The psychiatric-mental health nurse practitioner is treating a 26-year-old woman diagnosed with bipolar I disorder who has exhibited a partial response to Lamictal 200 mg PO BID. The PMHNP wants to augment the Lamictal with valproate (Depakote). To do so, how must she change the dose of Lamictal?

Choice A reason: Lamictal metabolism is affected by valproate; failing to adjust the dose increases the risk of toxicity. Choice B reason: Doubling the dose would increase the risk of serious adverse effects, including life-threatening rash. Choice C reason: Valproate inhibits Lamictal metabolism, so the dose of Lamictal must be reduced to avoid toxic accumulation. Choice D reason: The two medications are not contraindicated; they can be used together with proper dose adjustment.