Key Medications to Monitor
Other common outpatient medications that should be closely monitored in patients experiencing rapid weight loss, by any method, range from anticoagulants, anticonvulsants, and antituberculosis drugs to antibiotics and antifungals, the authors note.
Of note, medications with a narrow therapeutic index include phenytoin, warfarin, lithium carbonate, digoxin theophylline, tacrolimus, valproic acid, carbamazepine, and cyclosporine.
The failure to make necessary dose adjustments “is seen more often since the newer antiobesity drugs reduce a great amount of weight within months, almost as rapidly as bariatric surgery,” Dr. Karakus said.
“It is very important for physicians to be aware of the weight-based medications and narrow therapeutic index medications since their doses should be adjusted carefully, especially during weight loss,” he added.
Furthermore, “the patient should also know that weight reduction medication may cause adverse effects like nausea, vomiting and also may affect metabolism of other medications such that some medication doses should be adjusted regularly.”
In the editorial published with the study, Tyrone A. Johnson, MD, of the Department of Medicine, University of California, San Francisco, and colleagues note that the need for close monitoring is particularly important with older patients, who, in addition to having a higher likelihood of comorbidities, commonly have polypharmacy that could increase the potential for adverse effects.
Another key area concern is the emergence of direct-to-consumer avenues for GLP-1/GIP agonists for the many who either cannot afford or do not have access to the drugs, providing further opportunities for treatment without appropriate clinical oversight, they add.
Overall, the case “highlights the potential dangers underlying under-supervised prescribing of GLP-1/GIP receptor agonists and affirms the need for strong partnerships between patients and their clinicians during their use,” they wrote.
“These medications are best used in collaboration with continuity care teams, in context of a patient’s entire health, and in comprehensive risk-benefit assessment throughout the entire duration of treatment.”
A Caveat: Subclinical Levothyroxine Dosing
Commenting on the study, Matthew Ettleson, MD, a clinical instructor of medicine in the Section of Endocrinology, Diabetes, & Metabolism, University of Chicago, noted the important caveat that patients with hypothyroidism are commonly on subclinical doses, with varying dose adjustment needs.
“The patient in the case was clearly on a replacement level dose. However, many patients are on low doses of levothyroxine (75 µg or lower) for subclinical hypothyroidism, and, in general, I think the risks are lower with patients with subclinical hypothyroidism on lower doses of levothyroxine,” he told this news organization.
Because of that, “frequent TSH monitoring may be excessive in this population,” he said. “I would hesitate to empirically lower the dose with weight loss, unless it was clear that the patient was unlikely to follow up.
“Checking TSH at a more frequent interval and adjusting the dose accordingly should be adequate to prevent situations like this case.”
Dr. Karakus, Dr. Ettleson, and the editorial authors had no relevant disclosures to report.
A version of this article appeared on Medscape.com.