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The intravenous pentylenetetrazol (i.v.PTZ) seizure test provides threshold dose for induction of seizures in individual animals. In the present study, the i.v. and s.c.PTZ seizure models in mice were compared for seizure pattern, intra- and interanimal variability. Anticonvulsant activities of several antiepileptic drugs (AEDs) at non-ataxic dose levels were evaluated in the PTZ and maximal electroshock (MES) seizure tests. In the i.v.PTZ test, at 0.5 ml/min rate of administration, the mean threshold PTZ doses for induction of clonus and tonic extensor were 44.17 and 99.59 mg/kg, respectively. The intra- and interanimal variabilities in the seizure response were low in the i.v.PTZ as compared to the s.c.PTZ model. Phenobarbital sodium, ethosuximide, sodium valproate, diazepam, tiagabine, oxcarbazepine and zonisamide enhanced threshold or onset latency for clonus in the i.v. and s.c.PTZ tests, respectively. Levetiracetam and pregabalin were active in the i.v.PTZ test, but had no effect in the s.c.PTZ test. Ability of AEDs to protect from tonic extensor was compared in the MES and i.v.PTZ tests. For this effect, phenobarbital sodium, phenytoin, carbamazepine, sodium valproate, gabapentin, oxcarbazepine, zonisamide and pregabalin were effective in the i.v.PTZ and MES tests. Ethosuximide, diazepam and levetiracetam were effective in the i.v.PTZ test, but not the MES test. On the contrary, lamotrigine and topiramate were active in the MES, but not the i.v.PTZ test. These results indicate that it is advantageous to use i.v.PTZ test as an acute seizure model for screening of antiepileptic drugs. This model can identify molecules with varied mechanism of action and broad clinical utility in the treatment of epilepsy.

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Background: The anti-inflammatory potential of antihistamines has significant clinical utility. Long-term pharmacotherapy of so-called ‘safe’ antihistamines may be hampered by side effects in the central nervous system. In the present study, the new potential antihistamine SUN-1334H was compared with different antihistamines for anti-inflammatory effects, sedation potential and interaction with alcohol. Method: Nasal and skin allergy were induced in guinea pig and mice by ovalbumin sensitization and challenge. Neurogenic nasal inflammation was induced by capsaicin. Sedation potential and interaction with alcohol were assessed by i.v. and intracerebroventricular pentobarbital-induced sedation and alcohol-induced ataxia models. Results: Ovalbumin sensitization and challenge caused rhinitis pathology including inflammatory cell infiltration, IL-4, and protein leakage in the nasal lavage fluid (NLF) and presence of inflammatory cells in nasal epithelium. A 5-day treatment of antihistamines reduced these markers of inflammation. SUN-1334H, cetirizine and hydroxyzine caused comparable inhibition of NLF leukocytes, IL-4 and total protein concentrations. Fexofenadine and desloratadine showed moderate inhibition of NLF leukocytes and had no significant effect on IL-4 concentration. While fexofenadine had no effect on total protein concentration, the effect of desloratadine was comparable with the other antihistamines. In neurogenic nasal inflammation induced by capsaicin, SUN-1334H and fexofenadine caused better inhibition at lower and middle dose levels than the other antihistamines. In skin allergy models, SUN-1334H showed potent reduction of passive and active cutaneous anaphylactic reactions. In central nervous system side effects models, SUN-1334H, desloratadine and fexofenadine were devoid of any significant effects. Conclusions: The results are suggestive of a high anti-inflammatory to sedation index of SUN-1334H among leading antihistamines.