Supplements or food -> drug interactions

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SUMMARY

The discussion focuses on the critical issue of supplement and drug interactions, particularly highlighting the dangers of combining certain supplements with medications. Notably, grapefruit is identified as a significant inhibitor of the CYP3A4 enzyme, which can dangerously increase the bioavailability of various drugs, leading to potential overdoses. The Medscape Drug Interaction Checker is recommended as a tool for identifying these interactions, although users are cautioned about its limitations, especially when using outdated browsers. Specific examples include the adverse effects of combining statins with grapefruit and the interaction between Levothyroxine and Calcium Carbonate.

PREREQUISITES
  • Understanding of CYP3A4 enzyme function and its role in drug metabolism
  • Familiarity with common supplements and their effects on drug interactions
  • Knowledge of the Medscape Drug Interaction Checker tool
  • Awareness of the implications of bioavailability in pharmacology
NEXT STEPS
  • Research the effects of grapefruit on drug metabolism and its interaction with CYP3A4 substrates
  • Explore the Medscape Drug Interaction Checker for various supplement and drug combinations
  • Investigate the pharmacokinetics of Levothyroxine and its contraindications with Calcium Carbonate
  • Learn about other common food-drug interactions that affect medication efficacy
USEFUL FOR

This discussion is beneficial for healthcare professionals, pharmacists, nutritionists, and individuals taking multiple medications or supplements who need to understand potential interactions and their implications for health.

jim mcnamara
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TL;DR
https://reference.medscape.com/drug-interactionchecker finds references for possible interactions of drugs and supplements
Since supplement sales in North America are multi-billion dollar enterprises and many people take one or more supplements, this is a useful way to find out if there is a problem with a supplement interacting with a food or a drug. Supplements are sometimes prescribed, like Coenzyme Q10 for statin induced myalgia.

Examples: some statins and grapefruit are a bad combination, bisacodyl (a laxative) is inactivated when taken with milk.

The interaction can be be to block, to reduce, or to stimulate the drug response.

https://reference.medscape.com/drug-interactionchecker

It is interesting to play with. It has some limits.
 
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Grapefruit is a notoriously bad actor for increasing the rate of uptake for a bunch of drugs...anybody know why?
 
You asked
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.669.7074&rep=rep1&type=pdf
It is well known that grapefruits and grapefruit juice (GFJ) cause clinically important inhibition of the activity of intestinal CYP3A subfamily, mainly of the CYP3A4 form, and thus increases the oral bioavailability of many CYP3A4 substrates that undergo high presystemic metabolism even if consumed in normal quantities
Short answer: it speeds up the effects of an enzyme group. Which in turn increases the absorption rate of several groups of chemically similar drugs. And speeds up their biochemical effects. Sometimes dangerously.

Think: overdose

This is the opposite of blocking, the result is like taking too many meds orally at one time. From taking the correct dose.
 
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If you are running an old browser, DO NOT BELIEVE THE GIVEN RESPONSE OF 'No Result' or 'No Interactions Found'.

I tried various combinations of Levothyroxine with Calcium Carbonate and received 'No Result' and 'No Interactions Found' using Firefox 43.0.1.

The information sheet that comes with Levothyroxine specifically warns against that combination.
 
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