How does food change drug absorption?

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The absorption of the drug depends on the emptying time of the stomach, so the patient should be based on whether the drug is less soluble or long-lasting, but taken on an empty stomach or after a meal. In addition, food can alter drug metabolism and elimination. Conversely, drugs can also affect the metabolism of certain substances in food. So how do drugs and foods interact?

1. Overview

Drug-food interactions can occur with both prescription and over-the-counter (OTC) drugs, including antacids, vitamins, iron pills, herbs, supplements, and beverages.
Some nutrients can bind to drug components, affecting the metabolism of some drugs. In other words, food alters drug absorption, reducing absorption or speeding up elimination.
Not all drugs are affected by food, but many can be affected by your eating habits. Sometimes, taking medicine with food can interfere with the absorption of the medicine by the stomach and intestines. There are also medications that are recommended to be taken with food. Some are only absorbed if you take them with a full meal or even a high-fat meal. Therefore, you should ask your doctor or pharmacist for specific instructions on what to eat before or after taking any medication.

2. Some Drug-Food Interactions

2.1. Warfarin and Vitamin K

Warfarin (Coumadin) is a blood thinner that helps treat and prevent blood clots. Consuming foods rich in vitamin K may decrease the effectiveness of warfarin. The highest levels of vitamin K are found in green leafy vegetables such as: kale, bok choy, spinach, turnip greens, Brussels sprouts, broccoli, green onions, asparagus and bean sprouts.
Doctors recommend that patients do not need to avoid foods containing vitamin K, but instead maintain a regular daily intake. But if they need to lose weight and start eating more green vegetables, the amount of vitamin K will increase. This will counter the anticoagulant effect of warfarin.

2.2. Insulin, diabetes pills and alcohol

Alcohol can increase or prolong the effects of insulin or diabetes control pills, leading to hypoglycemia or low blood sugar. The hypoglycemic effect of alcohol can last from 8 to 12 hours with symptoms including: nervousness, sweating, tremors, intense hunger, weakness, palpitations, confusion, sadness sleep and eventually coma.
Each person can reduce the risk of low blood sugar by having alcohol with a meal or snacking while drinking. Older adults with diabetes can enjoy up to 2 glasses of wine a day as long as:
Approved by a doctor No history of pancreatitis No elevated triglycerides No neurological disease. Also, some diabetes control pills like chlorpropamide (Diabinese) can cause dizziness, flushing, and nausea when taken with alcohol.

2.3. Digoxin, a high fiber and herbal diet

Digoxin (Digitalis, Digitek, Lanoxin) is used to enhance contraction of the heart muscle, slow the heart rate, and promote fluid removal from body tissues.
Dietary fiber, especially insoluble fiber (such as wheat bran) can slow the absorption of digoxin and reduce the effectiveness of the drug. To prevent this, older adults should take the medicine at least 1 hour before meals or 2 hours after meals.
Besides, the use of herbs can also affect digoxin. For example, ginseng can increase blood levels of digoxin by up to 75%, while St. John's Wort reduces it by 25%.
It is important for patients to recognize the signs of digoxin toxicity, including: vision changes, halos around objects, weakness, confusion, dizziness, nausea and vomiting .

2.4. Statins and grapefruit

Statins are highly effective cholesterol-lowering drugs. However, drinking grapefruit juice or eating fresh grapefruit can increase blood levels of statins, leading to the potential side effects of these medications. Side effects of statins include: muscle pain and liver abnormalities as reflected in blood tests.
This type of drug-food interaction is particularly strong with simvastatin (Zocor) and lovastatin (Altoprev), milder with atorvastatin (Lipitor) and nonexistent for pravastatin (Pravachol). So it's important that you check if your prescribed statins interact with grapefruit.

2.5. Calcium and grapefruit blockers

Calcium channel blockers are prescribed for high blood pressure. A natural element found in grapefruit affects the intestinal enzyme CYP3A4, altering the breakdown of calcium channel blockers, possibly increasing blood levels of the drug excessively, as well as increasing the risk of heart disease. serious side effects.
The interaction between grapefruit and calcium blockers is strongest, for example, with felodipine (Plendil), nicardipine (Cardene) and nisoldipine (Sular) and weaker with amlodipine (Norvasc), diltiazem (Cardizem) and nifedipine (Adalat).

2.6. Erectile Dysfunction Pills and Grapefruit

Although unproven, evidence indicates that grapefruit juice has the potential to increase blood levels of the erectile dysfunction drug sildenafil (Viagra). Some men may see this as beneficial, but this condition will cause dangerous headaches, flushing or low blood pressure.

2.7. Acetaminophen and alcohol

The over-the-counter pain reliever acetaminophen has the brand name Tylenol. Consuming more than 2 alcoholic beverages per day can increase the hepatotoxicity of Tylenol, which can occur even when patients take less than 4 grams or 8 Tylenol tablets per day.
This interaction can be especially dangerous in the elderly, as liver function declines with age. A 65-year-old's liver doesn't work like it did at 25.

2.8. Antibiotics and dairy products

Dairy products (such as: milk, yogurt, and cheese) can delay or prevent the absorption of antibiotics such as tetracyclines and ciprofloxacin (Cipro). This is because the calcium in these foods binds with antibiotics in the stomach and upper small intestine to form an insoluble compound.
To avoid the problem that food changes absorption of the drug, doctors often recommend that patients take the medicine 1 hour before meals or take the medicine 2 hours after meals.
However, there is no need to avoid dairy with all antibiotics. For example, metronidazole (Flagyl) should be taken with water or milk to prevent stomach upset.

2.9. Monoamine oxidase inhibitors and Tyramine-containing foods

Foods containing tyramine, such as some red wines, malt beer, smoked fish, aged cheeses and dried fruit - can cause a serious increase in blood pressure when taken with antidepressants monoamine oxidase. This is an older class of antidepressants with serious side effects that are still prescribed today, albeit less commonly.

2.10. Antithyroid drugs and iodine-rich foods

Antithyroid drugs are compounds that interfere with the body's production of thyroid hormone, thereby reducing the symptoms of hyperthyroidism. According to a research group, the iodine-rich diet of Americans reduces the effectiveness of antithyroid drugs.
Specifically, antithyroid drugs work by blocking the absorption of iodine in the stomach. An iodine-rich diet requires higher doses of antithyroid drugs, but higher doses of antithyroid drugs are associated with more side effects, including rashes, hives, and liver disease.
The best food sources of iodine are seafood and seaweed. In addition, iodine is also found in iodized salt and in low levels in eggs, meat and dairy products.
Certain foods can interfere with the absorption of drugs. Therefore, to ensure effective treatment, patients need to strictly follow the instructions, as well as the doctor's nutritional advice when taking any drug.

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References: hopkinsmedicine.org, todaysgeriatricmedicine.com