Drug Interactions between magnesium citrate and Synthroid

The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication. Therefore, levothyroxine should be taken on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in blood levels, which may alter its effects. In addition, absorption of levothyroxine may be decreased and/or delayed by foods such as soybean flour, cotton seed meal, walnuts, dietary fiber, calcium, calcium fortified juices and grapefruit or grapefruit juice. These foods should be avoided within several hours of dosing if possible. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Using multivitamin with minerals together with levothyroxine may decrease the effects of levothyroxine. You should separate the administration of levothyroxine and multivitamin with minerals by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

The use of thyroid hormones is contraindicated in patients with uncorrected adrenal insufficiency. Thyroid hormones increase tissue demand for adrenocortical hormones and may precipitate acute adrenal crisis. In patients with controlled adrenal insufficiency or other endocrine disorders, therapy for these concomitant disorders may need to be adjusted following thyroid replacement, since hypothyroidism often obscure or diminish the signs and symptoms of these conditions. Clinical monitoring of thyroid and adrenal function as well as any other appropriate endocrine function is recommended during thyroid hormone therapy.

The use of laxatives is contraindicated in patients with intestinal obstruction disorders. Patients with intestinal obstruction disorders may need their underlying condition treated to correct the constipation. Some laxatives require reduction in the colon to their active form to be effective which may be a problem in patients with intestinal obstruction.

Thyroid hormones cause increases in myocardial contractility and heart rate as a result of increased metabolic demands and oxygen consumption. Therapy with thyroid hormones should be administered cautiously and initiated at reduced dosages in patients with cardiovascular disorders such as angina, coronary artery disease, and hypertension. Clinical monitoring of cardiovascular function is recommended. If chest pain or exacerbation of cardiovascular disease occurs, the dosage of thyroid hormone should be reduced, even at the expense of achieving euthyroid state. Thyroid hormones should not be administered to patients with an acute myocardial infarction that is not complicated by hypothyroidism.

Thyroid hormones cause increases in myocardial contractility and heart rate as a result of increased metabolic demands and oxygen consumption. Therapy with thyroid hormones should be administered cautiously and initiated at reduced dosages in patients with cardiovascular disorders such as angina, coronary artery disease, and hypertension. Clinical monitoring of cardiovascular function is recommended. If chest pain or exacerbation of cardiovascular disease occurs, the dosage of thyroid hormone should be reduced, even at the expense of achieving euthyroid state. Thyroid hormones should not be administered to patients with an acute myocardial infarction that is not complicated by hypothyroidism.

The use of thyroid hormones is contraindicated in patients with untreated thyrotoxicosis of any etiology, since thyroid hormones may exacerbate the condition.

The use of laxatives is contraindicated in patients with inflammatory bowel disease. Patients with inflammatory bowel disease may experience colonic perforation with use of stimulant laxatives.

Magnesium is eliminated by the kidney. The serum concentration of magnesium is increased in patients with renal impairment. Magnesium toxicity includes CNS depression, muscular paralysis, respiratory depression, hypotension and prolonged cardiac conduction time. Disappearance of the patellar reflex is a useful clinical sign of magnesium intoxication. Therapy with magnesium should be administered cautiously and dosages should be modified in patients with compromised renal function. Clinical monitoring of serum magnesium levels is recommended.

Since hypothyroidism often obscure or diminish the signs and symptoms of endocrine disorders such as diabetes mellitus or diabetes insipidus, thyroid replacement therapy may aggravate the intensity of symptoms associated with these conditions. Patients with endocrine disorders should be monitored more closely during thyroid hormone therapy, and their medication regimen adjusted accordingly. If thyroid medication is later discontinued, a downward readjustment of insulin or oral hypoglycemic agent may be necessary in patients with diabetes mellitus to avoid hypoglycemia.

Since hypothyroidism often obscure or diminish the signs and symptoms of endocrine disorders such as diabetes mellitus or diabetes insipidus, thyroid replacement therapy may aggravate the intensity of symptoms associated with these conditions. Patients with endocrine disorders should be monitored more closely during thyroid hormone therapy, and their medication regimen adjusted accordingly. If thyroid medication is later discontinued, a downward readjustment of insulin or oral hypoglycemic agent may be necessary in patients with diabetes mellitus to avoid hypoglycemia.

Thyroid hormones may alter the seizure threshold. Seizures have been reported rarely following the initiation of levothyroxine therapy. Therapy with thyroid hormones should be administered cautiously in patients predisposed to seizures.