Strengths:

Established efficacy in acute mania

• The acute and prophylactic response with valproate was most notable in patients with mania and mixed states. [ICG Guidelines]
• Valproate should be considered as add-on therapy in breakthrough mania because it has proven efficacy in mania. [ICG Guidelines]

Weaknesses:

Evidence supporting valproate as bipolar maintenance therapy is limited and inconsistent

• While unlikely to provoke a manic switch, lithium, valproate, and carbamazepine have inadequate evidence for efficacy as acute antidepressants. [BAP Guidelines]

Side effects including somnolence, weight gain, and endocrine changes

• Valproate, lithium, and several antipsychotics all cause significant weight gain in patients with long-term treatment. Weight gain is associated with other adverse metabolic effects (e.g. carbohydrate intolerance/type II diabetes and hyperlipidemia) and hypertension. [WFSBP Guidelines]