In this slides cover all mechanism of drug action,and receptor families.

1. PADMASHREE DR.D.Y.PATIL
COLLEGE OF PHARMACY AKURDI
SUBJECT NAME – ADVANCE PHARMACOLOGY
TOPIC NAME- PHARMACODYNAMIC
GUIDED BY- DR.D.S.SHIRODE
PRESENTED BY – DHANASHRI PRAKASH
SONAVANE

2. • PHARMACODYNAMIC
Pharmaco=Drug
Dynamic=Power
• It covers all the aspects relating to "What a drug does to the body"
Mechanism of action.
• Drug act either by receptor or by non receptor or by targeting specific
genetic changes.
• Mechanism of Action of Drugs
1. Receptor Mediated
2. Non Receptor Mediated

3. A. Non receptor Mediated
(1) By physical action
(a) Osmosis-Mannitol
(b) Adsorption-Activated charcoal for poisoning
(c) Demulcent-Cough syrups
(d) Radioactivity in hyperthyroidism
(2) By chemical action
(a) Antacids- Neutralizing gastric acid
(b) Chelating agent- Dimercaprol (BAL) in arsenic and mercury
poisoning.

4. (3) Through enzymes
(a) Competitive-
Physostigmine and neostigmine completes with acetylcholine for
cholinesterase
(b) Non-Competitive-
Acetazolamide Carbonic anhydrase
(4) Through ion channel - Local anesthetic Block Na+ channel in
neuronal membrane to produce local anesthesia.
(5) Through antibody production Vaccines.
(6) Transporters- Selective serotonin reuptake inhibitor
(SSRI)Antidepressants effect - Bind to 5HT transporter & block
reuptake

5. B. Receptor Mediated
• Receptor are macromolecules, present either on the cell surface,
cytoplasm or in the nucleus with the drug binds and interacts to
produce cellular changes.
• Receptors ore mostly proteins.
• Affinity-Ability to bind to the receptor.
• Intrinsic activity-Ability to produce action after binding.
• If there is no affinity, no intrinsic activity All drug have affinity, but
different intrinsic activity
DRUG RECEPTOR
DRUG
RECEPTOR
COMPLEX Response

6. 1. Based on intrinsic activity:
i. Agonist-Have both affinity and maximal intrinsic activity.
ii. Antagonist-Have affinity but no intrinsic activity
iii. Partial agonist - Have affinity and sub maximal intrinsic activity.
- Produce Submaximal effect but antagonize the action of full
agonist.
i. Inverse agonist-Have affinity but opposite Intrinsic activity.
- Produce an effect in opposite direction to agonist.
i. Non-competitive inhibitors with the same affinity to [E] and [E-
S] -the inhibitor binds at the allosteric site independently of
substrate binding
ii. Competitive inhibitors-which have bind to same receptor site and
progressively inhibit the agonist response.
-but not intrinsic activity.

7. Receptor Families’
1. LIGAND-GATED ION CHANNEL (INOTROPIC
RECEPTOR):
• This drug binds directly to the receptor located on an ion channel
without mediated by G-Protein.
• Wherever drugs bind the channels open and ions can enter.
• This type of receptor are fastest acting receptor.
• Binding of drug to inotropic receptor  Opens the ion channel-
(Na, K,Ca,CI) Flow of ions through channel Hyperpolarization
/Depolarization Tissue response.

9. 2. G-Protein Coupled Receptor
• It also known as heptahelical/serpentine receptor.
• It is largest family of cell membrane receptor.
• G protein are membrane protein and have 3 sub units alpha ,beta
,gamma heterotrimer.
• When all are join together G-protein coupled receptor is
inactive.GPCRs control cell function via Adenyl cyclase,
Phospholipase c and ion channel when drug binds to the receptor
which is turns activates a g protein that may result in activation or
inhibition of---
I. Adenyl cyclase
II. Phospholipase c
III. Ion channel
• This act on Gs,Gi,Gq receptors.

11. 3. Enzymatic Receptor
• Enzymes are Stimulated at outer end.
The drug binds to the extracellular
sites. The intracellular sites has
enzymatic activity.
• Ex: Prolactin, insuline, Growth
Harmone,Cytokinine
(Interleukine,Interferon,TGF
Transforming Growth Factor ).

12. 4. Nuclear Receptor
• This type of receptor is slowest acting receptor.
• Only lipid soluble drug can also act on it.
• If the drug bind to nuclear receptor, then they bind with DNA and act on
translation, transcription, replication and these process become slower.
• Both type of receptor finally act on nuclear mechanism by affecting
transcription.
• Two type of nuclear receptor
i. Cytoplasmic receptor: Glucocorticoids, Mineralocorticoids, Progestin
ii. Nuclear Receptor:T3,T4,Vitamin A,D ,Estrogen.

14. Jak-Stat Binding Receptors
• The Jak-Stat (Janus Kinase-Signal transducer and activator of
transcription) signaling pathway transmits information from
chemical signals outside the cell which cause DNA transcription
• Contain 3 main Components:
I. Receptor
II. JAK-Janus Kinase
III. STAT- Signal transducer and activator of transcription.

16. Neurotransmitter and their receptors

17. Combination Effect of Drug
• Synergism
An interaction between two or more drugs that causes the total effect of
the drugs to be greater than the sum of the individual effects of each
drug.
• Antagonism
antagonism occurs when a drug binds to a different receptor and
produces a physiological response that opposes the effect of the agonist-
bound receptor.