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A Comparative study of the Anticonvulsant effect of Nimodipine andKetamine combination with standardanticonvulsant drug in Rodents Prasanand S1, Pushpalatha C2, Mohsin MD3, Sam Pavan Kumar G4, Gundappa Rao S5 Aim of the study: To evaluate and compare the anticonvulsant property of nimodipine and
ketamine combination with a standard drug like Sodium valproate in electrically and chemically
1 Asst. Professor Department induced seizures in mice.
of Pharmacology,Vinayaka Mission's Medical Methods: The maximal seizure pattern was induced in mice by giving an alternating current of
College and Hospital, 50 mA for 0.2 sec, 50 Hz and 220 volts (maximal electroshock method), while tonic-clonic seizures were seen with 60mg/kg sc. dose of pentylenetetrazole (PTZ). The test drugs were administered 2, 4 Assoc. Professor 30min before electrical or chemical induction. The ability of the test drug to abolish or reduce tonic-clonic seizures is taken as antiepileptic criteria. The dose of the test drugs nimodipine was Department of Pharmacology, kept constant and combined with increasing dose of ketamine.
Chalmeda Anand Rao Institueof Medical Sciences, Results: In maximal electroshock (MES) method, nimodipine (5mg/kg) in combination with
ketamine (50mg/kg) only at a higher dose abolished tonic-clonic seizures. In pentylenetetrazole (PTZ) induced method, nimodipine (5mg/kg) in combination with ketamine at doses of 30, 50 Amirtha School of Ayurveda mg/kg abolished seizures.
Kollam, Kerala.
Conclusion: The result suggests that nimodipine and ketamine combination was effective
against maximal electroshock (MES) induced seizures in animals. This is the best validated model
for evaluating drugs for the treatment of generalized tonic-clonic seizures (GTCS) in human. The 1Dr. S. Prasanand combination is also effective against pentylenetetrazole (PTZ) induced seizure in animals and MD (Pharmacology) may be effective in absence seizure in human.
KEYWORDS: Nimodipine, ketamine, pentylenetetrazole (PTZ), maximal electroshock (MES)
methyl-D-aspertate (NMDA) receptor antagonist may have effective action in blocking seizures since N-methyl-D- Epilepsy is one of the most common serious primary brain aspertate (NMDA) receptors activate the voltage sensitive disorders, affecting 40 million people worldwide(1). It is a calcium channels. Maximal electroshock (MES) method is heterogeneous symptom complex-a chronic disorder the measure of the ability of an anticonvulsant drug to abolish characterized by recurrent seizures. Seizures are finite or decrease in the duration of fore limb flexion or hind limb episodes of brain dysfunction resulting from abnormal extension was taken as an index of protection induced my discharge of cerebral neurons.The term epilepsy refers to a means of an Electroconvulsometer(3). Maximal electroshock group of chronic neurologic conditions characterized by (MES) seizures and Pentylenetetrazole induced seizures are recurrent epileptic seizures. Epileptic seizures are the clinical the widely used evaluation methods for substances with manifestations (signs and symptoms) of excessive and /or potential antiepileptic activity.
hypersynchronous, usually self-limited, abnormal activity of neurons in the brain(2). Some epileptic seizures may be primarily generated at a subcortical level.
MATERIALS AND METHODS
As calcium ion influx is involved in the origin of seizures, a The anticonvulsant profile of nimodipine and ketamine calcium channel blocker like Nimodipine has vital role as an combination was evaluated in two conventional antiepileptic drug and the combination with Ketamine, a N- experimental methods of epilepsy; (i) Pentylenetetrazole Journal of Chalmeda Anand Rao Institute of Medical Sciences Vol 5 Issue 1 November 2012 ISSN (Print) : 2278-5310 Prasanand etal : A comparative study of the anti convulsant effect of nimodipine and ketamine (PTZ) induced convulsions, (ii) Maximal electroshock (MES) in each group. Control group received Distilled water, 0.5ml/ mice, Standard group received Sodium valproate, 150mg/ kg., Test 1, 2 and 3 groups received Nimodipine 5mg/kg in Animals: Sixty male albino mice weighing between 24 to 40
combination with Ketamine 10mg/kg, 30mg/kg and 50mg/ grams were used. Mice were kept in groups of 3 to 4 per kg, intraperitoneally, respectively. After 30 minutes of cage and fed regularly except during test period. The study administration of control, standard and test drug Maximal was approved by Institutional Animal Ethics Committee electroshock given to induce convulsions. An ear-clip (IAEC). Experiments were carried out at around the same electrode was used to deliver the stimuli with the current time every day.
strength of 50 mA for 0.2 sec, 50 Hz and 220 volts(6). The Drugs: Nimodipine (5mg/kg, ip)5, Ketamine (10, 30 & 50
experimental animals were closely observed for 5 minutes mg/kg, ip) were dissolved in distilled water and and the following parameters were recorded(7).
administered in combination, Pentylenetetrazole (PTZ) - Duration of clonic flexion phase (60mg/kg, sc).
- Duration of tonic extension phase i) Pentylenetetrazole (PTZ) induced convulsions in mice: Thirty male mice were divided into 5 groups consisting of - Duration of post-ictal depression phase six mice in each group. Control group received Distilled water, 0.5ml/mice, Standard group received Sodium - Time of recovery valproate, 150mg/kg., Test 1, 2 and 3 groups received Nimodipine 5mg/kg in combination with Ketamine 10mg/ kg, 30mg/kg and 50mg/kg, intraperitoneally, respectively.
Pentelenetetrazole (PTZ) 60mg/kg injected, subcutaneously, i) Pentylenetetrazole (PTZ) Induced Convulsios in Mice after 30 minutes of administration of control, standard and test drug. Each animal was placed in individual plastic cage Control group (Distilled water 0.5ml/mice): All animals and observed for 1 hour for time of onset, duration of developed clonic tonic convulsion by PTZ. The mean time convulsion, time to recover(4).
of onset of convulsion was 653.6 ± 179.04 seconds, mean duration of convulsion was 12.33 ± 4.3 seconds and mean ii) Maximal electroshock (MES) induced convulsions: Thirty time of recovery was 214.33 ± 108.38 seconds. All animals male mice were divided into 5 groups consisting of six mice Effect of Drugs on Pentylenetetrazole (PTZ) Induced Convulsios in Mice Mean time of onset of convulsion (sec) Distilled water 0.5ml/mice Sodium valproate 150mg/kg 2289.83 ± 408.49** Nimodipine 5mg/kg + Ketamine 10mg/kg Nimodipine 5mg/kg + Ketamine 30mg/kg Nimodipine 5mg/kg + Ketamine 50mg/kg Mean values represented as Mean ± S.D.
n = 6 in each group *P < 0.05 – Significant, **P < 0.001 – highly Significant Journal of Chalmeda Anand Rao Institute of Medical Sciences Vol 5 Issue 1 November 2012 Prasanand etal : A comparative study of the anti convulsant effect of nimodipine and ketamine Effect of Drugs on Maximal Electroshock (MES) Induced Convulsions in Mice Mean duration of hind Mean duration of Post- forelimb flexion (sec) limb extension (sec) ictal depression (sec) Distilled water 0.5ml/mice Sodium valproate 150mg/kg 13.33 ± 20.695** 23.67 ± 36.713** Nimodipine 5mg/kg + Ketamine 10mg/kg Nimodipine 5mg/kg + Ketamine 30mg/kg Nimodipine 5mg/kg + Ketamine 50mg/kg Mean values represented as Mean ± S.D n = 6 in each group *P < 0.05 – Significant, **P < 0.001 – highly Significant experienced one episode of convulsion and no mice died.
significant in duration of onset and time of recovery i.e., P< Standard group (Sodium valproate 150mg/kg): On administration of standard drug, the mice remained normal ii) Maximal Electroshock (MES) Induced Convulsions in Mice and no animal developed convulsion in one hour observation after PTZ administration. One mouse showed minimal Control group (Distilled water 0.5ml/mice): All animals twitching for 4 seconds. It was inferred as 100% protection developed single episode of convulsion after MES with mean against convulsion.
duration of forelimb flexion of 4.167 ± 1.169 seconds, mean duration of hind limb extension of 26.67 ± 7.340 seconds, Test - 1 group (Nimodipine 5mg/kg + Ketamine 10mg/kg): mean duration of post-ictal phase of 75.67 ± 16.367 seconds All animals developed convulsion after PTZ administration and mean duration of recovery of 115.67 ± 36.098 seconds.
with a mean time of onset of 2289.83 ± 408.49 seconds, mean duration of convulsion of 7.67 ± 1.967 and mean duration of Standard group (Sodium valproate 150mg/kg): On recovery of 12.83 ± 3.060 seconds which implies that all events administration of standard drug, no mice developed occurred after a prolonged period when compared to control convulsion after MES. Three mice showed a minimal twitching and a jerky movement. It implies that 100% protection was offered against convulsion.
Test - 2 Group (Nimodipine 5 mg/kg + Ketamine 30mg/ kg): The mice were monitored for one hour after PTZ Test - 1 group (Nimodipine 5mg/kg + Ketamine 10mg/kg): administration. 4 out of 6 mice had tail rising whereas 2 mice Only three mice developed clonic convulsion of which one had a minimal twitch and no mice developed convulsion. In mice did not show tonic convulsion with mean duration of this group 100% protection was provided by test drug.
forelimb flexion of 0.833 ± 0.983 seconds, mean duration of hind limb extension of 13.33 ± 20.695 seconds, mean duration Test - 3 Group (Nimodipine 5 mg/kg + Ketamine 50mg/ of post-ictal phase of 4.33 ± 6.743 and mean time of recovery kg): All animals were protected (100%) from convulsions and of 23.67 ± 36.713 seconds.
no jerks or twitches were observed. The mice looked normal and active and the test dose was effective.
Test - 2 Group (Nimodipine 5mg/kg + Ketamine 30mg/kg): It was observed that 2 out of 6 mice developed convulsion From the findings there was 100% protection from after MES with mean duration of forelimb flexion of 0.667 ± convulsions in standard group and also in Test - 2 and Test - 0.968 seconds, mean duration of hind limb extension of 1.167 3 groups. On comparison of Test groups with control group, ± 1.835 seconds, mean duration of post-ictal phase of 2.83 ± Test – 1, Test – 2 and Test - 3 were statistically highly 4.401 seconds and mean duration of recovery of 3.833 ± 5.947 Journal of Chalmeda Anand Rao Institute of Medical Sciences Vol 5 Issue 1 November 2012 Prasanand etal : A comparative study of the anti convulsant effect of nimodipine and ketamine seconds which implies that all events occurred after a day orally for five days, increased the seizure - threshold by prolonged period when compared to control group.
50-60% in rabbits.
Test - 3 Group (Nimodipine 5mg/kg + Ketamine 50mg/kg): The efficacy of calcium channel blockers (CCBs) to reduce no mice developed convulsion. Only 1 out of 6 mice was the duration of tonic hind limb extensor phase in the MES observed with minimal twitches. In this group 100% has been shown to correlate with the ability to prevent partial protection was offered by test drug.
and generalized tonic clonic convulsions in man(9).
Theoretical consideration suggests that CCBs have From the values recorded, the control group had 0% and anticonvulsant activity and this work correlates with the standard group had 100% protection from MES induced earlier studies(10). These drugs have important potentials as convulsions. On comparison of test groups with control adjuvants and as non-sedative antiepileptic agents(11).
group, Test - 1 was statistically highly significant (P<0.001) in duration of hind limb extension. Test – 1 was highly The combined anticonvulsant activity may be due to the L- significant and Test - 2 was significant (P < 0.05) in post-ictal type Ca2+ channel blockade by Nimodipine and non- phase. All test groups were highly significant (P < 0.001) in competitive antagonism of NMDA receptor by Ketamine.
relation to the time of recovery. The combination of Ketamine has also been reported to inhibit voltage dependent Nimodipine with Ketamine at a higher dose (50mg/kg) was Ca2+ channels(12). In nerve cells, it has been shown that effective against both PTZ and MES induced convulsions in stimulation of NMDA receptor, activates voltage operated experimental mice.
Ca2+ channels(13) and Nimodipine has been reported to counteract the increased Ca2+ influx evoked by NMDA receptors(14). Furthermore, Nimodipine has also been shown to decrease Ca2+ dependent release of excitatory The result of this study indicated that the dihydropyridine calcium channel blocker Nimodipine has shown to be In conclusion, all the observations and the findings in this effective against Pentylenetetrazole (PTZ) and Maximal Electro shock (MES) induced convulsions when given in experiment suggest that the anticonvulsant effect of the combination of Nimodipine and Ketamine is comparable to combination with Ketamine, a non-competi-tive antagonist that of the standard drug, Sodium valproate. This indicates of NMDA receptors in mice. NMDA receptors have been proposed to be involved in the generation and maintenance that, Nimodipine and Ketamine combination was effective against MES induced seizures in animals. This is the best of epileptiform activity. Earlier studies have indicated that validated model for evaluating drug for the treatment of NMDA receptor antagonists more effectively block or antagonize the Maximal Electroshock (MES) induced GTCS in human. The combination is also effective against PTZ induced seizure in animals and may be effective in seizures and they are either ineffective or weak against Absence seizure in human.
Pentylenetetrazole (PTZ) or Picrotoxin induced seizures in The present study is based on the combined effect of Nimodipine and Ketamine when compared to the standard On the basis of present study, it can be stated that antiepileptic drug against Pentylenetetrazole (PTZ) and Nimodipine 5mg/kg in combination with Ketamine 10mg/ Maximal ElectroShock (MES) induced convulsions in kg was not effective but with Ketamine 30mg/kg and 50mg/ experimental mice. Nimodipine 5 mg/kg bodyweight is kg had 100% protection which is similar to that of sodium given in combination with Ketamine in doses of 10mg/kg, valproate 150mg/kg in controlling seizures induced by 30mg/kg and 50mg/kg bodyweight. It has shown that this Pentylenetetrazole. Nimodipine 5mg/kg with Ketamine at combination reduced the duration of flexor and extensor the doses of 10mg/kg, 30mg/kg and 50mg/kg had 50%, 67% phases as well as incidence of convulsions in both PTZ and and 100% protection against Maximal Electroshock induced MES induced convulsions. The study showed that Ketamine convulsion in mice. On comparison with Sodium valproate, produced dose related anticonvulsant effect when given with Nimodipine 5mg/kg + Ketamine 10mg/kg and 30mg/kg Nimodipine 5mg/kg bodyweight. The anticonvulsant effects were comparatively less effective, whereas Nimodipine were significant (P <0.01) with Nimodipine 5mg/kg + 5mg/kg + Ketamine 50mg/kg was equally effective, in Ketamine 30mg/kg. It was highly significant (P <0.001) with controlling seizures induced by Maximal electroshock in Nimodipine 5mg/kg + Ketamine 50mg/kg which blocked mice. It may be concluded that Nimodipine and ketamine the flexor and extensor phases. This is in agreement with the combination has anticonvulsant effect; an increase in findings of Irfuno et al(8) who observed that NMDA induced anticonvulsant effect was observed when the dose of hyperactivity was antagonized by Ketamine in a dose- Ketamine was increased in combination with Nimodipine.
dependent manner. In a study done by Meyer et al, had stated that Nimodipine when administered in a dose of 5mg/kg/ Journal of Chalmeda Anand Rao Institute of Medical Sciences Vol 5 Issue 1 November 2012 Prasanand etal : A comparative study of the anti convulsant effect of nimodipine and ketamine Irfuno M, et al. N-Methyl-D-aspartate (NMDA) receptors in non- competitive NMDA receptor antagonist-induced hyperlocomotion in The authors are grateful to the Department of Pharmacology mice, Pharmacol Biochem Behav . 1995; 51: 291 - 296.
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Journal of Chalmeda Anand Rao Institute of Medical Sciences Vol 5 Issue 1 November 2012

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