A Snippet: Wind-eze Gel Caps (contain Simeticone - as activated Dimeticone): Can Reduce Absorption of Levothyroxine and other Thyroid Meds

[Foggyme]

Hi All. Doing some research for a forum member and discovered that Wind-eze Gel Caps (an anti-wind agent) contain Simeticone (activated Dimeticone), a drug that can reduce the absorption of levothyroxine (and other thyroid medications).

medicines.org.uk/emc/PIL.26...

Interestingly, information leaflets for other preparations that contain Simeticone (i.e. Windsetlers) do not contain this warning information. Might be that the Wind-eze contains 'activated Dimeticone' and Windsetler just Simeticone - no idea what the difference is and no time to research further right now.

So beware anything containing Simeticone...or activated Dimeticone...or both 😉...according to the PIL, it could impede absorption of thyroid meds.

Thought I'd post here just in case it's something you haven't heard of (though I doubt that 😉).

It certainly surprised me...but that's not difficult 🙄.

👍

[JGBH]

Thank you Foggyme, very useful to know. x

[helvella]

Foggyme,

Thank you for thinking of us!

The list of things that interfere with levothyroxine often appears not much shorter than the BNF.

The quoted passage below suggests it was not reported until 2011.

Drug therapy

Case report

Drug interaction of levothyroxine with infant colic drops

Mihirani Balapatabendi, David Harris, Savitha D Shenoy

Author affiliations

Department of Paediatrics, Leicester Royal Infirmary, UHL NHS Trust, Leicester, UK

Abstract

Infacol (Forest Laboratories UK, Kent, UK) is a widely available over-the-counter preparation used to relieve colic symptoms in neonates and infants. The active ingredient is simeticone. No drug interactions with simeticone are documented in the current summary of product characteristics. The authors report the case of an infant with confirmed congenital hypothyroidism on levothyroxine who experienced a possible drug interaction with simeticone. Despite adequate levothyroxine dosage, thyroid stimulating hormone (TSH) was high, suggesting undertreatment. Questioning revealed the child was taking Infacol drops before feeds while on levothyroxine. The colic drops were immediately discontinued and TSH promptly normalised with a reduction in thyroxine requirement to an age appropriate dosage. Drug interaction of thyroxine with simeticone has not been reported previously and is not listed in the British National Formulary for Children. Clinicians and parents need to be aware of this interaction to avoid unnecessary undertreatment and prevent potential long-term neurological sequelae.

dx.doi.org/10.1136/archdisc...

adc.bmj.com/content/96/9/88...

[Foggyme in reply to helvella]

Bit worrying Helvella 'cause Simeticone appears to be in lots of OTC preparations...and not all appear to carry warnings about the interaction with thyroid meds.

Good job that you folks here are 'in the know' 😉.

Thinking of you...always 😊

[helvella in reply to Foggyme]

143 products listed in the Electronic Medicines Compendium mention simeticone (most likely as an ingredient). And not all medicines are listed.

medicines.org.uk/emc/search...

When people ask if medicine X can be taken with levothyroxine, I always suggest that we cannot trust anything. And the inactive ingredients (excipients) are as likely as the active ingredients to be the cause of the issue.

[Foggyme in reply to helvella]

Grief...what a nightmare...thank goodness I only have B12 deficiency and an autoimmune condition to think about...for now!

'We cannot trust anything'...I become a less trusting and more suspicious creature by the day 😉

[jimh111]

Simeticone does impair the absorption of levothyroxine, the only study I know of is the one posted by helvella. It should be fine if you leave a few hours between the simeticone and levothyroxine (and presumably any other form of thyroid hormone).

Thyroid hormones are lipophillic, they bind to lipids. Simeticone is a non-absorbable lipid. So if you take levothyroxine around the same time it will stick to the simeticone and since simeticone is non-absorbable it will just pass out. Just separate the two medications.