The drug levothyroxine (Synthroid, Levoxyl, others) has long been the treatment for sluggish thyroids or hypothyroidism. The pill needs time to be absorbed properly, so patients are often instructed to take it daily a half hour to an hour before breakfast. But that can make the regimen inconvenient for some, and compliance declines.
Now, a new study suggests that weekly doses appear to work as well. Indian researchers presented the findings at the 2016 annual meeting of the American Association of Clinical Endocrinologists in Orlando. "Once weekly L-thyroxine replacement was well tolerated and there was no indication of acute toxicity or hypothyroidism symptoms compared with daily therapy," according to researchers Satish Wasoori, MD, and Manoj Naik, MD, of Park Hospital in Guragaon, India. The new study echoes some findings from previous research.
U.S. endocrinologists who reviewed the findings say, in general, they still prefer daily dosing.
In the new research, the doctors evaluated 40 women, ages 25 to 55, who had been diagnosed with hypothyroidism for at least five years and were on a daily dose of levothyroxine. They assigned them to two groups. One group had thyroid-stimulating hormone (TSH) levels viewed as in the normal range at the start; the other group had levels that were above the normal range. Higher TSH levels indicate a failing thyroid, according to the American Thyroid Association.
Both groups of women took a weekly dose of levothyroxine seven times their daily dose, following the regimen for six months. Those in group 1, with TSH levels closer to ideal to start with, all maintained normal thyroid functioning by 12 weeks into the study and maintained it at the six-month mark. In group 2, 16 of 20 had normal functioning at 12 weeks and 18 did by the six-month mark. Two did not achieve normal thyroid function, probably due to underlying diabetes and obesity, the researchers say.
The researchers say the weekly regimen is effective and safe, ''making it a possible alternative to customary daily therapy." They also concluded that the once-a-week regimen ''can be considered as first-line therapy in working young and middle-aged women facing impaired absorption due to early breakfast." They would need to take the weekly dose on an empty stomach, but could skip that waiting period the other six days.
Not everyone is on board with that idea. "There is no question that daily therapy is preferable to weekly therapy," says Jacqueline Jonklaas, MD, associate professor of endocrinology at Georgetown University Medical Center, Washington, D.C. She reviewed the new data.
Why? "The 'half life' of thyroid hormone (how long it stays in your system) means that if you give it daily there are minimal peaks and troughs (ups and downs) in its blood level," she says. "However, if you give a larger dose on a weekly basis there are big peaks and troughs. This means that a patient may have symptoms of too much thyroid hormone right after the dose is given and symptoms of too little right before the next dose is due to be given. This is not at all ideal. The high levels could potentially be associated with risks such as a fast or irregular heart beat."
In her view, "the only patient who might be considered for weekly therapy is someone who could not be kept with normal thyroid levels on daily therapy." That's usually due to failing to take the medicine daily, she says. "Therefore, weekly therapy would only be a compromise when normal levels just cannot be achieved with daily therapy."
The suggestion to consider weekly dosing a ''first-line'' therapy for some is a bit aggressive, agrees Daniel Nadeau, MD, the Dr. Kris V. Iyer endowed chair in diabetes care and program director of the Mary & Dick Allen Diabetes Center at Hoag Hospital, Newport Beach, Ca. He reviewed the findings.
Instead, he says, "I think once weekly is an option when there is an individual who for whatever reason can't use daily dosing." If someone is on a weekly dose, he says, he would recommend waiting a full hour before eating.
Multiple studies dating back several years have looked at weekly dosing, says Matthew Freeby, MD, director of the UCLA Diabetes Center of Santa Monica and assistant clinical professor of medicine at the David Geffen UCLA School of Medicine. While research in general has found patients do fine, he says he would not recommend it for those with heart disease.
Remembering the daily dose is easier, Dr. Nadeau says, if patients keep the medication at their bedside. "As soon as they wake up, take it," he says. Then, they can go about their morning routine for a few minutes before eating breakfast, while the medication is absorbed, he says.
Most do not have an issue remembering the daily dose, says Dr. Jonklaas says, adding that medicine can be taken morning or evening. "Patients can put their thyroid hormone on their night stand, next to their tooth brush, use a weekly pill container, set an i-phone alarm and so on," she says. "I think working on finding a schedule that someone can keep to would be far preferable to pursuing weekly therapy. I also worry that this is not ideal for women of child-bearing potential. I do not think the up and downs in thyroid hormone would be optimum during pregnancy."
If the problem is an absorption issue, she says, that can be remedied by using liquid thyroid medicine or treated whatever is causing the poor absorption.
Current guidelines issued in 2014 by the American Thyroid Association say weekly dosing can be considered if a patient has compliance issues.
1. Synthyroid dosing: https://www.synthroid.com/what-is-synthroid/dosage
2. Abstract book…page 294, abstract 1182… attached one sheet as IMG screen shot. http://am.aace.com/sites/all/files/AbstractBook-2016_ALL.pdf