Drug Drug Interactions
 | |  | |  | |  | |  | |  |
Drug –Drug interaction:
Drug-Drug Interaction Mechanisms
A. Pharmacokinetic Mechanisms
1. Absorption
a) Drug binding in the GI tract
b) GI motility alterations
c) GI pH alterations
d) Intestinal flora alterations
e) Drug metabolism alterations within the wall of the intestine
f) Complexation and adsorption
2. Protein –binding displacement
3. Modified renal excretion
4. Modified nonrenal excretion
4. Cytochrome P-450
5. P-450 Enzyme induction
6. P-450 Enzyme inhibition
B. Pharmacodynamic Mechanism
1. Antagonistic effects
2. Synergistic side effects
3. Indirect pharmacodynamic effects
A. Pharmacokinetic Mechanisms
1. Absorption
a) Drug binding in the GI tract
b) GI motility alterations
c) GI pH alterations
d) Intestinal flora alterations
e) Drug metabolism alterations within the wall of the intestine
f) Complexation and adsorption
2. Protein –binding displacement
3. Modified renal excretion
4. Modified nonrenal excretion
4. Cytochrome P-450
5. P-450 Enzyme induction
6. P-450 Enzyme inhibition
B. Pharmacodynamic Mechanism
1. Antagonistic effects
2. Synergistic side effects
3. Indirect pharmacodynamic effects
Conversely, drugs can interact via a pharmacodynamic mechanism. The detection of pharmacodynamic interactions
requires knowledge of the pharmacology of the drugs involved. For example, drugs can interact by producing
antagonistic effects on each other. That would be considered a pharmacodynamic interaction. Additionally, drugs
can interact by causing synergistic adverse effects or by producing indirect pharmacodynamic effects.