Posted by Shawn. T. on August 24, 2005, at 20:59:07
In reply to Keppra pharmacological properties - Shawn T.?, posted by SLS on August 24, 2005, at 6:26:25
Keppra inhibits N-type calcium channels in a manner that is not related to their activation states (Lukyanetz et al., 2002; http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11879381). These channels have three general states: open, closed, and inactivated. The inactivated state transiently occurs after the open state, and an inactivated channel cannot open even under favorable voltages. Many drugs affect voltage-gated channels in a use-dependent manner, which means that they preferentially bind to the channel pore when it is inactivated. Keppra is not one of these drugs.
Lukyanetz et al. also suggested that only a certain subtype of N-type calcium channels may be affected by Keppra. They based this suggestion on their examination of Keppra's effects on CA1 pyramidal hippocampal neurons. Other researchers have found that kindling, an animal model for seizures, involves an increase in the expression of N-type calcium channels in CA1 and CA3 hippocampal neurons (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10625050). N-type calcium channels affect processes such as neurotransmitter release, synaptic plasticity, and gene expression. As a result, they may involved in the hyperexcitability of neurons and in some types of epilepsy. Keppra has been approved by the FDA for only one use: adjunctive therapy in the treatment of partial onset seizures in adults and children 4 years of age and older with epilepsy.
Shawn
poster:Shawn. T.
thread:545975
URL: http://www.dr-bob.org/babble/20050821/msgs/546308.html