried out using high performance liquid chromatographic system. The structural identification of DPs was carried out by subjecting degradation samples to liquid chromatography coupled with mass spectrometry. These DPs were screened using in-silico ocular toxicity prediction models Pub-SVM to predict their potential to cause irritation/corrosion to eye.

CONCLUSIONS

The DPs identified were DP 1 (2-(diethyl amino) ethanol) and DP 2 (3-amino-4-propoxybenzoic acid). The in-silico ocular toxicity study predicted that DP 1 has potential of eye corrosion (EC) and eye irritation (EI), whereas DP 2 has a potential EI. The drug was found safe and devoid of any EC and EI potential.

Hierarchical Thin Film Architectures for Enhanced Sensor Performance: Liquid Crystal-Mediated Electrochemical Synthesis of Nanostructured Imprinted Polymer Films for the Selective Recognition of Bupivacaine

Nanostructured bupivacaine-selective molecularly imprinted 3-aminophenylboronic acid-p-phenylenediamine co-polymer (MIP) films have been prepared on gold-coated quartz (Au/quartz) resonators by electrochemical synthesis under cyclic voltammetric conditions in a liquid crystalline (LC) medium (triton X-100/water). Films prepared in water and in the absence of template were used for control studies. Infrared spectroscopic studies demonstrated comparable chemical compositions for LC and control polymer films. SEM studies revealed that the topologies of the molecularly imprinted polymer films prepared in the LC medium (LC-MIP) exhibit discernible 40 nm thick nano-fiber structures, quite unlike the polymers prepared in the absence of the LC-phase. The sensitivity of the LC-MIP in a quartz crystal microbalance (QCM) sensor platform was 67.6 ± 4.9 Hz/mM under flow injection analysis (FIA) conditions, which was ≈250% higher than for the sensor prepared using the aqueous medium. Detection was possible at 100 nM (30 ng/mL), and discrimination of bupivacaine from closely related structural analogs was readily achieved as reflected in the corresponding stability constants of the MIP-analyte complexes. The facile fabrication and significant enhancement in sensor sensitivity together highlight the potential of this LC-based imprinting strategy for fabrication of polymeric materials with hierarchical architectures, in particular for use in surface-dependent application areas, e.g., biomaterials or sensing.