MOA of Valproic Acid?

[Old_Mil]

Pharmcards: blocks T-type Ca channels

Step Up: blocks thalamic K channels

First Aid: blocks T-type Na channels

Pharm Recall: prolongs the inactivation of Na channels


...best two out of four?

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[fakin' the funk]

Pharmcards: blocks T-type Ca channels

Step Up: blocks thalamic K channels

First Aid: blocks T-type Na channels

Pharm Recall: prolongs the inactivation of Na channels

Goodman & Gilman:
"At therapeutically relevant concentrations, valproate inhibits sustained repetitive firing induced by depolarization of mouse cortical or spinal cord neurons. The action is similar to that of both phenytoin and carbamazepine and appears to be mediated by a prolonged recovery of voltage-activated Na+ channels from inactivation. Valproic acid does not modify neuronal responses to iontophoretically applied GABA. In neurons isolated from the nodose ganglion, valproate also produces small reductions of the low-threshold (T) Ca2+ current at clinically relevant but slightly higher concentrations than those that limit sustained repetitive firing; this effect on T currents is similar to that of ethosuximide in thalamic neurons. Together, these actions of limiting sustained repetitive firing and reducing T currents may contribute to the effectiveness of valproic acid against partial and tonic-clonic seizures and absence seizures, respectively.

Another potential mechanism that may contribute to valproate's antiseizure actions involves metabolism of GABA..."

When in doubt, consult the experts.