1、Anticonvulsant Effects of Drugs XXX （China Pharmaceutical University，639 Longmian Avenue, Nanjing, Jiangsu, China 210009） ABSTRACT: OBJECTIVE: To study the anticonvulsant efficacy of Phenytoin sodium and Phenobarbital and valproate on convulsion. METHODS: The anticonvulsant activity of the drugs was
2、 evaluated by the maximal electroshock (MES) test and remeflin seizure test. Induced rats were treated by intraperitoneal injection ,then observe the incubation period (up to tails upright 45) and degree of reaction of each mouse(spasm, falling down ,stiff or death). RESULTS: 1. In MES experiment, t
3、he degree of convulsion: The Phenobarbital group (P0.05 vs normal saline group) was the lightest, and the NS group was the severest one. 2. In remeflin experiment, the similar result was observed between valproate group and NS group (P0.01). CONCLUSION: Phenobarbital has better anti-convulsion effec
4、t than Phenytoin sodium on convulsion induced by electroshock, and valproate has a significant effect to anti-convulsion induced by remeflin. KEYWORDS Phenytoin sodium; Phenobarbital; valproate; remeflin ; anti-convulsion Introduction Phenytoin sodium: its mechanism of action: It can block sodium ch
5、annels (voltage-, frequency-, and time dependent fashion) and inhibit the generation of action potentials and It can increase the function of inhibitory transmitter GABA, inhibit nerve terminal to uptake GABA and induce the increasing of GABA receptor, thereby enhance GABA-mediated postsynaptic inhi
6、bition. Phenobarbital: its mechanism of action: Phenobarbital can inhibit the paradoxical discharge of epilepsy focus selectively, enhance stimulation of surrounding tissues and block discharge diffuse to normal tissues and Phenobarbital facilitate GABA-mediated inhibition of neuronal activity. Valp
7、roate is broad spectrum antiepileptic drug, which is used to all types of epilepsy; its mechanism is that enhancing the enzymatic activity of glutamate decarboxylase. And Inhibiting GABA reuptake and synapse inactivation via releasing synapse frontal membrane GABA and then enhance GABA postsynaptic
8、inhibition Remeflin, a central stimulate which can directly excite respiratory center, can produce convulsion with over-dose. The protective effects of drugs on convulsion produced by remeflin can be used to screen antiepileptic and anti-convulsion. Stimulating mouse head with a strong electric curr
9、ent can cause general tetanic convulsion. If a drug can prevent the occurrence of general titanic convulsion, we could initially suspect that it has antagonistic effect on grand mal. Remeflin, a central stimulant which can directly excite respiratory center, can protective effects of drugs on convul
10、sion produced by remeflin can be used to screen antiepileptics and anticonvulsants. 1 1 Material Equipments Balance, syringes, pharmacological and physiological multipurpose apparatus Reagents Phenytoin sodium, 0.5% solution w/v, Phenobarbital sodium, 0.5% solution w/v, 0.04% Remeflin, 2% sodium val
11、porate, normal saline Animals 5mice, 18-22g, no restriction on sex 2 Methods 2.2 Methods of MES experiment Adjust the stimulator firstly. Stimulating parameters: working condition- electric shock; output voltage-maximum; model of stimulating-single; frequency- 3216Hz; connect the outlet with clips a
12、nd plug the connection for power. Select convulsion mice. Attach the clips moistened with saline to the mouse ears. Punch the key to starting, and a current is applied to the head of the mouse, then cause tonic convulsion that is the state of the flexing forelimb and straightening hind limb. If the
13、animals dont fall into convulsion with 32Hz, modulate to 16Hz, and start again. Replace another one to test if have no reaction, yet. Select three mice in which convulsions occur typically. Mark and weigh them. Treat them by intraperitoneal injection of 5% phenytoin sodium 75mg/kg (0.15ml/10g), 5% p
14、henobarbital sodium 75mg/kg (0.15 ml/10g) and normal saline 0.15 ml/10g separately. 40 minutes after injection, stimulate the mice again with pro- threshold. Record the response. 2.2 Methods of remeflin experiment Mark and weigh two mice. Treat them separately by intraperitoneal injection of 2% sodi
15、um valproate 600mg/kg (0.3ml/10g) and normal saline 0.3ml/10g. 30 minutes after administration, inject them with remeflin 8mg/kg (0.2ml/10g) subcutaneously. Observe the speed and degree of reaction of each mouse (spasm, falling down, stiff or death). 2.3 Statistic method and intensity measures Stati
16、stic methods: Experimental data in each groups were expressed by xs in the experiment used remeflin, analysis of variance and t-test (One-way Analysis of Variance, ANOVA) in the intergroup analysis , analysis of the intensity degree (Rank- Sum-Test ) results and analysis of rate by 2 test (Fishers e
17、xact test) were applied statistical software SPSS 19.0, significant level =0.05. Outcome measures on behaviors in remeflin induced convulsion model: degree 0: no phenomenon; degree 1: tails upright; degree 2: tumble; degree 3: stiff; degree 4: death. 3 Results 3.1 Results of MES experiment Phenobarb
18、ital was obvious to have the protective effects on MES convulsion (P0.05 vs Normal saline), and it is better than phenytoin sodium which has a weak anticonvulsant effiancy that the convulsion rate was between normal saline group and Phenobarbital group. Table 1 result of protective effects on MES co
19、nvulsion of phenytoin sodium and phenobarbital. Drugs Dosage（mg/kg） Convulsion/Sum Convulsion Rate(%) Normal saline 6/8 75 Phenobarbital 75 1/8 12.5* Phenytoin sodium 75 4/8 50 *P0.05 vs Normal saline 3.2 Result of remeflin experiment There was highly significant difference (P0.01) between the sodiu
20、m valproate group and normal saline group in death rate, and significant difference (P0.05) between the two groups in convulsion incubation and reaction intensity. This means that sodium valproate has the anticonvulsant efficacy to play a protective effects on the convulsant induced by remeflin. Aft
21、er injection of remeflin, mice may experienced incubation period, stiff flexion phase, straighting hind limb phase, clonic phase and restoration period. The mice in normal saline group behavior as follows: walked haltingly, jumped, uplifted fore limbs and stood on two feet, ears towards the back, an
22、d tails upwards like letter C. The mice in sodium valproate group behavior as: Walked slowly and the tail was almost straight up. The whole body shaked, and after several minutes its hind limbs were stiff, and died. Table 2 the results of effects of sodium valproate on convulsion produced by remefli
23、n (xs, n=8) Group Incubation (s) Death Time (s) Death Number Death Rate (%) Normal Saline 4.181.18 No death 0 0 Sodium Valproate 8.242.54* 7.680.80 # 6 75 * *P0.01 vs Normal Saline group; * P0.01 vs Normal Saline group # except 2 mice that didnt die Table3 the reaction intensity degree on mice convu
24、sion produced by remeflin Group Reaction Intensity(Degree) Num 1 2 3 4 5 6 7 8 Normal Saline 4 3 4 4 4 1 4 4 Sodium Valproate* 1 1 2 1 1 1 1 1 *P0.01 VS Normal Saline Group 4 Discussions Because of individual difference of animals, stimulating parameters should be set with experiment. Dont set it ov
25、er-strong, in order to prevent animals from death. Prevent short circuit of clips carefully, otherwise the stimulator would be damaged. The convulsion of animals can be divided in five phase, latent period, stiff flexion phase, straightening hind limb phase, clonic phase and restoration period. If c
26、ondition permits, pentetrazole is recommended to be substituted for remeflin because the convulsion caused by pententrazole is more typical. 5 Conclusions Both Phenobarbital and phenytoin sodium have the protective effects on electric shock convulsion. And Phenobarbital whose effect is obvious has b
27、etter anti-convulsion effect than phenytoin sodium whose effect is weak respectively on convulsion induced by electroshock. And valproate has a significant effect to anti-convulsion induced by remeflin, while remeflin can kill the most of the mice in experiment and valproate can reduce the toxicity of remeflin. Reference 1 Peng Xiaodong, et al Anticonvulsant efficacy of Chinese Materin Medicine Cynanchum Chinese R.Br in mice J J Fourth MilMed Univ 2009,30 (4):340-344
