We generally take medicines after dinner or food because drugs can interact with food that we intake and can affect the drug absorption and make the drug to not achieve its therapeutic value. Therefore, we today blog is about drug and food interactions, basically drug and food interaction are change in drug effect on the body when food and drug is taken together. Not all the food affected by drugs and affected by only certain foods. A drug food interaction can decrease, delay or enhance absorption of a drug. So here I am explaining a research paper in food drug interaction. Many reviews are there for the information of food plays on absorption and bioavailability of drug, from earlier years we get to know the fact that we accept food-drug interactions as a major factor influencing drug absorption, few papers give the information about the food-drug interactions is also related to the size and content of the meal and give us information of time interval between eating and taking medication. It is difficult because there is not a standard meal from with drug interaction can be find out easily, meals can be controlled during a particular drug study, but not in clinical practice. And reported as food exerts its greatest impact on drug absorption when the drug is ingested immediately following the meal. Some of the interaction that food do with the gastrointestinal track are
INFLUENCE OF FOOD ON GI PROCESSES
Drugs are absorbed mainly from the small intestine. Some absorption, particularly that acidic or neutral compounds that may be soluble, may occur efficiently from the stomach. Unique structure of the proximal small intestine and its associated splanchnic circulation (The splanchnic circulation consists of blood supply to gastrointestinal tract, liver, spleen and pancreas) this are the major site by which drugs enter the circulation and from here to liver via portal system and to general circulation. First exposure of drug with metabolizing enzymes of liver at drug concentrations is greater than after it is absorbed subsequently after dilution in circulation. The various ways by which food may affect GI physiology and drug absorption are summarized in table.
SPLANCHIN BLOOD FLOW
Drug molecules cross the epithelial lining of GI tract and can come close of capillary network which is associated with splanchnic circulation (blood flow to the abdominal gastrointestinal organs) the portal circulation joins the systemic circulation at inferior vena cava after through liver. During first pass metabolism the extent of first-pass metabolism is directly related to fraction of drug removed from blood by liver. The greater high-fat and high-protein meals have a lower pharmacokinetics (the branch of pharmacology concerned with the movement of drugs within the body) than a low-fat meal.
Ingestion of food increase the gastric juice and bile and other proteolytic enzyme in the duodenum and proximal small intestine it is thought that increased bile flow may be promote the absorption of lipid-soluble drug (as bile help in emulsification of fat).
Increased secretin of acid into stomach may promote break-up of basic drugs, but may prevent dissolution of acidic drugs. Increased gastric acidity may also affect drug absorption and it is important for enteric-coated products whose absorption may be considerably delayed and possibly reduced in the present of food because of combined effect of slow gastric emptying and increased acid secretion.
Some examples are tetracyclines or penicillamine absorption reduced by chelation (a ligand bonded to central metal atom at two or more points) with heavy metal ions, or by complexation with protein. Food may also act as a physical barrier limit the drug absorptive surface area.
FOOD-DRUG INTEARACTIONS AFFECTING DRUG ABSORPTION
A study says out of 55 drugs 4 were unaffected by food. Some delayed drugs are oral cephalosporins, sulfonamide, aspirin, furosemide and digoxin and their absorption delayed by a heavy fat breakfast but unaffected by a light and lean meal. There is one drug of benzodiazepine derivative midazolam its absorption is delayed and also slightly reduced when taken after meal because of reduced gastric pH resulting in slower absorption of midazolam since the compound exists in a water-soluble ring form at pH<6 and it is inefficiently absorbed.
Some adrenergic beta blocking agents (propranolol, labetalol and metoprolol) is increased in humans when they are taken after meals also show same results
INTERACTIONS CAUSING INCREASED IN DRUG ABSORPTION
Some recent report of food-drug interactions that caused increased drug absorption are in given table. This is good because it increases the therapeutic efficacy, together with possibly reduced GI side-effects. Increased absorption of some substances may cause undesirable systemic side-effects. Two independent studies have shown that chloroquine absorption is increased by food. In a study using rice-based diet and compared to empty stomach. Chloroquine absorption was also increased in healthy volunteers after a high-fat and high-protein meal, but decreased after a low-fat and low-protein meal, compared to fasting state.
SOME RISKY FOODS AND DRUG INTERACRTIONS
1. Calcium-rich food + antibiotics
Daily products such as milk, yogurt and cheese can interfere with certain medication including antibiotics such as tetracycline, doxycycline and ciprofloxacin. These antibiotics may bind to the calcium in milk to form an insoluble substance in the stomach and upper small intestine that the body is unable to absorb.
2. Pickled, cured and fermented food + MAIOs
This food set contains tyramine, which associated with dangerous increase in blood pressure among patients taking monoamine oxidase inhibitors (MAIOs) and certain medication for Parkinson’s disease.
3. Vitamin K-Rich Food + Warfarin
Vitamin K is vital for the production of clotting formation and prevent bleeding anticoagulants like warfarin exert their effect in by inhibiting vitamin K so there can be an antagonistic effect and prevent drug from working.
4. Alcohol + prescription stimulants
Alcohol and stimulant can cause the patient to not fully realize how poisonous this is some interactions are more serious than others.
5.Grapefruits and Grapefruit juice + Statins
Patients should avoid eating grapefruit while taking statins because furanocoumarin chemicals (found in grapefruit) cause an increase in medication potency by interacting with enzyme in small intestine and liver.
CLINICAL IMPLICATION OF FOOD-DURING INTERACTION
food ingestion can influence oral drug absorption to varying degrees, and in an often-unstable manner. The clinical implications of this phenomenon depend on the extent of the interaction and whether circulating drug levels are increased, decreased or delayed. The potential for clinical outcome has been recognized in that drug development programs routinely include at least have one clinical food-drug interaction study. The type of interaction is dependent on a number of factors including the type of drug, type of formulation of drug, drug therapeutic index, type of dose-response curve, and the type and size of meals and time elapsed between eating and taking medication. Most food-drug interactions have been investigated in single-dose studies. As the absorption of most drugs is affected one way or another by food, and as the type of effect is often random, it is recommended that as a general rule drugs should be taken on an empty stomach unless they cause GI soreness or the if the presence of food is necessary in order to achieve desired therapeutic drug levels.
1. Welling, P.G., 1977. Influence of food and diet on gastrointestinal drug absorption: a review. Journal of pharmacokinetics and biopharmaceutics, 5(4), pp.291-334.