Skip to main content
OpenTrials
Completed

NCT Number: NCT03102177

Effect of Age, Weight and Sex on Levothyroxine Pharmacokinetics

This study was a prospective, single-center, open-label, non-randomized, pharmacokinetic study using stable isotope carbon-13 labeled levothyroxine

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Hypothyroidism Primary Endocrine System Diseases Hypothyroidism Thyroid Diseases

Age range

21 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Early Phase 1

About this study

Setting The study was conducted on the clinical research unit of an academic medical center.

Participants Adults of any age being treated with levothyroxine for hypothyroidism were studied.

Interventions A single dose of 13C- LT4 was administered to hypothyroid subjects taking levothyroxine replacement.

Main Outcomes and Measures Eighteen serial plasma samples were collected. One sample was obtained before the 13C- LT4 dose and the remainder over the 312-hour period post-dosing. 13C- LT4 concentration was quantified using validated liquid chromatography tandem mass spectrometry methods. Pharmacokinetic analysis was conducted using linear log trapezoidal non-compartmental analysis using Phoenix 6.4.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • age >21 years at the time of consent
  • euthyroidism while undergoing treatment with LT4
  • no other serious illness
  • ability to give written informed consent.

Exclusion criteria

  • baseline hematocrit lower than 28.0%
  • TSH greater than 4.5 mIU/L
  • kidney dysfunction
  • concomitant use of drugs that affect thyroidal axis interactions

Treatment and study plan

Administration of stable Isotope labeled levothyroxine

Drug

Administration of single dose of stable isotope carbon-13 labeled levothyroxine and measurement of blood levels of stable isotope-labeled levothyroxine

Other names: levothyroxine or synthroid

Primary outcomes

  1. CL/F

    Time frame: 120 hours

    oral clearance rate (defined as the ratio of dose administered to AUC0-∞)

  2. V/F

    Time frame: 120 hours

    apparent volume of distribution (estimated by CL/F/ λ)

  3. t-half

    Time frame: 120 hours

    the half-life of the terminal disposition phase (t-half) estimated by ln(2)/λ .

Secondary outcomes

  1. CL/F analysed by age groups

    Time frame: 120 hours

    CL/F will be compared in adults (age ≤60 years) versus elderly (age>60 years) using Wilcoxon signed-rank test using significance level of α = 0.05. Additionally, these PK parameters were regressed against age (as a continuous covariate).

    Sex (male or female), weight (as a continuous covariate), and body mass index (BMI) (as a continuous covariate) will be considered using a stepwise linear regression approach.

  2. V/F analysed by age groups

    Time frame: 120 hours

    V/F will be compared in adults (age ≤60 years) versus elderly (age>60 years) using Wilcoxon signed-rank test using significance level of α = 0.05. Additionally, these PK parameters were regressed against age (as a continuous covariate).

    Sex (male or female), weight (as a continuous covariate), and body mass index (BMI) (as a continuous covariate) will be considered using a stepwise linear regression approach.

  3. t-half by age groups

    Time frame: 120 hours

    t-half will be compared in adults (age ≤60 years) versus elderly (age>60 years) using Wilcoxon signed-rank test using significance level of α = 0.05. Additionally, these PK parameters were regressed against age (as a continuous covariate).

    Sex (male or female), weight (as a continuous covariate), and body mass index (BMI) (as a continuous covariate) will be considered using a stepwise linear regression approach.

Sponsors and collaborators

Lead sponsor

Georgetown University

Other

Registry information

Official study title

Hypothyroidism Treatment in Aging and Thyroid Cancer

Important dates

Study start
2011
Primary completion
2013
Study completion
2016
First posted
Apr 5, 2017
Registry last updated
Apr 6, 2017

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.