药理学第二章课件.pptVIP

抗癫药及抗惊厥药 Antiepileptic and Anticonvulsant  Antiepileptic and anticonvulsant drugs suppress the abnormal high-frequency discharge of neurons. Primary drugs mainly include phenytoin, carbamazepine, valproate and ethosuximide. Secondary drugs include diazepam and phenobarbital which are used intravenously in the treatment of status epilepticus. Anti - epileptic drugs are thought to act principally, by two mechanisms: ① reducing electrical excitability of neuron membranes, possibly through use - dependent block of Na+ channels, and ② enhancing GABA -mediated synaptic inhibition, which may result from an enhanced postsynaptic action of GABA, or inhibition of GAGA transaminase or GABA uptake, or direct stimulation of GABA receptors. A few drugs also appear to act by other mechanisms, namely, through inhibition of T-type Ca2+ channels or of glutamate receptors. Primary anticonvulsants include diazepam, phenobarbital and magnesium sulfate. The latter also exerts muscle relaxation by blocking Ca2+ influx in presynaptic nerve terminals. Neurodegenerative diseases, such as Parkinsonism, Huntingtons disease and Alzheimers disease, are all associated with progressive loss of neurons and their functions. If properly managed, drugs do not cure but greatly improve the quality of life in this progressive disease. The strategy of treatment of Parkinsons disease is aimed at restoring dopaminergic/cholinergic balance by one of a number of ways as follows: 1. Reducing cholinergic activity with antimuscarinic (anticholinergic) drugs; this approach is most effective in the acute treatment of rigidity (including iatrogenic, caused by dopamine receptor antagonists); 2. Enhancing dopaminergic activity with dopaminergic drugs by prolonging the action of dopamine through selective inhibition of its metabolism ( selegiline ), activating dopamine receptors ( bromocriptine, lysuride, apomorphine), and modulating the release of dopamine from stores and the reuptake of dopamine (amantadi