Smart needle electrical bioimpedance to provide information on needle tip relationship to target nerve prior to local anesthetic deposition in peripheral nerve block (USgPNB) procedures.

Ultrasound guided peripheral nerve block (USgPNB) refers to anaesthetic techniques to deposit local anesthetic next to nerves, permitting painful surgery without necessitating general anesthesia. Needle tip position prior to local anesthetic deposition is a key determinant of block success and safety. Nerve puncture and intra-neural injection of local anesthetic can cause permanent nerve injury. Currently ultrasound guidance is not sufficiently sensitive to reliably detect needle to nerve proximity. Feedback with bioimpedance data from the smart needle tip might provide the anesthetist with information as to the relationship between the needle tip and the target nerve prior to local anesthetic deposition. Bioimpedance using a smart needle integrated with a two-electrode impedance sensor has been developed to determine needle to nerve proximity during USgPNB. Having obtained all necessary ethical and regulatory approvals, in vivo data on brachial plexus, vagus, femoral and sciatic nerves were obtained from seven pig models using the smart needle bioimpedance system. The excision and histological analysis of above peripheral nerves and observation of the architecture and structure of nerves by means of histology allow the calculation of the ratios of connective tissue to neural tissue to determine the influence of this variable on absolute impedance. The ratio results give extra clinical data and explain the hetrogeneity of impedance data in the pig models and the hypothesis that connective tissue with intra-neural fat has higher impedance than neural tissue.

Sounding out stability of enteric coated dosage forms using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS).

Stability testing is essential in the pharmaceutical industry to determine product shelf- life and the conditions under which drug products should be stored. Stability testing involves a complex set of procedures, considerable cost, time, and scientific expertise to build quality, efficacy and safety in a drug formulation. This paper highlights a new complementary approach to stability testing called Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS). BARDS measurements are based on reproducible changes in the compressibility of a solvent during dissolution. It is monitored acoustically via associated changes in the frequency of induced acoustic resonances. This study presents a novel approach to track the change of various drug formulations to determine the formulation's stability. Pellets, tablet and multiple-unit pellet system (MUPS) formulations were investigated to examine the effect of polymer coating and formulation core degradation over time. In combination with minimal usage of Ultra Violet - Visible Spectroscopy, BARDS can effectively track these changes. The technique offers a rapid approach to characterizing pharmaceutical formulations. BARDS can enable rapid development of solid drug formulation dissolution and disintegration testing as an In-Process Control test and drug stability analysis. The data show that a solid oral dose formulation has an intrinsic acoustic signature specific to the method of manufacture, excipient composition and elapsed time since the production of a product. BARDS data are also indicative of which aspect of a formulation may be unstable, whether a coating, sub-coating or core. It is potentially a time-efficient, cost-effective and greener approach to testing coating stability, disintegration and overall formulation stability.

The sound of tablets during coating erosion, disintegration, deaggregation and dissolution.

This research aims to address a gap in our understanding of the mechanisms by which pharmaceutical tablets achieve highly reproducible and predictable drug release. The present industrial and regulatory practice is centred around tablet dissolution, i.e. what follows disintegration, yet the vast majority of problems that are found in formulation dissolution testing can be traced back to the erratic disintegration behaviour of the medicinal product. It is only due to the distinct lack of quantitative measurement techniques for disintegration analysis that this situation arises. Current methods involve costly, and time-consuming test equipment, resulting in a need for more simple, green and efficient methods which have the potential to enable rapid development and to accelerate routine solid drug formulation dissolution and disintegration testing. In this study, we present a novel approach to track several sequential tablet dissolution processes, including coating erosion, disintegration, deaggregation and dissolution using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS). BARDS, in combination with minimal usage of UV spectroscopy, can effectively track these processes. The data also show that a solid oral dose formulation has an intrinsic acoustic signature which is specific to the method of manufacture and excipient composition.

A rapid in-process control (IPC) test to monitor the functionality of taste masking polymer coatings using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS).

Monitoring of the coating end-point of functional coatings during the coating application process is desirable. Since currently available PAT methods require expensive test equipment, there is a need for a rapid test that can easily be applied without major investment. BARDS is a novel technique that has the potential to economise the production process of these kinds of pellet and tablet formulations. The thickness of a controlled release coating is a key factor that determines the release rate of the drug in the gastro-intestinal tract or other targeted functionalities such as taste masking or moisture protection. Correspondingly, the amount of drug per unit mass of pellets decreases with increasing thickness of the functional coating. In this study, the functional polymer loading of the coating process is investigated by testing pellets via BARDS technology (Broadband Acoustic Resonance Dissolution Spectroscopy). The technique offers a rapid approach (<200 s) to characterising functional coatings at-line during their manufacture. Measurements are based on reproducible changes in the compressibility of a solvent during dissolution which is monitored acoustically via associated changes in the frequency of induced acoustic resonances. In case of enteric coatings a steady state acoustic lag time is associated with the erosion of the enteric coatings in acidic dissolution test media. This lag time is indicative of the coating layer thickness, assuming that the quality of the film coating is high. BARDS represents a possible future surrogate test for IPC testing, as a PAT method and possibly also for conventional USP dissolution testing. BARDS data correlate directly with the thickness of the functional coating, its integrity and also with the drug loading as validated by UV-Vis spectroscopy.