Drug Interactions between levothyroxine and Nitrostat Tablets
This report displays the potential drug interactions for the following 2 drugs:
- levothyroxine
- Nitrostat Tablets (nitroglycerin)
Interactions between your drugs
No interactions were found between levothyroxine and Nitrostat Tablets. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.
levothyroxine
A total of 225 drugs are known to interact with levothyroxine.
- Levothyroxine is in the drug class thyroid drugs.
- Levothyroxine is used to treat the following conditions:
Nitrostat Tablets
A total of 257 drugs are known to interact with Nitrostat Tablets.
- Nitrostat tablets is in the following drug classes: antianginal agents, vasodilators.
- Nitrostat tablets is used to treat the following conditions:
Drug and food interactions
levothyroxine food
Applies to: levothyroxine
ADJUST DOSING INTERVAL: Consumption of certain foods as well as the timing of meals relative to dosing may affect the oral absorption of T4 thyroid hormone (i.e., levothyroxine). T4 oral absorption is increased by fasting and decreased by foods such as soybean flour (e.g., infant formula), cotton seed meal, walnuts, dietary fiber, calcium, and calcium fortified juices. Grapefruit or grapefruit products may delay the absorption of T4 thyroid hormone and reduce its bioavailability. The mechanism of this interaction is not fully understood.
MANAGEMENT: Some manufacturers recommend administering oral T4 as a single daily dose, on an empty stomach, one-half to one hour before breakfast. In general, oral preparations containing T4 thyroid hormone should be administered on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in serum levels. Foods that may affect T4 absorption should be avoided within several hours of dosing if possible. Consult local guidelines for the administration of T4 in patients receiving enteral feeding.
References
- (2002) "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical
- (2022) "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals
- Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67
nitroglycerin food
Applies to: Nitrostat Tablets (nitroglycerin)
MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.
MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.
References
- Sternbach H (1991) "Fluoxetine-associated potentiation of calcium-channel blockers." J Clin Psychopharmacol, 11, p. 390-1
- Shook TL, Kirshenbaum JM, Hundley RF, Shorey JM, Lamas GA (1984) "Ethanol intoxication complicating intravenous nitroglycerin therapy." Ann Intern Med, 101, p. 498-9
- Feder R (1991) "Bradycardia and syncope induced by fluoxetine." J Clin Psychiatry, 52, p. 139
- Ellison JM, Milofsky JE, Ely E (1990) "Fluoxetine-induced bradycardia and syncope in two patients." J Clin Psychiatry, 51, p. 385-6
- Rodriguez de la Torre B, Dreher J, Malevany I, et al. (2001) "Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients." Ther Drug Monit, 23, p. 435-40
- Cerner Multum, Inc. "Australian Product Information."
- Pacher P, Kecskemeti V (2004) "Cardiovascular side effects of new antidepressants and antipsychotics: new drugs, old concerns?" Curr Pharm Des, 10, p. 2463-75
- Andrews C, Pinner G (1998) "Postural hypotension induced by paroxetine." BMJ, 316, p. 595
levothyroxine food
Applies to: levothyroxine
ADJUST DOSING INTERVAL: Concurrent administration of calcium-containing products may decrease the oral bioavailability of levothyroxine by one-third in some patients. Pharmacologic effects of levothyroxine may be reduced. The exact mechanism of interaction is unknown but may involve nonspecific adsorption of levothyroxine to calcium at acidic pH levels, resulting in an insoluble complex that is poorly absorbed from the gastrointestinal tract. In one study, 20 patients with hypothyroidism who were taking a stable long-term regimen of levothyroxine demonstrated modest but significant decreases in mean free and total thyroxine (T4) levels as well as a corresponding increase in mean thyrotropin (thyroid-stimulating hormone, or TSH) level following the addition of calcium carbonate (1200 mg/day of elemental calcium) for 3 months. Four patients had serum TSH levels that were higher than the normal range. Both T4 and TSH levels returned to near-baseline 2 months after discontinuation of calcium, which further supported the likelihood of an interaction. In addition, there have been case reports suggesting decreased efficacy of levothyroxine during calcium coadministration. It is not known whether this interaction occurs with other thyroid hormone preparations.
MANAGEMENT: Some experts recommend separating the times of administration of levothyroxine and calcium-containing preparations by at least 4 hours. Monitoring of serum TSH levels is recommended. Patients with gastrointestinal or malabsorption disorders may be at a greater risk of developing clinical or subclinical hypothyroidism due to this interaction.
References
- Schneyer CR (1998) "Calcium carbonate and reduction of levothyroxine efficacy." JAMA, 279, p. 750
- Singh N, Singh PN, Hershman JM (2000) "Effect of calcium carbonate on the absorption of levothyroxine." JAMA, 283, p. 2822-5
- Csako G, McGriff NJ, Rotman-Pikielny P, Sarlis NJ, Pucino F (2001) "Exaggerated levothyroxine malabsorption due to calcium carbonate supplementation in gastrointestinal disorders." Ann Pharmacother, 35, p. 1578-83
- Neafsey PJ (2004) "Levothyroxine and calcium interaction: timing is everything." Home Healthc Nurse, 22, p. 338-9
Therapeutic duplication warnings
No warnings were found for your selected drugs.
Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.
See also
Drug Interaction Classification
Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. | |
No interaction information available. |
Further information
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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