2. Pharmacodynamic
Most of time,drug produce their effect by
interacting with target biomolecules in the
body,most important of which are
proteins.Proteins on which drug may act can
be grouped into following four categories:-
1.Enzymes.
2.Ion channels.
3.Transporter.
4.Receptor.
4. Ion channel
• ion channels are pore-forming membrane that
allow ions to pass through the channel pore.
Their functions include establishing a resting
membrane potential, shaping actio potentials and
other electrical signals by gating the flow
of ions across the cell membrane, controlling the
flow of ions across secretory and epithelial cells,
and regulating cell volume. Ion channels are
present in the membranes of all excitable cells.
5. Transporter
• Several drug or substrate are translocated
across the membrane by binding to specific
transporet and show their action like:-
• Neuronal reuptake of noradrenaline takes
place by NET.Cocaine and desipramine block
the NET.
• Reuptake of 5-HT takes place byVMAT-2 and
reserpine block the VMATE-2.
6. Receptor
• It is defined as a macromolecule or binding
site present on the surface of cell or inside the
cell that serve to recognise the signal or drug
to show the response.
• They have the property of specificity.
7. Basic terminology
• Affinity:- measure of propensity of a drug to
bind receptor or the attractiveness of drug
and receptor.
• Efficacy:- Potential maximum therapeutic
response that a drug can produce.
• Potency:- Amount of drug needed to produce
an effect.
• Ligand:-Any moecule that bind on recetor
known as ligand.
10. Types of receptor
• Commonly there are two types of receptor:-
• 1.Present on the cell.
• (a)GPCRs.
• (b)Ligand gatted channel.
• 2.Present inside the cell.
• (a)Cytoplasmic receptor.
• (b)Nuclear receptor.
11.
12. GPCRs
• Larger family of cell membrane receptor.
• They are also known as serpentine receptor.
• The molecule has 7 alpha helical structure
containing 3 extracellular loop and 3
intracellular loop.
• Agonist binding site is located on somewhere
between the helix of extracellular face.
• Amine group present on the extracellular face
and COOH are present in the cytoplasmic side.
13.
14. Mechanism of GPCRs
• Gs:-Adenylyl cyclase activation,Calcium
channel opening
• Gi/Go:-Inhibition of adenylyl cyclase,opening
of potassium channel.
• Gq:-Phospholipase-c activation, calcium
channel opening.
15.
16.
17.
18.
19.
20. Ligand gated ion channel receptor
• Ligand-gated ion channels (LICs, LGIC), also commonly
referred to as ionotropic receptors, are a group
of transmembrane ion-channel proteins which open to
allow ions such as Na+, K+, Ca2+, and/or Cl− to pass
through the membrane in response to the binding of a
chemical messenger (i.e. a ligand), such as
a neurotransmitter.
• If these receptors are ligand-gated ion channels, a
resulting conformational change opens the ion
channels, which leads to a flow of ions across the cell
membrane. This, in turn, results in either
a depolarization, for an excitatory receptor response,
or a hyperpolarization, for an inhibitory response.
21.
22. Transmembrane enzyme linked
receptor
• This class of receptor are utilized by peptide
harmone
• It has two types:-
• (1)Enzyme with intrinsic activity.
• Example:-insulin
• (2)Enzyme withought intrinsic activity.
• Example:-Growth
harmone,cytokinin,prolactine
