The most appropriate management is to discontinue metoclopramide and begin promethazine. Replacing the metoclopramide with a scheduled antiemetic is the safest and most cost-effective next step in management. The initial treatment of diabetic gastroparesis should include a dietary management plan consisting of frequent small-volume meals that are low in fat and soluble fiber. Equally important is tight glycemic control because acute hyperglycemia can impair gastric emptying, often resulting in nausea, vomiting, and abdominal pain. When these initial treatment modalities are ineffective, the use of the prokinetic agent metoclopramide is indicated. Metoclopramide is the only drug approved by the FDA for the treatment of gastroparesis. Metoclopramide crosses the blood-brain barrier and potentially causes side effects such as hyperprolactinemia, galactorrhea, and a variety of neurologic symptoms such as tardive dyskinesia. The risks of neurologic side effects are increased with chronic therapy (greater than 3 months) and with use in the elderly and in women. Drug-induced movement disorders are the most concerning neurologic symptoms. Patients taking metoclopramide should receive counseling about these potential adverse effects and should notify the prescriber immediately if these symptoms develop. Symptoms are likely to progress in severity and may become permanent with continued therapy. Although metoclopramide was effective at relieving this patient's gastroparesis symptoms, her neurologic symptoms mandate its prompt discontinuation. Simply decreasing the dose of metoclopramide is unlikely to resolve the neurologic symptoms. Although antiemetic therapy will not improve gastric emptying, it can be very effective for symptoms of nausea and vomiting.

Gastric electrical stimulation with a gastric pacemaker may be considered for compassionate treatment in patients with refractory symptoms of nausea and vomiting in whom all other forms of more conservative therapy have failed.

Given the lack of superiority to placebo in randomized clinical trials, intrapyloric injection of botulinum toxin cannot be recommended for patients with gastroparesis.