Bioequivalence with shorter versus longer waits before coffee/breakfast
The Thyquidity coffee study was a single-center open-label, randomized, crossover study of 40 healthy adults randomized after a 10-hour overnight fast to 600 µg Thyquidity with water under fasting conditions or to the same dose given 5 minutes prior to drinking an 8-ounce cup of American coffee without milk or sweeteners. After a 40-day washout period, the same participants received the other treatment.
Mean serum thyroxine (T4) concentrations over 48 hours were nearly identical, demonstrating comparable bioavailability. Pharmacokinetics parameters, including area under the curve (AUC) and Cmax, were also comparable for both groups. The geometric least square mean ratios for baseline-adjusted LT4 were 96.0% for Cmax and 94% for AUC. And the corresponding 90% confidence intervals fell within the 80%-125% FDA acceptance range for absence of a food effect on bioavailability, said Dr. Washington when presenting the findings.
There was one adverse event, a decrease in blood glucose level, which was deemed to be mild and unrelated to study treatment. No deaths, serious adverse events, or discontinuations due to adverse events were reported. There were no significant changes in vital signs or on ECG.
In the second Thyquidity study of 38 healthy adults, after a 10-hour fast, the same doses were given 10 or 30 minutes prior to the consumption of a 950-calorie standardized high-fat breakfast.
Again, over 48 hours, mean serum T4 levels were comparable between the two groups. The geometric least squares mean ratios for both AUC and Cmax for baseline-adjusted LT4 were 88.7% and 85.1%, respectively. Again, the corresponding 90% confidence intervals fell within the FDA’s noninterference definition, again demonstrating lack of a food effect on bioavailability, Dr. Washington noted.
Four adverse events were reported in three participants, with three deemed to be possibly related to the medication. All were isolated lab abnormalities without clinical symptoms and deemed to be mild. Three were normal on repeat testing.
There were no deaths or serious adverse events or study discontinuations for adverse events and no significant findings for vital signs or on ECG.
Similar findings for Tirosint-SOL but longer-term studies needed
The recently published Tirosint-SOL study included 36 healthy volunteers randomized to single 600-µg doses of the LT4 oral solution after a 10-hour fast, either 15 or 30 minutes before eating a standardized high-fat, high-calorie meal. Mean serum total thyroxine concentration profiles were similar for both the 15- and 30-minute waits, with similar AUCs.
Geometric mean ratios for AUCs at 48 and 72 hours were 90% and 92%, respectively, and the 90% confidence intervals fell within the 80%-125% FDA boundaries, suggesting similar exposures whether taken 15 or 30 minutes before a meal.
Senior author Francesco S. Celi, MD, chair of the division of endocrinology, diabetes, and metabolism at Virginia Commonwealth University, Richmond, told this news organization: “There is an interest in providing more opportunities for patients and improving adherence to the medication. ... Whatever makes life a bit easier for patients and results in a more predictable response to treatment means down the road there will be fewer visits to the doctor to make adjustments.”
However, he said that in addition to the cost and reimbursement issue, all of these studies have been short term and not conducted in real-life settings.
“Another question is: What happens if the patient goes on low-dose LT4? The studies were conducted on much higher pharmacologic doses. But at least from a safety standpoint, there’s no specific concern.”
Dr. Washington is an employee of Vertice Pharma. Dr. Celi has received unrestricted research grants and worked as a consultant for IBSA. Dr. Gigliotti has reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.