Retrospective Study of Patients Switched from Tablet Formulations to a Gel Cap Formulation of Levothyroxine: Results of the CONTROL Switch Study.

Abstract

IntroductionMedication changes involving levothyroxine—either dose titrations or switching formulations—occur frequently in patients with erratic thyroid-stimulating hormone (TSH) levels and persistent hypothyroid symptoms. We investigated whether switching patients from levothyroxine tablets to a gel cap formulation of levothyroxine might reduce dose adjustments and improve tolerability and efficacy outcomes.ObjectivesPrimary study objectives included quantifying the percentage of patients achieving TSH levels within a pre-specified range, median dose changes experienced, and the percentage of patients with improved hypothyroid symptom control after switching from levothyroxine tablets to levothyroxine gel caps.MethodsA retrospective medical chart review was conducted among 99 randomly selected hypothyroid patients who were switched from a tablet to a gel cap formulation of levothyroxine. Patients were required to have been on levothyroxine monotherapy for ≥1 year prior to the medication switch. Data was collected for 6 months pre-switch and up to 6 months post-switch.ResultsOf the 99 patients studied, the majority (51.5%) experienced no documented change in TSH status after the switch (P < 0.0001). However, there was a decrease in the mean number of dose changes experienced (1.61 ± 0.96 vs. 0.73 ± 0.96; P < 0.0001). Improved hypothyroid symptom control was reported among 61.6% of patients (61 of 99; P < 0.0001).ConclusionThe results of CONTROL Switch support a strategy of switching patients who may experience tolerability or efficacy problems with standard levothyroxine tablets to the levothyroxine gel cap formulation.