MEAL AND MEDICINE: DOES IT REALLY MATTER WHEN TO TAKE YOUR MEDICINE, BEFORE OR AFTER MEAL?

by Raihah Abdul Rahim, Pharmacist 

Medicine that is administered orally travels down the digestive tract. It will be broken down and absorbed in the stomach or mostly in the small intestine. Once absorbed, it travels to the liver before being transported to its target site via the bloodstream. Since this medicine travels along the same tract as food that we consumed, coadministration of medicine with food may affect the absorption of the medicine. Hence, it is important to know when to take your medicine as some medications should be taken on an empty stomach, some should be taken with food, while others may not be affected by food. Medicine for oral administration is available in many dosage forms such as tablets, capsules, suspensions, solutions, powders, granules, and chewable tablet.

How Food Influences the Efficacy of Medicine?

Gastric Acid Production 
Food stimulates the stomach to produce gastric acid in aiding food digestion. Acidic environment in the stomach affects the bioavailability of medicine for absorption. Medicine with poor acid stability is susceptible to biochemical degradation in acidic environment, hence, it must be taken on empty stomach. Example of medicine with poor acid stability are erythromycin, azithromycin, ampicillin, and phenoxymethylpenicillin. On the other hand, some medicine such as itraconazole and ketoconazole rely on the acidic environment to enhance their absorption, thus they must be taken after food.

Gastric Emptying Rate 
Fatty food will reduce gastric emptying rate which will lead to reduced rate of drug absorption.

Chelation Process 
Chelation is a chemical process in which certain medicines react and bind themselves to the minerals in food such as calcium. This leads to deactivation of the medicine. Thus, such medicines should be taken on empty stomach. Example of such medicines are bisphosphonate and ciprofloxacin.

Bile Secretion 
Food consumption promotes the release of bile salts by the gall bladder. The bile salts enhance the dissolution of lipophilic drug, thus increase drug absorption into systemic circulation. Example of lipophilic drug that should be taken with meals are carbamazepine, tacrolimus, and isotretinoin.

Physical Adsorption 
Certain medicines can easily adsorbed onto the food, thus reducing its bioavailability. For example, digoxin should not be taken with high-fibre foods as digoxin is easily adsorbed on high-fibre foods.

Nausea and vomiting induced by medicine
To reduce the side effects of nausea and vomiting, it is advisable to take these medicines after food. Example: allopurinol, madopar, antidepressants, iron supplements. 

Gastric irritation induced by medicine
Taking medicine that can irritate the stomach after food will reduce this effect. Example: aspirin, non-steroidal anti-inflammatory drugs (NSAIDS), steroids such as prednisolone.

Mechanism of action of the medicine
Antidiabetic medicines such as metformin and gliclazide should be ideally taken with not too long after or before food to avoid hypoglycaemia and to ensure glucose blood level is not too high after food. Antacid should be taken immediately after food as it is used to neutralize the gastric acid produced by the stomach.

Remember! 
Take your medicine before a meal or on empty stomach means taking the medicine at least 30 minutes before food NOT a few minutes before food. If you forget, you can take your medicine at least 2 hours after a meal.