Seizures histamine effects

Drugs that act on the H3 receptor are being developed for the treatment of obesity, sleep disturbances, epilepsy and cognitive disorders. The ability of histamine to promote arousal, suppress appetite, elevate seizure threshold and stimulate cognitive processes implies that compounds able to enhance the release of neuronal histamine should mimic these effects. Several H3 antagonists currently in development demonstrate such activity and show promise as effective and novel therapeutic agents [40, 84-86]. Because H3 agonists suppress the release of... 

Deficiency of this coenzyme can lead to many manifestations. Clinical signs include retarded growth, acrodynia, alopecia, skeletal changes and anemia, while changes in neurotransmitters, such as dopamine, serotonin, norepinephrine (noradrenaline), tryptamine, tyramine, histamine, y-aminobutyric acid, and taurine, affect the brain function and can lead to seizures and convulsions. An overdose of vitamin Bg leads to neuronal damage and sensory and motor effects [417],... 

Neurological Extrapyramidal side effects, sedation, seizures Dopamine 2, histamine Examine for Parkinsonism, akath-isia, and abnormal involuntary movements at each visit Baseline electroencephalogram if treated with clozapine. 

Imipramine Mixed and variable blockade of NET and SERT Like SNRIs plus significant blockade of autonomic nervous system and histamine receptors Major depression not responsive to other drugs chronic pain disorders incontinence obsessive-compulsive disorder (clomipramine) Long half-lives CYP substrates active metabolites Toxicity Anticholinergic, G.-blocking effects, sedation, weight gain, arrhythmias, and seizures in overdose Interactions CYP inducers and inhibitors... 

There is evidence that the central histaminergic neurons play an important role in inhibiting convulsions in the immature brain, where the GABA system is less effective than in the adult brain. Histamine acts via an Hi receptor and other Hi receptor antagonists can cause seizures. The authors proposed that ketotifen induces infantile spasms by antagonizing Hi receptors. 

Phenothiazines primariiy biock postsynaptic neurotransmission by binding to dopamine (Di and D2), muscarinic, histamine Hj, and serotonergic 5-HT2 receptors. Phenothiazines also possess peripheral a-adrenergic receptor blockade and quinidine-like cardiac effects. Phenothiazines may also lower the seizure threshold. 

Bupropion (100 mg p.o. b.i.d.) is indicated in the treatment of depression. It is reserved for patients who cannot tolerate or have not responded to other medications. Bupropion does not alter the uptake of serotonin, has an equivocal effect on the uptake of norepinephrine, but blocks the uptake of dopamine. Bupropion has no affinity for alpha-1 and alpha-2-adrenergic receptors, H,-histamine receptors, muscarinic cholinergic receptors, or D2-dopaminergic receptors. It does not cause sedation or orthostatic hypotension. However, because it is structurally related to amphetamine, it may cause insomnia, agitation, and anxiety shortly after initiation of therapy. Bupropion lowers the seizure threshold and hence is contraindicated in patients with a history of seizure disorder (see also Tables 5 through 7). 

Mesoridazine, a metabolite of thioridazine, is thought to exert its antipsychotic effects by postsynaptic blockade of CNS dopamine receptors, thereby inhibiting dopamine-mediated effects. Mesoridazine has many other central and peripheral affects it produces both alpha and ganglionic blockade and counteracts histamine- and serotonin-mediated activities. Mesoridazine and thioridazine cause fewer movement disorders (see Phenotheazine Derivatives). Mesoridazine is metabolized to inactive metabolites, which are excreted by the kidneys. Overdosage of mesoridazine causes CNS depression characterized by deep, unarousable sleep, convulsive seizures, and cardiac arrhythmias (see also Table 2). 

The pharmacological properties of hydroxyzine are quite similar to those of chlorpromazine. It has antihistamine and anti-acetylcholine actions as have, indeed, most of the derivatives listed. Like chlorpromazine, hydroxyzine is anticonvulsive, it potentiates the action of hypnotics, it produces hypothermia and hypotension, it depresses the reticular system and it has some anti-adrenaline action. Extrapyramidal side effects do not, apparently, occur, perhaps because of the drug s rather powerful anti-acetylcholine action which probably also explains such side effects as dryness of the mouth and the occasional occurrence of central excitation. Epileptiform seizures have also been seen during hydroxyzine therapy. The fact that anti-acetylcholine and antihistamine activity is found with many of the diphenylmethane derivatives, whether depressant or excitatory, suggests that the tranquillizing effect of hydroxyzine cannot be due to its antagonizing the action of acetylcholine or histamine. 

The main product of the Hofmann elimination of atracurium is laudanosine, an alpha-adrenoreceptor blocking agent which causes hypotension. Moreover, laudanosine crosses the blood-brain barrier (in contrast to the parent compound) and may cause excitement and seizure activity which leads to an increase in anaesthetic requirement by 30%. Accumulation and corresponding problems with laudanosine arise only in infants and with prolonged application in ICUs. ° Laudanosine-caused hypotension is enhanced by histamine released from tissue stores as a side effect of atracurium. 

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