Synthroid (Levothyroxine Sodium) - Summary

SYNTHROID SUMMARY

SYNTHROID® (levothyroxine sodium tablets, USP) contain synthetic crystalline L-3,3',5,5'-tetraiodothyronine sodium salt [levothyroxine (T₄) sodium]. Synthetic T₄ is identical to that produced in the human thyroid gland.

Levothyroxine sodium is used for the following indications:

Hypothyroidism --As replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis. Specific indications include: primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) hypothyroidism and subclinical hypothyroidism. Primary hypothyroidism may result from functional deficiency, primary atrophy, partial or total congenital absence of the thyroid gland, or from the effects of surgery, radiation, or drugs, with or without the presence of goiter.

Pituitary TSH Suppression --In the treatment or prevention of various types of euthyroid goiters (see WARNINGS and PRECAUTIONS), including thyroid nodules (see WARNINGS and PRECAUTIONS), subacute or chronic lymphocytic thyroiditis (Hashimoto's thyroiditis), multinodular goiter (see WARNINGS and PRECAUTIONS) and, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

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NEWS HIGHLIGHTS

Media Articles Related to Synthroid (Levothyroxine)

levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid
Source: MedicineNet Pendred Syndrome Specialty [2007.11.16]
Title: levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid
Category: Medications
Created: 12/31/1997
Last Editorial Review: 11/16/2007

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Published Studies Related to Synthroid (Levothyroxine)

Chromosome translocation frequency after radioiodine thyroid remnant ablation: a comparison between recombinant human thyrotropin stimulation and prolonged levothyroxine withdrawal. [2009.09]
BACKGROUND: Thyroid remnant ablation of differentiated thyroid carcinoma (DTC) patients is traditionally performed after levothyroxine withdrawal. Recombinant human TSH (rhTSH) administration increases serum TSH levels without inducing hypothyroidism. AIM: The aim of the study was to investigate the frequency of chromosome translocations in DTC patients after the first (131)I therapeutic dose and compare the frequency of translocations between DTC patients off levothyroxine and those receiving rhTSH... CONCLUSIONS: Our preliminary data show that in hypothyroid status (131)I ablation therapy induces a higher translocation rate, especially in chromosomes 4 and 8. This finding, in agreement with previous dosimetric reports, suggests that whereas inducing a low extrathyroid exposure, rhTSH reduces the potential risk of chromosomal aberration associated with blood irradiation.

Serum leptin in overt and subclinical hypothyroidism: effect of levothyroxine treatment and relationship to menopausal status and body composition. [2009.05]
BACKGROUND: The relationship between thyroid status, including subclinical hypothyroidism (SH) and serum leptin is controversial or uncertain. Therefore we evaluated serum leptin in SH and overt hypothyroidism (OH) and determined the effects of levothyroxine (LT(4)) replacement on serum leptin in these disorders... CONCLUSIONS: Serum leptin concentrations are elevated in postmenopausal women with SH or OH. A relationship between thyroid status and serum leptin is further supported by the fact that LT(4) treatment, to restore the EU status, reduced serum leptin levels in OH in the absence of significant effects on BMI. In women, hypothyroidism influences either leptin secretion or degradation and this effect is more pronounced in postmenopausal than in premenopausal women.

Efficacy of combined levothyroxine and liothyronine as compared with levothyroxine monotherapy in primary hypothyroidism: a randomized controlled trial. [2009]
OBJECTIVES: To examine the efficacy of combination therapy with levothyroxine and liothyronine in improvement of general health, psychological problems, and metabolic status in primary hypothyroidism... CONCLUSIONS: The data do not support the hypothesis that combined therapy improves the well-being and general health of patients.

Lipid profile in different degrees of hypothyroidism and effects of levothyroxine replacement in mild thyroid failure. [2008.04]
The aim of this study was to evaluate the lipid profile of patients with different degrees of hypothyroidism and the effect of levothyroxine replacement in subclinical hypothyroidism (SH). Initially, a cross-sectional study was performed with 226 participants [SH = 133 participants, manifest hypothyroidism (MH) = 23 participants, and euthyroidism (EU) = 70 participants]...

Levothyroxine in euthyroid autoimmune thyroiditis and type 1 diabetes: a randomized, controlled trial. [2007.05]
CONTEXT: Patients with type 1 diabetes (T1D) have an increased risk of autoimmune thyroiditis (AIT). OBJECTIVE: Our objective was to determine whether levothyroxine (l-T(4)) treatment prevents the clinical manifestation of AIT in euthyroid subjects with T1D... CONCLUSIONS: In this study in euthyroid patients with AIT and T1D, l-T(4) treatment reduced thyroid volume but had no effect on thyroid function and serum autoantibody levels.

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Clinical Trials Related to Synthroid (Levothyroxine)

Fasting Study of Levothyroxine Sodium Tablets 200 mg to Synthroid Tablets 200 mg [Completed]
The objective of this study was to investigate the bioequivalence of Mylan's levothyroxine sodium 200 μg tablets to Abbott's Synthroid® 200 μg tablets following a single 600 μg (3 x 200 μg) dose administration in healthy volunteers under fasting conditions. Twenty-nine healthy, non-smoking, subjects between the ages of 18 and 47 completed this open-label, randomized, two-period, two-treatment, single-dose crossover study conducted by Dr. James D. Carlson at PRACS Institute, Ltd., Fargo, ND. Statistical analysis of the data revealed that 90% confidence intervals were within the acceptable bioequivalent range of 80% and 125% for the natural log transformed parameters LNAUC0-48hr and LNCPEAK for baseline corrected total L-thyroxine. This study demonstrated that Mylan's 200 μg levothyroxine sodium tablets are bioequivalent to Abbott's Synthroid® 200 μg tablets following a single, oral 600 μg (3 x 200 μg) dose under fasting conditions

Fasting Study of Levothyroxine Sodium Tablets 300 μg to Synthroid® Tablets 300 μg [Completed]
The objective of this study was to investigate the bioequivalence of Mylan's levothyroxine sodium 300 μg tablets to Abbott's Synthroid® 300 μg tablets following a single 600 μg (2 x 300 μg) dose administered in healthy volunteers under fasting conditions. Single-dose pharmacokinetic parameters for baseline corrected total L-thyroxine and non-baseline corrected total L-triiodothyronine were calculated using noncompartmental techniques.

Fasting Study of Levothyroxine Sodium Tablets 300 Mcg to Synthroid® Tablets 300 Mcg [Completed]
The objective of this study was to investigate the bioequivalence of Mylan's levothyroxine sodium 300 mcg tablets to Abbott's Synthroid® 300 mcg tablets following a single, oral 600 mcg dose (2 × 300 mcg) administered under fasting conditions.

Fasting Study of Levothyroxine Sodium Tablets 300 μg to Levothroid® Tablets 300 μg [Completed]
The objective of this study was to investigate the bioequivalence of Mylan's levothyroxine sodium 300 μg tablets to Lloyd's Levothroid® 300 μg tablets following a single 600 μg (2 x 300 μg) dose administered in healthy adult volunteers under fasting conditions. Statistical analysis of the data revealed that 90% confidence intervals were within the acceptable bioequivalent range of 80% and 125% for the natural log transformed parameters LNAUC0-48hr and LNCPEAK for baseline corrected total levothyroxine.

Phase 4 Study in Secondary Hypothyroidism: Body Weight Adapted Thyroxin Treatment and Triiodothyronine Supplementation [Completed]
The purpose of this study is to determine whether a body weight adjusted dose of thyroxin is superior to treatment guided by laboratory results of thyroxin hormones in patients with central hypothyroidism. Moreover beneficial effects of triiodthyronine supplementation are investigated.

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PATIENT REVIEWS / RATINGS / COMMENTS

Synthroid review by 46 year old female patient
		Rating
Overall rating:
Effectiveness:		Considerably Effective
Side effects:		No Side Effects
		Treatment Info
Condition / reason:		hypothyroid
Dosage & duration:		25 mcg (dosage frequency: 1/day) for the period of for the last 9 mos
Other conditions:		mild hypertension
Other drugs taken:		lexapro, welbutrin, nexium, Benicar
		Reported Results
Benefits:		Increased energy; I happened to be without the drug for one week, and felt absolutely terrible - like I was completely knocked down.
Side effects:		no side effects that i can remember.
Comments:		The doctor ran a series of blood/chemical tests - thyroid, testosterone and DHEA levels. All were somewhat low, the synthroid in particular. We've started out with fairly low levels of each.

Synthroid review by 28 year old female patient
		Rating
Overall rating:
Effectiveness:		Highly Effective
Side effects:		No Side Effects
		Treatment Info
Condition / reason:		hypothyroidism
Dosage & duration:		37 1/2 mcg (dosage frequency: 1 1/2 pills once a day) for the period of so far, about 7 months
Other conditions:		none
Other drugs taken:		none
		Reported Results
Benefits:		i have mild hypothyroidism, so i wasn't necessarily aware of what having an underfunctioning was doing to my body. still, i was able to detect changes (for the better) after taking synthroid for a few months. the primary benefit i aw was HIGHLY HIGHLY improved concentration, which has made school/work such a pleasure. i think my metabloism also improved slightly.
Side effects:		none, as far as i could see.
Comments:		take your pill everyday at the same time. i found that morning is best, because you need to wait an hour to eat after taking the pill. i take it right when i wake up, then get ready, and then have breakfast right at the one hour mark.

Synthroid review by 36 year old female patient
		Rating
Overall rating:
Effectiveness:		Ineffective
Side effects:		Extremely Severe Side Effects
		Treatment Info
Condition / reason:		under active thyroid
Dosage & duration:		from 50 mcg to 112 mcg (dosage frequency: ones a day or split to two portions) for the period of 21 months
Other conditions:		non
Other drugs taken:		contraceptives MIN-OVRAL
		Reported Results
Benefits:		improved some symptoms: cold intolerance; carbs cravings; gives energy for a short periods of time (2-3 weeks) after increasing the dose;
Side effects:		extreme fatigue; 38 LBS weight gain; mood swings; muscle weakness; excessive sleep; irritability; intolerance to excersise; tiredness and heaviness all over the body; brain forg; slow reactions
Comments:		I was taking 50 mcg of generic Synthroid at the mornings 30-40 minutes before breakfast. The dose was increased gradually every 2 month as my thyroid was drastically decreasing its activity and symptoms reoccured. The doses of 100 mcg and later 112 mcg were taken sublingually twice a day 30-40 minutes before breakfast and lunch. Contraceptives MIN-OVRAL and supplements of Ca, Mg and iron were taken at the evening to avoid the interractions.