B pharmacy 6 semester 2013

1. Pune District Education Association
Shankarrao Ursal College Of Pharmaceutical
Science & Research Center ,Kharadi Pune 14
Seminar on
MECHANISM OF DRUG INTERACTION
By :
Ms. Tejal Kale (Roll no.31)
Date : 19/3/2024
Third Year B Pharm (Sem IV)
Guided By :
Dr.R.Y.Patil
Academic Year : 2023-2024

2. Mechanism of Drug Interaction
The three mechanisms by which an interaction can develop
are –
1. Pharmaceutical interactions
2. Pharmacokinetic interactions
3. Pharmacodynamic interactions

3. ● Pharmaceutical Interactions
● • During dosage form preparation or at time of administration
● • Dissolving the drug in solvent
● • Mixing drugs in powder , solution or injection forms
● Pharmacokinetic Interactions
● • Absorption (Complex or Chelate formation, Altered stomach pH
● ,Ionization ,GIT motility ,First Pass Metabolism)
● • Distribution (Protein binding)
● • Metabolism (Enzyme induction/inhibition)
● • Excretion (Altered pH , Ionization ,Enteri-hepatic recirculation)
● Pharmacodynamic Interactions
● • At receptor or tissue level

4. 1. Pharmaceutical Interaction
● These are also called as pharmaceutical
incompatibility. It is a physicochemical
interaction that occurs when drugs are
mixed in intravenous (i.v).Infusion
causing precipitation or inactivation of
active principles
● Example-
Ampicillin , Chlorpromazine and
Barbituates interact with dextran in solutions
and are broken down or from chemical
compounds

6. "These interactions are those in which ADME properties of the
object drug is altered by the precipitant and hence such
interactions are also called as ADME interactions".
The resultant effect is altered plasma concentration of the
object drug.
Drug act remotely from target site to alter plasma
concentration
2. Pharmacokinetics Interaction

7. Absorption Interactions
• Are those where the absorption of the object drug is altered
• The net effect of such an interaction is
> Faster or slower drug absorption
> More or less complete drug absorption
Major mechanisms of absorption interactions are :
1. Complexation and absorption
2. Alteration in GI pH
3. Alteration in gut motility
4. Inihitbion of GI enzymes
5. Alteration of GI micro flora
6. Malabsorption syndrome

8. DISTRIBUTION INTERACTION
• Are those where the distribution pattern of the object drug is altered
• The Major mechanism for distribution interaction is alteration
in protein-drug binding
• Displacement of plasma protein binding
8

9. METABOLISM INTERACTION
• Are those where the metabolism of the object drug is altered
• Mechanism of metabolism interaction include
 Enzyme induction - Increased rate of metabolism
 Enzyme inhibition - Decreased rate of metabolism
• It is most significant interaction in comparison to other
interactions and can be fatal

10. ELIMINATION INTERACTION
Are those where the excretion pattern of the object drug is altered
• Major mechanism of excretion interaction are
>Alteration of renal blood flow
>Alteration of urine Ph
>Compitition for active secretion
>Forced diuresis
Mostly in case of drugs actively secreted by tubular transport mechanism

11. 3. Pharmacodynamic Interactions
•These interactions are derived from the modification of the action of one drug at the target site
by another drug , independent of a change in it's concentration.
• Are those in which the activity of object drug at it's site of action is altered by the precipitant
• Such interactions are of two types
1. Direct pharmacodynamic interactions
2. Indirect pharmacodynamic interactions

12. 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

13. Antagonism
• The interacting drugs have opposing action
• Example: Acetylcholine and noradrenalin have opposing effect on heart rate
Addition or Summation
• The interacting drugs have similar action and the resultant effect is the sum of the individual
drug responses
• Example: CNS depressants like sedatives and hypnotics
Synergism or Potentiation
• It is and enhancement of action of one drug by another drug
• Example: Alcohol enhances the anaglesics activity of aspirin

14. Indirect Pharmacodynamic Interactions
• In which the both the object and the precipitant drugs have unrelated effects
• But later in some way alerts the effects of the former
• Examples: Salicylates decrease the ability of the platelets to aggregate thus impairng the
Homeostasis if warfarin induced bleeding occurs

15. Drug interactions by Dr Sunisha Kulkarni , SOS in pharmaceutical sciences ,Jiwaji University,
Gwalior .
https://www.slideshare.net/SreenivasareddyThalla/drug-interactions-245626816
Herbal Drugs Technology ,by Dr V.M.Shinde and Mrs.K.S.Bodas-Yadav ,unit 5
https://www.slideshare.net/FarazaJaved/drugs-interactionsppt
Herbal drug interactions - an overview by ranjeet kumar bhargav and rehana Praveen ,BBS institute
of pharmaceutical and allied sciences, Noida.
https://www.ncbi.nlm.nih.com
BMC pharmacology and toxicology ,by EM Dagnew ,2022 Cited by 7 drug drug interactions
References

16. THANK YOU !!