A Comparative Study Using Dexmedetomidine and Clonidine as Adjuvants with Levobupivacaine in Axillary Brachial Plexus Block for Upper Limb Surgeries

Introduction: The axillary approach to the brachial plexus is the most popular because of its ease, reliability, and safety. Blockade occurs at the level of the terminal nerves. Alpha2-agonists are mixed with local anaesthetic agents to extend the duration of spinal, extradural and peripheral nerve blocks. The aim of the study is to compare the effects of clonidine and that of dexmedetomidine as adjuvants to levobupivacaine in axillary brachial plexus block. The onset time and duration of sensory and motor block, duration of analgesia, sedation score and haemodynamic parameters were studied in both groups. Methods: A prospective, double blinded, randomized clinical study was conducted at Department of Anaesthesia, Kamineni Academy of Medical Sciences and Research Center on eighty ASA class I and II adult patients undergoing upper limb surgeries under ultrasound guided axillary brachial plexus block. Patients were randomly divided into two equal groups, group LD (n=40): will receive 25ml of 0.5 % of levobupivacaine +1 μg/kg dexmedetomidine, and group LC (n=40) will receive 25ml of 0.5 % levobupivacaine +1 μg/kg of clonidine. The whole solution made up to 30 ml in each group by adding sterile water for injection. Haemodynamic parameters (heart rate, non invasive blood pressure, oxygen saturation), onset time and duration of sensory, motor block, duration of analgesia and, sedation score were recorded and then compared between the groups. Results: There was no statistically significant difference (P>0.05) in haemodynamic parameters. Onset time of sensory and motor block were significantly faster (P<0.05), duration of sensory and motor block and duration of analgesia significantly longer (P <0.05) in dexmedetomidine group (group LD) when compared to clonidine group (group LC). The sedation scores were also better in group LD (P<0.05). Conclusion: Dexmedetomidine is a better adjuvant than clonidine when added to levobupivacaine in axillary brachial plexus block, as it hastens the onset time of sensory and motor block, prolongs the duration of sensory and motor blockade as well as the duration of analgesia, with better intraoperative sedation without causing any haemodynamic variations

Rational Construction of Triazole/Urea Based Peptidomimetic Macrocycles as Pseudocyclo-β-peptides and Studies on Their Chirality Controlled Self-Assembly

A tandem macro-dimerization reaction via a Cu(I) catalyzed azide/alkyne cycloaddition reaction has been employed to construct triazole/urea based peptidomimetic macrocycles considered as pseudocyclo-β-peptides. Introduction of one particular chirality in the peptide backbone can alter the conformation as well as nature of self-assembly from cyclic D-,L-,α-peptide to cyclo-β-peptide. One of them (16a) forms antiparallel dimers while the other (16b) undergoes higher order aggregation to form a nanorod structure