Freeze-drying of bupivacaine lipospheres: preparation, characterization, and evaluation of anti-microbial properties.

PURPOSE: To prepare freeze-dried bupivacaine lipospheres intended for topical application in burn injuries. The aim was improving the storage stability and developing a prolonged release pattern to tackle the adverse reactions resulting from the frequent administration of bupivacaine. METHODS: The lipospheres were prepared by hot-melt dispersion method employing bupivacaine base at 1.5 and 3%w/w, tristearin 6% w/w as the core while dipalmitoyl phosphatidylcholine (DPPC) and soy phosphatidylcholine (SPC) as the coat at 0.75, 1.5 and 3% w/w. The lotion was then freeze-dried and cryoprotected by sucrose 3% w/w. Evaluation was carried out through loading and release analysis, storage study, particle characterization including morphology, zeta potential and particle size as well as anti-microbial assessment. RESULTS: The highest loading, (87.6 ± 0.1%), was achieved using bupivacaine 3% and SPC 0.75%. After 6 months of storage at 4 ͦC, the loading in the lotion and the freeze-dried samples were 17.4 ± 0.2 and 87.2 ± 0.3%, respectively. In vitro dissolution test demonstrated 94.5% and 95% of bupivacaine release from lotion and freeze-dried samples, after 24 h. The respective zeta potential of -1.30 and 26 mV was recorded for lotion and solid-state bupivacaine. Micromeritic evaluation of freeze-dried powder exhibited particle size of 35.23 ± 2.02 µm and highly-wrinkled-irregular morphology without detectable needle structures related to drug free crystals. The powder had rapid reconstitution property and antibacterial activity. CONCLUSION: Freeze- drying holds a promising potential to improve the storage stability of bupivacaine lipospheres with well- preserved release pattern and particle properties for further topical application.

Efficacy of Low-Frequency Electroacupuncture on Urinary Retention After Spinal Anesthesia.

PURPOSE: This study was designed to evaluate the efficacy of low-frequency electroacupuncture (EA) in the prevention of urinary retention after orthopedic surgery. DESIGN: A double-blind placebo-controlled clinical trial. METHODS: Eighty patients with spinal anesthesia were randomly allocated into the groups of EA (40 cases) and control (40 cases). In the first group, the EA was applied to four points of SP6, SP9, ST28, and CV2; 4 Hz, retaining for 20 minutes in the postanesthesia care unit (PACU). In the control group, no intervention was applied. The incidence of postoperative urinary retention, incomplete or difficult urination, and the first automatic micturition time since spinal anesthesia were compared between the two groups. FINDINGS: The incidence of urinary retention and incomplete urination in the EA group was significantly lower than that in the control group; the time to first urination was shorter in the intervention group than in the control group (P < .05). CONCLUSIONS: Electroacupuncture after spinal anesthesia improves bladder function and reduces the need for a urinary catheter and its possible complications.

Efficacy of a Modified Bier's Block in Patients Undergoing Upper Limb Bone Surgery.

BACKGROUND: Intravenous regional block, called the Bier's block, refers to an analgesic technique applied for soft tissue surgeries and closed bone manipulations of the limbs. There are a number of complications in traditional method of block, including pain in tourniquet site, immediate return of pain after tourniquet deflation, wound hemostasis and some others. OBJECTIVES: The aim of this study was to assess the outcomes and complications of our new method of blockage. PATIENTS AND METHODS: In this experimental study, twenty-five patients undergoing hand surgery were prospectively studied. Induced anesthesia was a modification of the Bier's block with two concurrent changes including insertion of the intravenous cannula at the antecubital region rather than distal and the proximal anesthetic direction by an elastic band wrapped tightly around the proximal forearm distal to the cannulation site. The pain relief was measured by the verbal descriptive scale at intervals after block, during the operation, after deflation of the tourniquet and one hour after the operation. RESULTS: This study showed the presence of analgesia at surgical and tourniquet sites during the operation in 96% of patients, as well as considerable pain relief at surgical site during one hour after deflation of the tourniquet. CONCLUSIONS: The study indicated advantages of this modified Bier's block compared to the traditional one including ability to perform surgery on upper limb bones and considerable pain relief at surgical and tourniquet sites during the operation until one hour thereafter.