As cardiopulmonologist Mark Pamer, DO, goes about his day at his South Florida practice, one adage from medical school that sticks in his mind is: “All that wheezes is not asthma.”
“[As doctors], we probably all heard that. Did we understand it? You know, probably not,” said Dr. Pamer. “We understood it later on in residency or fellowship or in life.”
This adage proved itself during Dr. Pamer’s treatment of a puzzling patient case involving a 59-year-old man who came into his practice with all the classic signs of asthma. It was worse in the winter and around animals, and included nasal congestion. The patient also had history of gastroesophageal reflux disease (GERD) also known as acid reflux, hypertension, irritable bowel syndrome and tremors.
The patient was on multiple medications, including fluticasone/ salmeterol (Advair) for asthma, dexlansoprazole (Dexilant) for GERD and primidone (Mysoline) for tremors, in addition to a rescue inhaler.
The patient came to Dr. Pamer complaining of worsening asthma symptoms, so the dose of Advair was increased. A month later, the asthma symptoms had not changed. Pulmonary function tests and chest x-rays simply did not point to asthma.
Dr. Pamer stopped the Advair and had the patient evaluated for asthma-mimicking states, which can include acid reflux. These tests showed the patient’s reflux was not being controlled by the Dexilant, which is metabolized by the highly variable CYP2C19 enzyme pathway.
Fortunately, Dr. Pamer knew the value of the YouScript Personalized Prescribing System in figuring out tough cases. Genotyping and YouScript analysis revealed the patient to be a CYP2C19 rapid metabolizer, which was predicted to decrease the blood levels of Dexilant.
Primidone, being an inducer of both CYP2C19 and CYP3A4, was likely decreasing Dexilant blood levels even more. Together, these factors resulted in a clinically significant increase in Dexilant metabolism and a decrease indrug effectiveness.
This analysis, in combination with a 24-hour pH probe on the patient, revealed his asthma symptoms were actually a result of acid reflux. The reflux, in turn, was the result of both the patient’s genetics and a drug-drug interaction that was drastically reducing the blood levels of Dexilant.
“I wouldn’t have learned any of this from talking to him,” Dr. Pamer explained. “It just seemed that he had horrible asthma.”
After Dr. Pamer consulted with the patient’s neurologist, the 59-year-old was titrated off primidone. Additionally, his Dexilant was replaced with rabeprazole (Aciphex), which is not as dependent on the CYP2C19 pathway for drug metabolism. The patient’s “asthma” was controlled, and his cough went away.
“I’ll tell you that your knowledge base improves exponentially once you start to use this test,” Dr. Pamer said of YouScript.