Metformin with Guar Gum Interaction Details

Brand Names Associated with Metformin

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 05, 2023

Interaction Effect

Decreased effectiveness of metformin

Interaction Summary

Concomitant administration of guar gum and metformin reduced the rate and extent of absorption of metformin in healthy subjects. Guar gum, acting as a gel, delays gastric emptying and subsequent delivery of metformin to its site of absorption . Guar gum should be administered at least 6 hours after metformin in order to retain maximum effectiveness of metformin, as metformin is absorbed within 6 hours of administration . Guar gum may also delay absorption of glucose from meals, leading to less postprandial hyperglycemia . Closely monitor blood glucose levels and signs and symptoms of hypoglycemia when both agents are used together.

Severity

Moderate

Onset

Rapid

Evidence

Probable

How To Manage Interaction

Administer guar gum at least 6 hours after metformin to retain maximal effectiveness of metformin. Closely monitor blood glucose levels and signs and symptoms of hypoglycemia in patients taking guar gum and metformin.

Mechanism Of Interaction

Delayed gastric emptying by guar gum

Literature Reports

A) Guar gum administered with metformin significantly decreased metformin AUC and slightly lowered blood glucose levels for 6 hours in 6 volunteers without diabetes. Volunteers included 5 men and one woman ages 24 to 32 years and within 10% of their ideal body weight. Metformin 1700 mg was prescribed followed by a prescribed meal. Two days later, the same regimen was repeated with the addition of guar gum 10 grams (powder stirred in water) taken together with metformin. Within one hour of concomitant administration, metformin blood levels were reduced by approximately 40% and continued at reduced levels for another 6 hours. Bioavailability was also reduced, as AUC decreased from 1025 +/- 76 milligrams per liter per hour (mg/L/hour) to 621 +/- 57 mg/L/hour (p less than 0.001). Following metformin and guar gum intake, blood glucose levels were slightly lower for the next 6 hours than when metformin was taken alone .

B) Guar gum significantly reduced urinary glucose output in 9 patients with diabetes. Patients supplemented their home diet (n equal to 4) or metabolic ward diet (n equal to 5) with guar gum 25 grams daily for 5 or 7 days. Six patients were treated with insulin (doses ranged from 38 units/day to 84 units/day), while one was controlled with diet alone. In the home diet studies, guar gum was incorporated into bread, canned soup, and fruit juice, and taken at the beginning of meals. During control periods, equal amounts of bread, canned soup, and fruit juice were taken. In metabolic ward studies, guar gum was given in bread, soup, and mashed potatoes. Urinary glucose output decreased by 46% (p less than 0.05) with the home diet and 54% (p less than 0.01) with the metabolic ward diet. Mean urinary glucose output for the home diet was reduced from 26.3 +/- 11.5 grams/24 hours to 14.1 +/- 9.8 grams/24 hours (p less than 0.05). Mean urinary glucose output for the metabolic ward diet was reduced from 29.0 +/- 9.2 grams/24 hours to 13.3 +/- 7.3 grams/24 hours (p less than 0.01). One study was stopped due to recurrent hypoglycemic episodes during the guar gum treatment period. Three patients found it necessary to reduce their insulin dose temporarily after the study, though they were taking their original dose within 2 weeks .

Metformin Overview

• Metformin is used alone or with other medications, including insulin, to treat type 2 diabetes (condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood). Metformin is in a class of drugs called biguanides. Metformin helps to control the amount of glucose (sugar) in your blood. It decreases the amount of glucose you absorb from your food and the amount of glucose made by your liver. Metformin also increases your body's response to insulin, a natural substance that controls the amount of glucose in the blood. Metformin is not used to treat type 1 diabetes (condition in which the body does not produce insulin and therefore cannot control the amount of sugar in the blood).

• Over time, people who have diabetes and high blood sugar can develop serious or life-threatening complications, including heart disease, stroke, kidney problems, nerve damage, and eye problems. Taking medication(s), making lifestyle changes (e.g., diet, exercise, quitting smoking), and regularly checking your blood sugar may help to manage your diabetes and improve your health. This therapy may also decrease your chances of having a heart attack, stroke, or other diabetes-related complications such as kidney failure, nerve damage (numb, cold legs or feet; decreased sexual ability in men and women), eye problems, including changes or loss of vision, or gum disease. Your doctor and other healthcare providers will talk to you about the best way to manage your diabetes.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.