Topiramate (Topamax) is used for various reasons outlined below. We wanted to cover some of the most common topiramate clinical pearls and how these might affect our patients. Let’s start with a brief case scenario.
Mrs. KC, 45 years old came into the clinic for her medication review today. She says to you that managing her migraine is a concern. She is currently taking nortriptyline 25 mg once daily at night, topiramate 50 mg in the morning, and topiramate 100 mg at night for migraine prophylaxis with partial response. She is also taking rizatriptan 10 mg orally when required, placing one wafer on the tongue for an acute migraine attack. The attending physician is considering increasing topiramate further. What should we look out for with this medication?
Let’s start with a general overview. The exact mechanism of action for topiramate is unknown. FDA-approved indications for topiramate include tonic-clonic seizure, partial seizure and prevention of migraine. It is also used off-label in alcoholism, eating disorder, essential tremor, and obesity (side effects of topiramate include loss of appetite, taste disturbance, weight loss).
What are some common adverse effects of topiramate? By far, one of the most commonly reported issues with topiramate is cognitive impairment. Some patients will have trouble remembering things or just feel like they cannot think clearly or quickly to do their daily functions. As the dose escalates, it is important to watch for this. Remembering the brand name of this medication helps me remember this adverse effect (Topamax, “Dopamax”). In the case above, we probably aren’t too concerned about dementia, but in our elderly patients who may be at higher risk of dementia, it is critical to recognize and address that a patient is taking this medication prior to considering a new medical diagnosis.
Less common, but importantly, metabolic acidosis has been reported in patients taking topiramate, especially if they have pre-existing conditions such as renal disease and severe respiratory disorders. Patients with metabolic acidosis usually have ↓PH, ↓HCO3 and ↓PCO2. Patients may complain of nausea, vomiting, lethargy, and hyperpnea (deep breathing).
Kidney stones are weight loss are also adverse effects to keep an eye out for when a patient is taking long-term therapy.
What are some other counseling points while on long term topiramate therapy?
Encourage the patient to keep hydrated during therapy as topiramate may reduce sweating and cause hyperthermia. Risk increased if used concurrently with drugs with anticholinergics properties. The risk of hyperthermia may also increase with situations where patients are in warmer environments than they are used to. Adequate hydration may also help to reduce the risk of renal stones.
What other topiramate clinical pearls do you pay attention to?
The article was written by Jiamin Liau in collaboration with Eric Christianson, PharmD, BCGP, BCPS
Looking for an interesting drug interaction on topiramate? Check this one out!