Food Drugs interactions

 By Sarafina Msigwa and Telesphory Wamara

Ever wondered why you are instructed to take or not to take a certain food while you are on a certain medication dosage?. Food has either positive or negative effects on bioavailability of a drug, on the other hand drugs also affect the way body utilizes food. Some interactions are common or well known by people while others are not, It is important to know how these interactions occur. On this writing you are also going to see interactions of drugs with beverages and dietary supplements 

While these interactions may have an advantage but in most cases they result into adverse drug reactions making it very important for physicians to provide correct and full information to the patients who should also adhere to the instructions.

1.      GRAPE FRUIT JUICE (GFJ)

The grape fruit juice is one among fruit juices having interaction with almost all types of drugs. Its main effects results from its ability to change metabolism of medications by the body and also its effect on liver ability.

GFJ contains furanocoumarins that inhibits CYP3A4 enzymes present on the intestines as a result there is accumulation of medications such as cyclosporine, felodipine, midazolam to toxic levels

Patients taking anticonvulsants are advised not to take GFJ within 1-2 hrs of taking the medication

GFJ also contains compounds that are esterase inhibitors mediating pharmacokinetic drug interaction with most Ca2+ channel antagonists eg. enalapril and statins eg. Lovastatin1.     

2.  WARFARIN

Vegetables such as broccoli, Spinach have high amount of Vit K. So when a patient take these types of food while he/she is on warfarin therapy may interfere the effectiveness and safety of warfarin, vitamin k antagonises the effect of warfarin

3.      TYRAMINE CONTAINING FOODS

These includes matured cheese, red vine, ripped bananas, yoghurt, shrimp paste. The patient that is on Antidepressants specifically Monoamine oxidase inhibitors eg. Phenelzine, isocarboxazid is on a high risk of getting hypertensive crisis because tyramine is usually degraded by Monoamine oxidase so in presence of those inhibitors it escapes the degradation and reaches systemic circulation to stimulate adrenergic neurons

4.      ANTIHYPERTENSIVE DRUGS

When propranolol is taken with food rich in protein it may result into increased serum levels of the medication, Smoking decreases its plasma levels by increasing its metabolism

The absorption of ACEs inhibitors such as captopril, enalapril increases when the stomach is empty

Liquorice extract containing glycyrrhizin and glycyrrhetinic is a potential inhibitor of 11-bet-hydroxyl steroid dehydrogenase increases cortisol levels causing sodium retention and potassium depletion, oedema, increased blood pressure.

5.      ANTIBIOTICS

Co-administration of some antibiotics with milk products (source of divalent ions such as calcium and magnesium) causes complex formation that can not be absorbed . Fluoroquionolones (ciprofloxacin, levofloxacin, ofloxacin), tetracycline are among the medications that are affected by that interaction

GFJ also affects the absorption of ciprofloxacin, so the concomitant ingestion should be avoided

Tetracycline and Azithromycin should be taken 1 hour before or 2 hours after meals to avoid effect of food on its bioavailability

6.      ANALGESICS & ANTIPYRETICS

Acetaminophen should be taken on an empty stomach because food affects its absorption and onset of action, NSAIDs such as ketoprofen, naproxen, ibuprofen should be taken with food because they causes stomach irritation.

Research shows an increase of extent of absorption when ibuprofen was taken with Coca-Cola, so the patient should avoid taking it with the medication or reduce the dose when they are taken together whereas the former is easier to practice for assurance of safety.

Alcohol should be avoided when taking NSAIDs because it can increase the chance of liver damage and stomach bleeding.

7. 7   BRONCHODILATORS

The effects of food on medications of this group varies, Theophylline concentration increases in the body when taken with high fat meals and decreases when taken with food rich in carbohydrate

Foods or drinks reach in beverages containing caffeine eg chocolates, colas, coffee and tea should be avoided by the patient taking theophylline this is because theophylline is a xanthine derivatives and these substances contains xanthine so it is expected that drug toxicity will occur and also over stimulation of the central nervous system. GFJ increases the oral bioavailability of theophylline

8   ANTIHISTAMINES

Antihistamines includes loratadine, fexofenadine, cimetidine, cetirizine. These medications are advised to be taken on an empty stomach to increase their bioavailability.

9.     ANTITUBERCULAR DRUGS

High fat meals decreases the serum concentration of cycloserine that results into incomplete bacteriostatic activity .Isoniazid inhibits Monoamine oxidase so it should also be avoided with tyramine rich foods (reason is as explained in point no 3)

10.      ANTIDIABETICS

Immediate release glipizide should be taken 30 minutes before meals while the extended release one should be taken with breakfast. Acarbose should be taken immediately at the start of each meal because it delays carbohydrate absorption by inhibiting an enzyme alpha glucosidase


11.      ANTITUMOR DRUGS

    Cow’s milk should be avoided to be taken concurrently with Mercaptopurine a drug used in Acute Lymphoblastic anemia and Chronic Mylegenous leukemia, this is because cow’s milk contains high amount of xanthine oxidase (an enzyme which inactivates mercaptopurine). The best way to avoid this is by allowing atleast two hours to pass after taking the drug before taking the cow’s milk.

    Tamoxifen should not be taken with sesame seeds as studies shows that the seeds interferes the tumor regression activity of Tamoxifen

               TAKING DRUG WITH OR WITHOUT FOOD

  It is well known that food may interact with the drug either pharmacokinetically ( absorption, distribution, metabolism, elimination) or pharmacodynamically

The table below shows drugs, their dietary recommendations and the possible mechanisms of action


DRUG

DIETARY RECOMMENDATIONS

POSSIBLE MOA

Aleandroanic acid

Without food or milk

Chelation

Albendazole

With a fatty meal

Increased solubility

Ampicillin

Without food

Acid lability

Azithromycin Capsule

Without food

Acid lability

Captopril

Without food

Decreased absorption

Carbamazepine tablets

With consistent relationship to meals

Absorption is favored by bile secretion

Cefuroxime

With meal

Depends on gastric acid for solubility

Ciprofloxacin

Without milk

Chelation

Digoxin

With consistent dietary fibre intake

Binding to fibre

Doxycycline

Without milk

Chelation

Erythromycin stearate

Without food

Acid lability

Erythromycin enteric coated

Without food

Acid lability

Furosemide

Without food

Reduced intestinal absorption

Griseofulvin

With a fatty meal

Absorption is favored by bile secretion

Isoniazid

Without food

Acid liability

Itraconazole Capsules

With meals

Depends on gastric acid for solubility

Itraconazole Solution

Without food

Food increases first pass metabolism

Levodopa

Without food

Competition with food components

MAO Inhibitors eg, Phenelzine

Without tyramine rich foods such as cheese

Blocked tyramine degradation

Penicillamine

Without food or milk

Chelation

Spironolactone

Without foods rich in potassium

Pharmacodynamic interaction

Warfarin

Without foods rich in Vitamin K

Direct antagonism by Vitamin K

 


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