Combination therapy with levothyroxine and liothyronine triiodotyronine or T3 has been suggested as an alternative, however, the present evidence from clinical trials does not show any benefit for combination therapy compared with monotherapy with levothyroxine 9 - Recent evidence has suggested that the dose of levothyroxine replacement is dependent on sex and body mass, but not age as it was previously thought 1 , 14 , Many factors affect the absorption of levothyroxine; Medications such as calcium and iron compounds, aluminium hydroxide, selenium, magnesium, zinc, cholestyramine, sucralfate, raloxifene, proton pump inhibitors, and H2 blockers as well as caffeine, soybean, and fibers can impair the absorption of ingested levothyroxine 1 , 7 , 16 , Phenytoin, carbamazepine, phenobarbital, and rifampicin can increase the clearance of levothyroxine 7.
Thus, it should be taken on an empty stomach without other medications, supplements, or food for 1 hour or in a similar fashion 4 hours after the last meal. A fasting regimen of administration helps to ensure that the TSH remains within a narrow target range 1 , 7. The usual time schedule for taking levothyroxine tablets in patients with hypothyroidism is done every morning, before breakfast.
However, some patients have difficulties in taking their medication at early morning due to gastrointestinal disturbance, forgetting the drug and pregnancy. Thus, several studies have been performed to evaluate the efficacy of the evening dose of levothyroxine 18 - However, the literature data are inconsistent and contradictory. It has been demonstrated in the studies of Bartalena et al.
On the other hand, Bach-Huynh et al. A more recent study by Rajput et al. The aim of this study was to investigate the effect of changing the levothyroxine administration time from before breakfast to before dinner on serum TSH land T4 levels in patients with primary hypothyroidism.
This administration schedule was opted in order to evade the possibility of taking levothyroxine tablets on a full stomach as a result of short interval between dinner time and bedtime according to the general trait in the region here, the study was conducted and to reduce the possibility of forgetting the bedtime dose. Trial design: The present study was a prospective, randomized, double-blind, cross-over placebo controlled study.
Informed written consent was obtained from all the patients. Patients with a history of gastrointestinal disorders, chronic pulmonary disorders, chronic cardiovascular disease, renal failure, diabetes, concomitant use of medications that interfere with absorption or metabolism of levothyroxine such as cholestyramine and antibiotics and soon , and pregnant women were excluded from the study.
To ensure the normal levels of TSH and T4, all patients underwent laboratory tests before the commencement of the study. In cases of TSH and T4 values above or below the normal range, the patients were subjected to levothyroxine dose adjustment and were followed-up until the normal serum levels of TSH and T4 were achieved. Trial procedure: The patients were randomly divided into two groups following a simple randomization procedure using a computer generated list of random numbers.
Patients of both groups received one batch of levothyroxine and one batch of placebo and were recommended to take the tablets with a hour interval one before breakfast and one before dinner with the predetermined dosage.
The levothyroxine tablets and the placebo tablets prepared by the same manufacturer Iran Hormone co, Tehran, Iran were identical in shape, color and size and were packed in similar blisters. The blisters were coded with label of different colors yellow in the case of placebo and green in the case of levothyroxine. Neither the patients nor the physicians were aware of the randomization codes until the end of the study.
The study consisted of two 60 day courses. During the first course, group A received the levothyroxine tablets in the morning, 30 minutes before breakfast, and the placebo tablet 1 hour before dinner; whereas, group B received the levothyroxine and placebo tablets in reverse order. During the second course, the levothyroxine and placebo administration times were switched within each group.
The primary outcomes wherein the serum levels of T4 and TSH were measured at the end of the first and second course on the 60 th and th day of the study using ELISA. The serum concentration values of 0. The paired- sample t-test was used to compare the data and the value of p-less than 0.
The total number of 54 patients between 18 and 67 years were recruited in the study. Two patients one in each arm discontinued the study due to fear that changing the therapeutic regimen their disease might deteriorate and two patients one in each arm were lost to follow-up, while the 50 remaining patients were analyzed 25 patients in each group.
The full participant flow diagram is depicted in figure 1. The average administered dose of levothyroxine for the whole study population was 0. The most common symptoms among these patients were: dyspnea, excessive weight gain and hypersomnia. In both groups, within group differences in the serum TSH and T4 levels as a result of changing the administration time were similar. Since the results in both crossed over groups were the same, the two groups could be regarded as one.
To investigate the effect of age on dependent variables, the data were evaluated regarding different age groups less than 40 years and more than 40 years. The current therapeutic procedure for hypothyroidism is mainly focused on hormone replacement therapy by sodium levothyroxine. The patients are usually advised to take the medication in the morning minutes before breakfast.
However, many patients with hypothyroidism find it inconvenient to take the drug on an empty stomach in the morning because of their lifestyle, and intake of multiple other drugs which they are regularly consuming and often request their treating physicians to prescribe the drug at some alternate time of the day. The results of the study conducted by Bolk et al. They found it to be safe and well tolerated. They found out that changing the timings of thyroxine ingestion does not affect the circadian rhythm of TSH and iodothyronine secretion, and hence, testing the thyroid profile of the patients in the morning after ingesting levothyroxine at night bears no significance in the outcome of the study.
Keeping these facts in mind, this study was planned to compare the efficacy of morning versus bedtime dose of thyroxine in patients of hypothyroidism.
All patients were having Hashimoto's thyroiditis as underlying cause of hypothyroidism. A written consent was taken from all patients. Patients in group 1 were given levothyroxine in the morning minimum half an hour before breakfast, and in group 2 the drug was given minimum 2 hours after dinner.
None of the patients used medication known to interfere with levothyroxine absorption, nor were they known to have gastro-intestinal disease. Pregnant and postpartum patients with hypothyroidism were not included in either group. Initial dosage was calculated as 1. The study was carried for a time period of 12 weeks, and assessment of quality of life by RAND- Research and Development 36 scoring system [ 11 ] and clinical profile according to the clinical scores given by Billewicz et al.
Biochemical parameters were assessed at baseline before start of treatment and at the end of six, and 12 weeks. TSH normal range 0. Lipid profile was assessed by Konelab 30i using analyzing kits by Randox. Patients were studied on the basis of change in clinical symptoms at presentation, improvement in Quality of life and change in the biochemical parameters with special reference to thyroid function tests and lipid profile.
Clinical symptoms were scored according to the scoring system given by Billewicz et al. The scale score ranged from 0 to for every subscale, with a higher outcome meaning a better health status.
Primary end point was a change in the thyroid profile of the subjects and achievement of euthyroidism in each group measured at the end of six and 12 weeks. Secondary end points of the study were change in QoL, thyroid symptom score, and lipid profile.
For calculation of sample size, results from the pilot study conducted by Bolk et al. Z test was used to compare the difference in mean of free T3, free T4, and lipid profile between each group at the beginning, six and 12 weeks.
Paired t -test was used to assess the intragroup change at six and 12 weeks. The value of TSH in either group did not follow Gaussian data distribution on followup as most of the data were clustered in a narrow range in both the groups at 6 weeks and 12 weeks.
Hence, nonparametric tests: Wilcoxon two-sample test was applied for intergroup comparison and Wilcoxon sign-rank test was applied for intragroup comparison. For intergroup comparison of total score of clinical signs and symptoms and QoL, Wilcoxon two-sample test was applied.
For intragroup comparison of total score of clinical signs and symptoms and QoL, Wilcoxon sign-rank test was applied. The mean age of patients in group 1 was At the end of 12 weeks the mean weight was It was seen that at the end of 6 weeks, 32 At the end of 12 weeks, 70 No patient in either group had a low serum TSH at either 6 or 12 weeks. We also analyzed the secondary outcomes of the study in both of the groups.
However, when Group 1 was compared to Group 2, there was no significant statistical difference. Serum triglyceride levels were reduced by Your Privacy Rights. To change or withdraw your consent choices for VerywellHealth. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page.
These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification. I Accept Show Purposes. Thyroid Disease Healthcare Provider Discussion Guide Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.
Download PDF. Email the Guide Send to yourself or a loved one. Sign Up. What Your Healthcare Provider May Recommend If you do take a T3 drug, your healthcare provider may recommend a time-released or sustained release formulation, or splitting your dose and taking your medication several times throughout the day. Frequently Asked Questions What can happen if I eat right after taking my thyroid medications?
How long does it take for thyroid medication to work? Learn More: Symptoms of Hypothyroidism. What foods can interfere with thyroid medication?
Was this page helpful? Thanks for your feedback! What are your concerns? Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. So, you should take these particular drugs four hours before or after taking your thyroid medication, according to the U.
National Library of Medicine. Most other medication can typically be taken 45 minutes to an hour after your hypothyroidism treatment , Bianco says. Medications and Supplements to Consider and Avoid. Some medication will affect the way your thyroid hormone is absorbed, including birth control pills , estrogen , testosterone , seizure drugs, and some depression medication , according to the American Thyroid Association ATA.
Likewise, any time you stop taking these drugs or make any changes, your thyroid hormone dose may need to be adjusted, and you should see your healthcare provider then, too. Per the ATA , every brand and generic thyroid medication contains the same amount of thyroid replacement hormone.
However, many endocrinologists believe that there is a variation in hormone content among the various brands, and that there are additional factors that can interfere with how the hormone is absorbed with each one, notes the ADA. Therefore, when getting a prescription filled at the pharmacy, you should not change from one brand to another, from a brand name to a generic, or from one generic to another without first checking with your doctor.
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