Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2019 Publisher: G.L. Pharma GmbH, Schlossplatz 1, 8502 Lannach, Austria
Pharmacotherapeutic group: antiepileptics, fatty acid derivates
ATC code: N03AG01
The most likely mode of action for valproate is potentiation of the inhibitory action of gamma amino butyric acid (GABA) through an action on the further synthesis or further metabolism of GABA.
In certain in-vitro studies it was reported that sodium valproate could stimulate HIV replication but studies on peripheral blood mononuclear cells from HIV-infected subjects show that sodium valproate does not have a mitogen-like effect on inducing HIV replication. Indeed the effect of sodium valproate on HIV replication ex-vivo is highly variable, modest in quantity, appears to be unrelated to the dose and has not been documented in man.
The half-life of valproate is usually reported to be within the range of 8-20 hours. It is usually shorter in children.
In patients with severe renal insufficiency it may be necessary to alter dosage in accordance with free plasma valproic acid levels.
The reported effective therapeutic range for plasma valproic acid levels is 40-100mg/litre (278-694 micromol/litre). This reported range may depend on time of sampling and presence of co-medication.
The percentage of free (unbound) drug is usually between 6% and 15% of total plasma levels. An increased incidence of adverse effects may occur with plasma levels above the effective therapeutic range.
The pharmacological (or therapeutic) effects of Convulex may not be clearly correlated with the total or free (unbound) plasma valproic acid levels.
There are no pre-clinical data of relevance to the prescriber which are additional to those already stated in other sections of the SmPC.
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