Ranolazine is an antianginal agent that exerts its therapeutic effect via neuronal sodium channels. Ranolazine is approved for the treatment of chronic angina when symptoms persist despite the use of first-line therapies such as nitrates, beta blockers, and calcium channel blockers.
An 81-year-old Caucasian woman was admitted to the hospital with complaints of substernal chest pain. Her medication regimen prior to admission was aspirin 81 mg daily, metoprolol tartrate 12.5 mg twice daily, clopidogrel 75 mg daily, rosuvastatin 5 mg daily, nitroglycerine SL 0.4 mg as needed, citalopram 40 mg daily, omeprazole 40 mg twice daily, and allopurinol 300 mg daily. At baseline, the patient had some early signs of dementia, including word-finding difficulties and short episodes of agitation associated with confusion.
The patient’s troponin T level was 1.3 ng/mL (reference level, 0.0 ng/mL) and a CK-MB level of 36 ng/mL (reference range, 0.0-6.6 ng/mL) but no evidence of EKG changes. Her liver function tests were within normal limits, and her serum creatinine was elevated at 1.6 mg/dL (reference range, 0.5-1.2 mg/dL) with an estimated creatinine clearance of 20 mL/min. The patient received a cardiac catheterization but was deemed not a candidate for surgical intervention, so optimization of her antianginal medications was initiated. Ranolazine was initiated at 500 mg twice daily because up-titration of her metoprolol was not feasible due to heart rate and blood pressure restrictions.
On hospital day 3, her ranolazine dosage was increased to 1,000 mg twice daily, and isosorbide dinitrate 10 mg 3 times daily was initiated because the patient was continuing to experience intermittent chest pain. Four days after ranolazine initiation, the patient exhibited mild confusion and word-finding difficulties. On this day, her serum creatinine had risen to 1.9 mg/dL; dehydration and exposure to contrast media during her catheterization were thought to have contributed to her worsening renal function. Day 5 brought increased central nervous system symptoms including dysarthria, dysmetria, increased word-finding difficulties, and difficulty with ambulation due to intense tremors and hallucinations. On day 5, ranolazine was discontinued and within 2 days her neurologic signs and symptoms markedly improved. Four weeks after discharge, the patient did not display dysarthria, dysmetria, tremors, or hallucinations.
The authors theorize that because ranolazine has a piperazine ring in its chemical structure, it may be responsible for the neurologic adverse effects exhibited by the patient. It should be noted that a piperazine ring is also a part of many psychotropic drugs, including antidepressants, antipsychotics, and illicit hallucinogens. Ranolazine is also structurally similar to lidocaine and was thought to have therapeutic potential for the treatment of pain syndromes during the drug development process. Animal studies utilizing high doses of ranolazine observed neurologic adverse effects of bradykinesia, motor sluggishness, muscle fasciculations, twitching, and convulsions. The pharmacokinetics of ranolazine are considerably affected by age and hepatic and renal impairment.
The authors made the following recommendation, “Patients with underlying neurologic disease, even when mild, should be monitored carefully when initiating or increasing the dose of ranolazine. Elderly patients with age-related decreases in renal and hepatic function are at increased risk of elevated ranolazine serum concentrations and, thus, adverse effects. We recommend a maximum ranolazine dosage of 500 mg twice daily for patients who are older than 80 years or who have a creatinine clearance of less than 30 mL/min.”
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