Faculty of Pharmacy
Department of Pharmacology
5th year Pharmacy Students
Drug-Drug Interaction
Food and Drug Interactions
Food and Drug Interactions
•
the presence of some nutrients in the gastrointestinal tract and/or
in the body’s physiological system, such as in the blood, can
enhance or impair the rate of drug absorption and metabolism.
•
the presence of some drugs can significantly affect the food and
nutrient metabolism and bioavailability in humans.
•
Medications can alter appetite and taste, and also change the
absorption and metabolism of nutrients.
•
This can lead to impaired nutritional status, such as depletion of
some minerals and vitamins from the digestive system, and
sometimes weight problems.
Food and Drug Interactions
Classification:
Drug may affects on of the following:
1- Food intake.
2- weight gain .
3- nutrient Absorption .
4- nutrient metabolism .
5- nutrient excretion .
1-Food Intake
A-Many drugs can cause anorexia, alter taste and smell, cause nausea
and vomiting For example, medications such as methylphenidate
(Ritalin), which influences the central nervous system and so,
reduce appetite.
This medication is often prescribed for hyperactive young children
who are in their rapid growth phase. Long-term use of this drug may
cause growth retardation in these children
B- On the other hand, some drugs are used for weight loss and to treat
obesity by reducing appetite.
-Examples are adrenergic and serotoninergic agents, which cause
satiety, reduce appetite, and increase energy expenditure leading
to weight loss
-Amphetamines are good examples of adrenergic drugs that stimulate
secretion of norepinephrine and reduce food intake
-Serotoninergic drugs, such as fenfluramine and dexfenfluramine,
inhibit the reuptake of serotonin, stimulate satiety, and therefore
reduce food intake
-There are other drugs for treating obesity, such as the appetite
suppressant, sibutramine (also as antidepressant), and orlistat
(lipase inhibitor) which also affect satiety
C- Taste and smell are very important factors that influence food
intake and can subsequently affect the nutritional status of
individuals.
-Taste alteration (dysgeusia or hypogeusia) due to medications is
very common.
-Some hypoglycemic agents such as glipizide, the antimicrobials
amphotericin B, ampicillin, and antiepileptic phenytoin are
among the medications that alter taste perception.
2-Weight Gain
A- Several groups of drugs such as anticonvulsants (caramazepine and
valproic acid), antihistamines (cyproheptadine hydrochloride),
psychotropic drugs (chlordiazepoxide hydrochloride, diazepam) and
corticosteroids (cortisone, prednisone) may increase appetite and
consequently lead to weight gain .
- synthetic derivative of progesterone, medroxyprogesterone acetate
used for the treatment of hormone-sensitive breast and
endometrial cancer, may increase appetite, food intake, and weight
gain.
B-The formulation of drugs in lipid emulsion (e.g., in 10% soybean),
contributes to a significant amount of additional energy
(kilocalories) intake.
C- Other drugs such as lorazepam and morphine may change the
body wt by decreasing the body’s energy expenditure
D-Weight gain could be therapeutically favorable in some cases such as in
cancer and acquired immunodeficiency syndromes (AIDS)-related
cachexia.
Anabolic steroids, such as mandrolone, corticosteroids, cyproheptadine,
hydrazine sulfate, megestrol acetate, dronabinol and oxandrolone, are
prescribed in some cases to promote weight gain
3-Nutrient Absorption
A-Drugs can damage the intestinal absorptive surfaces including villi,
microvilli, brush border enzymes, and the transport system
GI damage can come from over-the-counter drugs such as aspirin and
other acidic drugs, or from antibiotic neomycin or laxatives.
The resulting changes in the mucosal lining interfere with optimum
absorption of nutrients such as iron, calcium, fat (including some
fat-soluble vitamins), protein, sodium, and potassium.
B-Drugs can also influence the absorption of nutrients by changing the GI
transit time or the overall GI chemical environment, likethe pH of the
stomach.
Many laxatives, mineral oil, and cathartic agents reduce transit time in
the GI tract and may cause steatorrhea and loss of fat-soluble
vitamins, A and E, and possibly calcium and potassium
4- Nutrient Metabolism
Some of the important functions of vitamins and several minerals are
their roles as coenzymes/cofactors in metabolic processes in the
human body.
Therefore, certain drugs are targeted to these coenzymes (antivitamins)
in order to reduce the activity of some enzymes in related metabolic
reactions.
Example:
the anticoagulant drug, coumarin, which is a vitamin K antagonist.
Dietary vitamin K can interact with anticoagulant drugs; it also
changes the safety and therapeutic efficacy of these drugs
Therefore, many patients are advised to avoid foods, such as
vegetables, high in vitamin K.
Patient nutrition education is necessary in order to include some
vegetables in their daily diets without changing the efficacy of
these drugs.
5- Nutrient Excretion
Competitive binding and altered reabsorption are the two recognized
mechanisms that may cause drugs to induce nutrient excretion
D-Penicillamine chelates bind with other metals such as zinc,
eliminating it via urine.
Ethylenediaminetetra-acetic acid (EDTA) has been shown to cause
urinary excretion of zinc.
Some diuretics, such as furosemide, ethacrynic acid, and triamterene,
reduce the reabsorption of electrolytes and minerals such as
potassium, magnesium, zinc, and calcium and increase renal
excretion of these elements.