6 Interactions found for:
Drug Interactions
No drug interactions were found for selected drugs: gabapentin, Synthroid.
This does not necessarily mean no interactions exist. Always consult your healthcare provider.
Drug and Food Interactions
Moderate
Synthroid
+ Food
The following applies to the ingredients: Levothyroxine (found in Synthroid)
The timing of meals relative to your levothyroxine dose can affect 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 by foods such as soybean flour, cotton seed meal, walnuts, dietary fiber, calcium, and calcium fortified juices. 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.
When levothyroxine is given during continuous enteral nutrition (tube feedings) for more than 7 days, the tube feeding should be interrupted for at least one hour before and one hour after the dose of levothyroxine. You may need more frequent blood tests to monitor levothyroxine levels.
The following applies to the ingredients: Levothyroxine (found in Synthroid)
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.
Moderate
Gabapentin
+ Food
The following applies to the ingredients: Gabapentin
Alcohol can increase the nervous system side effects of gabapentin such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with gabapentin. Do not use more than the recommended dose of gabapentin, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.
Drug and Pregnancy Interactions
Major
Gabapentin
+ Pregnancy
The following applies to the ingredients: Gabapentin
Professional Content
Benefits should clearly outweigh risks
AU TGA pregnancy category: B3
US FDA pregnancy category: Not assigned
Risk Summary: There are no data on the developmental risks associated with use of this drug in pregnant women; in animal studies, developmental toxicity was observed at doses estimated to be similar or lower than those used clinically.
Comments:
-The risk of having a child with a congenital defect as a result of antiepileptic medication is far outweighed by the dangers to the mother and fetus of uncontrolled epilepsy; folic acid supplementation (5 mg) should be started 4 weeks prior to and continued for 12 weeks after conception.
-Women of childbearing potential should receive counseling on the risk of fetal abnormalities with use of antiepileptic drugs (AEDs) during pregnancy; AEDs should generally be continued during pregnancy utilizing monotherapy at the lowest effective dose as this has been shown to minimize risks of fetal abnormalities compared to combination AED therapy.
-A pregnancy exposure registry is available.
Animal studies have revealed evidence of developmental toxicity (increased fetal skeletal and visceral abnormalities, and increased embryofetal mortality) when administered at doses similar to, or lower than expected clinical doses. In rats, an increased incidence of hydroureter and/or hydronephrosis have been observed in offspring at all doses, the lowest dose being similar to the maximum recommended human dose on a mg/m2 basis. This drug crosses the human placenta. From the limited amount of data in human pregnancy, it is not possible to inform an associated increased risk of congenital malformations because epilepsy itself and the presence of concomitant antiepileptic medicinal products have their own risks. There are no controlled data in human pregnancy.
To provide information regarding the effects of in utero exposure to this drug, pregnant patients should be encouraged to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334 and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.
AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.
References
- "Product Information. Neurontin (gabapentin)." Parke-Davis PROD (2001):
- Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
- Cerner Multum, Inc. "Australian Product Information." O 0
- "Product Information. Horizant (gabapentin)." GlaxoSmithKline (2021):
- "Product Information. Gralise (gabapentin)." Depomed Inc (2021):
Minor
Synthroid
+ Pregnancy
The following applies to the ingredients: Levothyroxine (found in Synthroid)
Professional Content
Use is considered acceptable
AU TGA pregnancy category: A
US FDA pregnancy category: Not Assigned
Risk Summary: No increased rates of major birth defects or miscarriages have been reported with use during pregnancy; untreated hypothyroidism during pregnancy is associated with risks to the mother and fetus
Comments:
-Thyroid replacement therapy should not be discontinued during pregnancy; hypothyroidism diagnosed during pregnancy should be promptly treated.
-Monitor TSH levels and adjust doses as needed.
Animal studies have not been conducted. There is a long history of using this drug in pregnant women and this experience has not shown increased rates of fetal malformations, miscarriages or other adverse maternal or fetal outcomes. Hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, pre-eclampsia, stillbirth and premature delivery. Maternal hypothyroidism may have an adverse effect on fetal neurocognitive development. Pregnant women taking this drug should have their TSH measured during each trimester and dose adjusted as appropriate. Patients will generally return to their pre-pregnancy dose after delivery. There are no controlled data in human pregnancy.
AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.
US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.
References
- "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical PROD (2002):
- Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
- Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp" (2006):
- Cerner Multum, Inc. "Australian Product Information." O 0
Drug and Breastfeeding Interactions
Major
Gabapentin
+ Breastfeeding
The following applies to the ingredients: Gabapentin
Professional Content
Benefits should clearly outweigh risks
Excreted into human milk: Yes
Comments:
-Breastfed infants should be monitored for drowsiness, adequate weight gain, and developmental milestones, especially when used in combination with other anticonvulsant or psychotropic drugs and in younger, exclusively breastfed infants.
-Some authorities suggest discontinuing nursing or discontinuing use of this drug while breastfeeding due to the potential for serious adverse reactions in the breastfed infant.
With maternal doses up to 2.1 g/day, estimated doses for fully breastfed infants are 0.2 to 1.3 mg/kg/day (equivalent to 1.3 to 3.8% of the maternal weight-adjusted dose). An expert panel has deemed this drug is an acceptable choice for refractory restless leg syndrome during lactation. Until more data becomes available, the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for this drug and any potential adverse effects on the breastfed infant from this drug or from the underlying maternal condition.
References
- "Product Information. Neurontin (gabapentin)." Parke-Davis PROD (2001):
- Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
- Cerner Multum, Inc. "Australian Product Information." O 0
- United States National Library of Medicine "Toxnet. Toxicology Data Network. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT" (2013):
- "Product Information. Horizant (gabapentin)." GlaxoSmithKline (2021):
- "Product Information. Gralise (gabapentin)." Depomed Inc (2021):
Minor
Synthroid
+ Breastfeeding
The following applies to the ingredients: Levothyroxine (found in Synthroid)
Professional Content
Use is considered acceptable
Excreted into human milk: Yes
Comments:
-Levothyroxine (T4) is a normal component of human milk; limited data on exogenous replacement doses during breastfeeding have not shown an adverse effect in nursing infants.
-Levothyroxine dose requirements may be increased in the postpartum period compared to prepregnancy requirements in patients with Hashimoto's thyroiditis.
-The presence of thyroid hormone in breast milk does not appear to interfere with neonatal thyroid screening.
References
- "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical PROD (2002):
- Jansson L, Ivarsson S, Larsson I, Ekman R "Tri-iodothyronine and thyroxine in human milk." Acta Paediatr Scand 72 (1983): 703-5
- Moller B, Bjorkhem I, Falk O, Lantto O, Lafsson A "Identification of thyroxine in human breast milk by gas chromatography-mass spectrometry." J Clin Endocrinol Metab 56 (1983): 30-4
- Mizuta H, Amino N, Ichihara K, et al. "Thyroid hormones in human milk and their influence on thyroid function of breast-fed babies." Pediatr Res 17 (1983): 468-71
- Hahn HB, Spiekerman AM, Otto R, Hossalla DE "Thyroid function tests in neonates fed human milk." Am J Dis Child 137 (1983): 220-2
- Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
- Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp" (2006):
- Cerner Multum, Inc. "Australian Product Information." O 0
- United States National Library of Medicine "Toxnet. Toxicology Data Network. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT" (2013):
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.
Switch to: Professional Interactions
| Drug Interaction Classification | |
|---|---|
These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication. |
|
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | 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. |
| Unknown | No interaction information available. |
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