Drug-food and drug-herb interactions can occur via several mechanisms: 1) Reduced or delayed drug absorption due to food components binding to drugs or slowing gastric emptying. Examples include calcium in milk binding tetracycline and tannins in tea impairing iron absorption. 2) Increased drug absorption when foods increase drug dissolution, secretion of gastrointestinal fluids, or delay gastric emptying. Examples include increased absorption of antibiotics with fatty foods. 3) Altered drug metabolism through effects on cytochrome P450 enzyme activity. Grapefruit juice and St. John's Wort inhibit CYP3A4, increasing drug levels of medications metabolized by this enzyme and risk of toxicity. 4) Changed

1. INTER
Presented to you by: Kinda Sharrouf & Qussay Abbas
Drug
FOOD
Supervised by : Dr . Shadi Homsi

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 A drug interaction: is a situation in which a substance affects
the activity of a drug when both are administered together i.e.
the effects are increased or decreased, or they produce a new
effect that neither produces on its own.
 Typically, interactions between drugs come to mind (drug-
drug interaction). However, interactions may also exist
between drugs and foods (drug-food interactions), as well
as drugs and medicinal plants or herbs (drug-plant
interactions).

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In contrast to the easy access to
information on drug-drug
interactions, the information
about food-drug interaction is not
always available conveniently. It is
a difficult and complex problem
to accurately determine the effects
of food and nutrients on a
particular drug

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02
Drug/Nutrient
interactions
01
Food/Drug
Interactions
04 Antagonism
03Synergy

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The factors or conditions that predispose or favour the appearance of interactions include:

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EXCRETION
METABOLISM
DISTRIBUTION
ABSORPTION

9. 1- Reduced or delayed drug absorption in the presence of food:
The presence of food may decrease or delay drug absorption and that could be due
to:
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The formation of insoluble complexes
Delayed gastric emptying
Increased viscosity due to the
presence of food

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1- Reduced or delayed drug absorption in the presence of food:
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The calcium in the milk binds to the antibiotic like
tetracycline and ciprofloxacin due to their chelation property
that lead to insoluble complex that prevents gut absorption
Tannin present in tea may impair iron absorption
Insoluble dietary fiber, the kind found in bran or brown rice,
can seriously inhibit body's absorption of the heart
medication digoxin

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1- Reduced or delayed drug absorption in the presence of food:
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If an orally administered drug harms the stomach lining
or decomposes in the acidic environment of the
stomach
For these coatings to dissolve, they must come in contact with the less
acidic environment of the small intestine or with the digestive
enzymes there
A tablet or capsule of the drug can be coated with a substance
intended to prevent it from dissolving until it reaches the small
intestine
One example is aspirin, when food delays gastric emptying this delays aspirin
absorption

12. Accumulated evidence suggest that:
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1- Increased drug absorption in the presence of food:
More complete drug
dissolution
Food induced
gastrointestinal secretions
Delayed gastric emptying
Increased drug
absorption

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1- Increased drug absorption in the presence of food:
Bioavailability of Axetil
(Ceftin), an antibiotic,
is 52% after a meal and
37% in the fasting state
Poorly water soluble
drugs (griseofulvin and
mebendazole), may not
enter solution readily
in the stomach.
Administration of such
drugs with very fatty
foods can increase
bioavailability

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 Most drugs are chemically altered within Liver to less toxic and less
lipid-soluble metabolites.
 CYP450 most important isoenzymes responsible for liver metabolism.
 CYP 3A4
 CYP 2D6
 CYP 2C8

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Types of drug metabolism interaction :

16. •Increased blood concentration
of drug
•Decreased blood concentration
of drug
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Alteration in activities of enzymes that metabolize drugs can
result in:

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LIQUORICE
GRAPEFRUIT JUICE

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 Inhibits the cytochrome P-450 3A4 enzyme.
 (calcium channel blockers, HMG CoA
inhibitors, anti-anxiety agents)
 Effect persists for 72 hours so it is not helpful
to separate the drug and the grapefruit

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 Anti-hypertensives (nifedipine)
 Immunosuppressants (cyclosporine)
 Antihistamines (astemizole)
 Protease inhibitors (saquinavir)
 Lipid-Lowering Drugs (atorvastatin, lovastatin,
simvastatin)
 Anti-anxiety, anti-depressants (diazepam,
triazolam)

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Grapefruit juice and statin drugs
Too much of the drug may stay in
the body
increasing risk for:
liver damage
muscle breakdown
kidney failure.

24. LIQUORICE
 Liquorice contain glycyrrhizin (glycyrrhizinic or
glycyrrhizic acid)
 Glycyrrhizinic acid is hydrolyzed in the intestine to
pharmacologically active compound glycyrrhetic
acid which inhibit 11 betahydroxysteroid
dehydrogenase.
 This increase cortisol in kidney and act as
aldosterone (fluid retention, hypokalemia,
hypertension)
 Ex:
diuretics and antihypertensive

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St John's wort is a flowering plant, it has been
used for a variety of conditions, including
kidney and lung ailments and to aid wound
healing. Now it is a medicinal herb with
antidepressant activity and potent anti-
inflammatory properties.

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cytochrome
P450
P-
glycoprotein
Serotonin

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CYP3A4: the main clinically relevant effect of St John’s wort on cytochrome P450 is the
induction of CYP3A4. This has been shown to be related to the constituent, hyperforin
and may also induces CYP2C19, CYP2C9, CYP2C8, CYP2E1, CYP1A2 and CYP2D6.
St John’s wort cause a reduction
in the anticoagulant effects of
warfarin
Mechanism:
It is suggested that the St
John’s wort increases the
metabolism and clearance of
the anticoagulants possibly by
induction of cytochrome P450
isoenzyme CYP3A4
St John’s wort modestly decreases
the AUC of gliclazide
Mechanism:
Gliclazide is a substrate of the
cytochrome P450 isoenzyme
CYP2C9 and St. John’s wort
induces this isoenzyme,
thereby increasing the
metabolism of gliclazide and
reducing its levels

28. St John’s wort is known to affect P-glycoprotein activity, especially intestinal P-
glycoprotein:
it is a potent and long-acting induction,that leads to the clinically relevant drug
interactions of St John’s wort that occur as a result of this mechanism.
Hyperforin is implicated as the main constituent responsible for the effect.
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There is good evidence that some preparations of St John’s wort can
reduce the levels of digoxin by about one-quarter to one-third.
Mechanism:
St John’s wort, and specifically hyperforin has been shown to
increase the activity of the P-glycoprotein drug transporter protein
in the intestines, which reduces the absorption of digoxin

29. St John’s wort inhibits the reuptake of 5-hydroxytryptamine (5-HT, serotonin) and this
has resulted in a pharmacodynamic interaction, namely the development of serotonin
syndrome with conventional drugs that also have serotonergic properties.
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St John’s wort interaction with SSRIs:
Cases of severe mania and
serotonin syndrome have
been reported in patients
taking St John’s wort with
SSRIs.
Mechanism:
A pharmacodynamics
interaction may occur
between St John’s wort
and SSRIs because they can
both inhibit the reuptake
of 5-hydroxytryptamine
(serotonin).

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Mechanisms :
o Alter drug reabsorption in
the kidneys
o Cause an increase or
decrease in urinary losses
o Altered urine PH.

31. Results :
o Inadequate excretion of
medications can cause
toxicity
o Excessive losses of
medications can reduce
the therapeutic effect
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32.  Cranberry juice will alter pH
and cause higher dissolution.
 This occurs with sulfonamides

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34. 35Warfarin

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Garlic can cause additive antiplatelet effect in
combination with warfarin, heparin, and low
molecular weight heparin (LMWH), and
cause increased risk of bleeding.

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 Caffeine has additive effects on theophylline
 Causing nervousness, tremor, insomnia
 It has been reported that caffeine increased
serum theophylline levels by 20%–30% and
increased the half-life of theophylline by
decreasing clearance.

37. One of the classic examples is that of the monoamine oxidase inhibitor (MAOI) drug
class and the amino acid tyramine that is contained in aged cheeses, pickled/smoked
meats, red wine and fermented foods.
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1
• Tyramine is an indirect sympathomimetic amine that releases norepinephrine
from the adrenergic neurons, causing a significant pressor response.
2
• Typically, tyramine is metabolized by the enzyme monoamine
oxidase before any significant increases in blood pressure are seen.
3
• If the enzyme is blocked, however, severe and potentially fatal rises
in blood pressure can occur when tyramine-rich foods are ingested.

38. Some drugs can have an effect on a patient’s nutritional status.
The mechanisms for these effects are varied and are usually due to
drug side effects. A drug can enhance or inhibit nutrient
bioavailability. Thus, it affects the nutritional status of individuals
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39. • The using of chemotherapeutic agents to treat cancer can affect growing tissues,
particularly the lining of the gastrointestinal tract (GIT). Nausea is a common
side effect and can interfere with eating. Some patients can have oral and
esophageal lesions and it can cause pain upon chewing and swallowing
(odynophagia).
• Antacids change the pH of the stomach and cause chelating with some minerals,
consequently reducing their absorption. Higher pH in the stomach reduces the
absorption of iron, calcium, zinc, and magnesium.
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• Vitamin folate (B6) is a cofactor for the enzyme dihydrofolate reductase, it is
necessary for nucleic acid biosynthesis and cell replication. This vitamin will be
excreted because the drugs displace it from dihydrofolate reductase to reduce cell
replication, like methotrexate (MTX) for treating leukemia and rheumatoid arthritis
• Many laxatives 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
• Some diuretics, such as furosemide reduce the reabsorption of electrolytes and
minerals such as calcium, magnesium, zinc, and increase renal excretion of these
elements

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Time-related

43. Acts as gastric irritant; in combination
with other irritants such as NSAIDs may
increase chance of GI bleed
Should not be combined with other
hepatotoxic drugs such as acetaminophen,
methotrexate
Can inhibit gluconeogenesis when
consumed in a fasting state; can prolong
hypoglycemic episode caused by insulin or
other diabetes meds

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Pharmacodynamic alcohol-medication interactions
• occurs most commonly in the central nervous system (CNS).
• With some medications (e.g., barbiturates and sedative medications called benzodiazepines),
alcohol acts on the same molecules inside or on the surface of the cell as does the medication.
Alcohol-medication interactions fall into two
general categories:
pharmacokinetic and pharmacodynamic

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Pharmacokinetic interactions
The metabolism of the affected medications is
accelerated, because alcohol enhances the activity of
medication-metabolizing cytochromes. When alcohol is
not present simultaneously to compete for the
cytochromes, increased cytochrome activity results in an
increased elimination rate for medications that these
enzymes metabolize.

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 Read directions, warnings and interaction precautions printed on all
medication labels and package inserts.
 Do not stir medication into your food or take capsules apart.
 Do not take vitamin pills at the same time you take medication.
 Do not mix medication into hot drinks because the heat from the drink
may destroy the effectiveness of the drug.
 Never take medication with alcoholic drinks.
 Be sure to tell your physician about all medications you are taking, both
prescription and nonprescription.

48. Thank You!
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