Related Experiment Video
Updated: Jul 12, 2026
07:02
In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice
Published on: August 23, 2019
New medications which decrease levothyroxine absorption.
Jennifer John-Kalarickal1, Gwen Pearlman, Harold E Carlson
1Endocrinology Division, Department of Medicine, Stony Brook University School of Medicine, Stony Brook, New York 11794-8154, USA.
Thyroid : Official Journal of the American Thyroid Association
|August 30, 2007
Summary
Sevelamer hydrochloride and chromium picolinate reduce levothyroxine absorption. Hypothyroid patients should separate these medications from their thyroid hormone replacement therapy by several hours to ensure efficacy.
Area of Science:
- Pharmacology
- Endocrinology
- Gastroenterology
Background:
- Levothyroxine absorption can be impaired by medications forming insoluble complexes in the gut.
- Understanding drug-drug interactions is crucial for effective thyroid hormone replacement therapy.
Purpose of the Study:
- To investigate the acute effects of sevelamer hydrochloride, chromium picolinate, and ezetimibe on levothyroxine absorption.
- To identify potential interactions impacting thyroid hormone bioavailability.
Main Methods:
- A study involving seven healthy volunteers assessing levothyroxine sodium absorption.
- Co-administration of levothyroxine with sevelamer hydrochloride, chromium picolinate, or ezetimibe.
- Measurement of serum thyroxine levels over a 6-hour period post-ingestion.
Main Results:
- Sevelamer hydrochloride significantly reduced the area under the serum thyroxine concentration curve (p < 0.05).
- Chromium picolinate also significantly decreased serum thyroxine levels (p < 0.05).
- Ezetimibe demonstrated no significant impact on levothyroxine absorption.
Conclusions:
- Sevelamer hydrochloride and chromium picolinate interfere with levothyroxine absorption.
- Patients on thyroid hormone therapy should separate intake of these medications from levothyroxine by several hours.
- Ezetimibe does not appear to affect levothyroxine bioavailability.
Related Concept Videos
01:19Oral Hypoglycemic Agents: α-Glucosidase Inhibitors
α-glucosidase inhibitors, including acarbose (Precose), miglitol (Glyset), and voglibose (Voglib) (primarily available in Asia), are drugs that control blood sugar levels by delaying the digestion of starch and disaccharides. They achieve this by inhibiting α-glucosidase enzymes in the intestine, which slow the absorption of carbohydrates in the intestine, which in turn leads to a prolonged release of the glucoregulatory hormone GLP-1 from intestinal L-cells.
Acarbose and miglitol are typically...
Acarbose and miglitol are typically...
01:19Antiasthma Drugs: Leukotriene Modifiers
Leukotriene modifiers, or cysteinyl leukotriene receptor antagonists, are medications used to manage chronic asthma. These agents target specific inflammatory mediators produced during arachidonic acid metabolism, an essential process in generating inflammation in the body.
Leukotriene modifiers work through two distinct mechanisms:
Leukotriene modifiers work through two distinct mechanisms:
01:20Lipid-Lowering Drugs: Statins and Miscellaneous Agents
Hyperlipidemia, a medical condition often referred to as high cholesterol, is characterized by abnormally elevated levels of lipids in the bloodstream. When present in excess, these lipids, specifically cholesterol and triglycerides, can lead to serious health complications, often involving cardiovascular diseases. Illnesses like atherosclerosis, heart attacks, and pancreatitis have all been linked to untreated hyperlipidemia. This means controlling and regulating cholesterol and triglyceride...
01:21Drugs for Treatment of Constipation-Predominant IBS
Pharmacological therapies for IBS-C are designed to alleviate abdominal discomfort and enhance bowel function. In patients with IBS-C, fiber supplements may help soften stools and decrease straining, but may also lead to increased gas production and bloating. Osmotic laxatives like milk of magnesia are frequently used to soften stools and increase stool frequency in IBS-C patients. In addition, two drugs approved for use in severe IBS-C adult cases are linaclotide (Linzess) and lubiprostone...
01:27Bioavailability Enhancement: Drug Permeability Enhancement
After oral administration, poor permeability often limits the rate at which drugs are absorbed through the intestinal epithelium. Enhancing drug permeability is crucial for effective therapy, and several strategies have been developed to overcome this challenge.One effective strategy involves the use of lipid-based formulations. These formulations enhance dissolution and solubility, targeting physiological mechanisms to increase drug absorption. This includes stimulating bile salt secretion,...
01:25Factors Influencing Drug Absorption: Disease States and Pharmacology
Multiple disease states can significantly influence the oral drug absorption process by affecting blood flow and the functionality of the gastrointestinal (GI) system. Various GI diseases, including conditions that alter GI motility, such as diarrhea, decreased acid secretions (achlorhydria), and infections, have been associated with reduced drug absorption.
Substances such as alcohol and specific drugs, including antineoplastics, can also negatively impact drug absorption. For instance,...
Substances such as alcohol and specific drugs, including antineoplastics, can also negatively impact drug absorption. For instance,...