by : Eman El-Khateeb Administrator in clinical pharmacy Dep. Tanta University
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Significance ???
1- polytherapy 2- pharmaceutical industry 3- Dosage regimen 4-beneficial ????
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Types of drug interaction
Drug
Drug
Disease food pollutant packaging Pharmaceutical incompatibility
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Drug-Drug interaction Definition: The interaction that Modifies the effect of one drug (object drug) by prior or concomitant administration of another drug (precipitant
drug).
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Precipitant drug: The drug that causes the altered effect of the object drug
Object drug: The drug that its action is altered by the precipitant drug
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Quizz
2min
• Antihypertensive drug+ salt • Hypnotic + Caffeine • Tetracycline + Calcium
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Uni-linear drug interaction Bi-linear drug interaction
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Discuss a drug interaction 1. 2. 3. 4. 5.
Indication of both drugs Mechanism (HOW?) Results/ outcome Evaluation Management & recommendation
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Mechanisms of drug interaction
Pharmacodynamic (PD) •Affects drug action directly
Pharmacokinetic (PK) • Affects plasma conc. with time (ADME) Retrospective VS prospective 11
First: Pharmacodymamic interactions PD Addition Effect
Toxicity
Antagonism Effect
Toxicity 12
Examples •
Additive:
1- Warfarin+ Aspirin(75 mg daily) Additive anticoagulant effect (Effect) 2- Atropin+ T.C.A. Additive anticholinergic side effect (Toxicity) 13
Examples (cont.) • Antagonism 1- CNS depressant+ CNS stimulant (Effect) 2- Gallamine + neostigmine NMRB (Ms relaxant) (Effect)
AchEIs(Ms contraction)
3- Digoxin + potassium (K+) (Antagonizes digoxin toxicity)
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Group excercise
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Group exercise Illustrate the mechanism of drug interaction if present. A- isoprotrenol + propranolol B- Benzodiazepine+ Antihistamine C- Alcohol+ barbiturates D- Aminoglycosides+ cephalosporines E- Gentamycine+ Ethacrynic acid F- Warfarine + vitamine K 16
A-
B-
C-
D-
E-
F17