Drug drug inter-action of pulmonary concern

1. By
Mahmoud E. Abou El-Magd
DRUG-DRUG INTER-
ACTION OF PULMONARY
CONCERN

2. INTRODUCTION
DRUG - DRUG INTERACTIONS 2
• An interaction occurs when the effects of one drug are changed
by another drug, food, drink or exposure to an environmental
chemical.
• A drug interaction occurs when two or more drugs interact in
such a way that the effectiveness or toxicity of one or more of
the drugs is altered.
• Interactions can be harmful, either by increasing the toxicity of a
drug or by reducing its efficacy. However, some drug
interactions can also be beneficial .

3. RISK FACTORS
• Genetic make up .
• Multiple prescribers .
• Multiple pharmacies .
• Specific population like e.g, females , elderly, obese, criticaly ill
patient , trasplant recipient .
• Specific illness E.g. Hepatic disease, Renal dysfunction .
• Narrow therapeutic index drugs as warfarin , digoxin ,
theophyllin .
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4. OUTCOMES OF DRUG INTERACTIONS
1) Loss of therapeutic effect .
2) Toxicity .
3) Beneficial effects e.g additive & potentiation (intended) or
antagonism (unintended).
4) Chemical or physical interaction e.g I.V incompatibility in
fluid or syringes mixture .
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5. DRUG - DRUG INTERACTIONS 5

6. DRUG - DRUG INTERACTIONS 6
Mechanisms

7. TYPES OF PHARMACOKINETIC INTERACTION.
DRUG - DRUG INTERACTIONS 7

8. ALTERED GIT ABSORPTION.
•Altered pH
•Altered bacterial flora
• formation of drug chelates or complexes
• drug induced mucosal damage
• altered GIT motility.
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9. TYPES OF PHARMACOKINETIC INTERACTION.
DRUG - DRUG INTERACTIONS 9

10. CYP450 ISOENZYMES
DRUG - DRUG INTERACTIONS
10
• Present in lipid layer of the endoplasmic reticulum of
hepatocytes .
• Major enzymes involved in metabolism and bioactivation .
• About 75% of reactions .

11. CYTOCHROME P450 (CYP450)
DRUG - DRUG INTERACTIONS 11
• Inducer
• Speeds up metabolism
• Decreases substrate level (lack of efficacy is concern)
• Gradual onset/offset
• Inhibitor
• Slows metabolism
• Increases substrate level (toxicity is concern)
• Quick onset/offset

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14. It means alteration of the dug action without change in its
serum concentration by pharmacokinetic factors.
These are of two types
1.direct pharmacodynamic interactions.
2.Indirect pharmacodynamic interactions
PHARMACODYNEMIC INTERACTION
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15. DIRECT PHARMACODYNAMIC INTERACTIONS:
In which drugs having similar or opposing pharmacological effects are
used concurrently.
The three consequences of direct interactions are
1.Antagonism.
2.Addition or summation.
3.Synergism or potentiation.
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16. INDIRECT PHARMACODYNAMIC INTERACTION:
In which both the object and the precipitant drugs have unrelated
effects.but the latter in Some way alerts the effects of the former.
Example: salicylatesdecrease the ability of the platelets to aggregate
thus impairing the Homeostasis if warfarin indused bleeding occurs.
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17. PHARMACEUTICAL INTERACTIONS
Also called as incompatibility.it is a physicochemical interaction that
occous when drugs are mixed in i.v . Infusions causing precipitation
or inactivation of active principles .
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18. DRUG - DRUG INTERACTIONS 18
Examples

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26. MISCELLANEOUS ANTIBACTERIAL
ANTIBIOTICS
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27. ANTIMYCOBACTERIAL AGENTS
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29. ANTICOAGULANTS/THROMBOLYTIC
AGENTS
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33. ANTICONVULSANTS
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34. ANTINEOPLASTIC AGENTS
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35. BRONCHODILATORS
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38. CORTICOSTEROIDS
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45. FOOD-DRUG INTERACTIONS…
DRUG - DRUG INTERACTIONS 45
• -Advise patients to take medication with a full glass of
water.
• -Do not take vitamin pills at the same time you take
medication (i.e, take medication 1 hour after taking
vitamins).
• -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.

46. INFLUENCE OF FOOD ON DRUG INTERACTION:
 Food effects the rate and extent of absorption of drugs from the
GI tract.
Example: Many anti biotics should be given atleast 1hr before or 2hr
after meals to achieve Optimal absorption.
 Diet also may influence urinary pH values.
Lime juice is most acidic
Milk products alter pH
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47. DRUG INDUCED NUTRITIONAL EFICIENCIES
DRUG AFFECTED NUTRIENTS POSSIBLE MECHANISM EFFECT
ANTIEPILECTIC DRUGS
(phenytion ,
phenobarbitone, primidone,
valproic acid)
Folate
Vitamin D
Vitamin E
Zinc
Selenium
Vitamin K
Decreased absorption
Enzyme induction
Excess utilization ?
Chelation
Peroxide damage
?
Megaloblastic anemia
Osteomalacia
Haemolysis
Anorexia , celebellar
dysfunction
Hepatotoxicity
Hemorrhage
ANTIFOLATE DRUGS
(e.g. methotrexate,
pyrimethamine,
trimethamine, trimethoprim)
Folate Dihydrofolate reductase
inhibition
Megaloblastic anemia,
cytopenia
CEPHALOSPORINS
(Cefamendole,
cefoperazone, latamoxef)
Vitamin K Decreased prothrombin
synthesis
Bleeding episodes
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48. DRUG AFFECTED
NUTRIENTS
POSSIBLE
MECHANISM
EFFECT
CORTICOSTEROIDS Calcium Decreased Ca, vitamin D
metabolism
Bone disorders
COUMARIN
ANTICOGULANTS
Vitamin K ? Hemorrhage
DIURETICS Zn , Ca, K, Mg Urinary loss depression Weakness , electrolyte
imbalance
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DRUG AFFECTED
NUTRIENTS
POSSIBLE
MECHANISM
EFFECT
ISONIAZED (INH) Pyridoxine Complex formation Peripheral neuropathy,
Convulsions, psychatric
manifestation

49. DRUG AFFECTED
NUTRIENTS
POSSIBLE
MECHANISM
EFFECT
PARA – AMINO
SALICYCLIC (PAS)
Vitamin B12 decreased absorption Megaloblastic anaemia
POTASSIUM CHLORIDE Vitamin B12 decreased ileal Ph Decreased absorption
RIFAMPCIN Vitamin D Enzyme induction Osteomalacia
SALICYLATES Vitamin C, Folate Increased excretion,
decreased uptake
Anemia ,infection
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51. INFLUENCE OF SMOKING ON DRUG
INTERACTIONS ?!!
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52. INFLUENCE OF ALCOHOL ON DRUG
INTERACTION ?!!
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