Sodium valproate formulations

Divalproex sodium is comprised of sodium valproate and valproic acid. The delayed-release and extended-release formulations are converted in the small intestine into valproic add, which is the systemically absorbed form. It was developed as an antiepileptic drug, but also has efficacy for mood stabilization and migraine headaches. It is FDA-approved for the treatment of the manic phase of bipolar disorder. It is generally equal in efficacy to lithium and some other drugs for bipolar mania. It has particular utility in bipolar disorder patients with rapid cycling, mixed mood features, and substance abuse comorbidity. Although not FDA-approved for relapse prevention, studies support this use, and it is widely prescribed for maintenance therapy. Divalproex can be used as monotherapy or in combination with lithium or an antipsychotic drug.31... 

The formulations of phenytoin, carbamazepine and sodium valproate are compared in Table A17.3 overleaf. 

I Available in different formulations. Valproate semisodium (divalproex sodirnn in the USA) is a mixture of sodium valproate and valproic acid and is now hcensed in the UK for the treatment of acute mania. 

Increase dose by 10%-20% when converting from valproate, divalproex, or valproic acid to tiie extended-release (ER) formulation of divalproex sodium. 

Valproic acid. Although its exact mechanism of action remains uncertain, valproic acid (also valproate sodium, or valproate) may inhibit sodium and/or calcium channel function and perhaps thereby boost GABA inhibitory action as well as reduce glutamate excitatory action (Fig. 7—23). A unique and patented pharmaceutical formulation of valproic acid, called Depakote, reduces gastrointestinal side effects. 

Valproic acid is available as sodium, magnesium, and calcium salts, as the free acid, and as a coordination compound, valproate semisodium (divalproex sodium), which comprises the sodium salt of valproic acid and free valproic acid in a 1 1 molar ratio. AH share the same active principle (valproic acid) and have virtually identical tolerability, although the formulation influences the incidence of gastrointestinal adverse effects. Valpromide (rINN) is a prodrug of valproate, to which it is converted with a half-hfe of less than 1 hour. Valnoctamide (rINN) is an isomer of valpromide. 

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