SCREENING OF IQB-9302

SCREENING OF IQB-9302

SCIATIC NERVE BLOCK IN RAT

 

METHODS AND MATERIALS

Test Solutions:

IQB-9302 (Batch 93001) was provided by the sponsor and dissolved in distilled water to obtain 0.1% solutions. Mepivacaine was obtained from SCANDINIBSA (commercial solutions containing 1% mepivacaine) and diluted to 0.5% and 0.1% with distilled water All solutions were coded to provide blinding to the technician and investigator.  

Technique:

Sciatic nerve block in the rat was performed in the following manner:  

Male, Sprague-Dawley rats having an initial test weight of 200-300 grams were used. All animals were purchased from IFFA-CREDO. Upon arrival at the research facility, rats were divided into groups of 10 animals each. Each group was assigned a letter code A-C thus there were 3 groups of 10 rats each. Each of 10 rats was tested with one of the test solutions (mepivacaine 0.5%, mepivacaine 0.1% and IQB-9302, 01%). The animals were housed inside a barriered, limited access rodent facility. The animal room had its own supply of filtered air with controlled temperature (20 ± 2ºC) and humidity (55 ± 5%).  

The day of experiment, animals were anesthetized with sodium thiopental 50 mg/kg i.p. Tracheotomy was performed to maintain respiration and sciatic nerve was denuded in one of the hind legs. At least one cm long fragment of sciatic nerve was isolated from surrounding tissues to insert a stimulation electrode connected to an electric stimulator (SRI Mod 5063).  

Gastronecmic muscle was dissected and the distal end was connected through an appropriate device to an isometric transducer (UF1 Panlab) connected to a pen recorder (Omniscribe).  

The sciatic nerve was stimulated with a square pulse current of 1.5 volts and 30 milliseconds of amplitude.  

After 5 minutes of stabilization to obtain basal tone of each preparation, a small cotton swab was placed around the sciatic nerve and 100 ml of test solutions were added. The response of the sciatic nerve to stimulation was periodically recorded at 10 min intervals up to 2 hours after application of test solutions. Tests solutions were then washed out with saline and recovery of nerve transmission was recorded  

RESULTS

Application of 100 ml of mepivacaine 0.1% and 0.5% totally suppressed nerve conduction. When the preparations were washed with saline after 2 hours, recovery of nerve conduction was observed with mepivacaine 0.1%, whereas no response was observed after mepivacaine 0.5%.  

IQB-9302 0.1% totally inhibited nerve conduction and no recovery was observed after washing. On the other hand the onset on nerve blockade was more rapid with IQB- 9302 as shown in figure 2 that is representative of this set of experiments.  

Based on these experiments it can be concluded that IQB-9302 is at least 5 times more active than mepivacaine, being shorter the onset of anesthetic effect.