Dose of drug administered
ABSORPTION

DISTRIBUTION

Drug in tissues

Drug in systemic circulation

Pharmacokinetics
Drug metabolized or excreted
ELIMINATION

Drug at site of action

Pharmacologic effect Pharmacodynamics Toxicity Efficacy

PHARMACOLOGY Pharmacodynamics
Actions of drug on the body  Specific to a drug/ class of drugs • Interaction with target sites (receptors/enzymes) • Effects at site of action • Dose-response relationship • Reduction in symptoms • Modification of disease process • Unwanted/side effects • Drug interactions • Inter- and intra-patient differences

Pharmacokinetics
Actions of body on the drug  Non-specific, general processes • Absorption from site of administration • Distribution to the
Rested


 Non-conducting

 Closed but openable in reponse

to appropriate stimulus

Activated (open) 3. Inactivated
2.

 Closed and unable to open in

response to appropriate stimulus for rested state channel



When ligand binds to the ligand-binding site  Conformation change in other parts of ROC molecule  Opening of central, ion-selective pore  Increase transmembrane conductance  Alters electrical potential across the membrane  Transmits signal across plasma membrane



Acetylcholine binds to the nicotinic acetylcholine receptor
 Opening of ion channel  Allows Na+ to flow down its

concentration gradient into cells  Produce a localised excitatory postsynaptic potential (a depolarization)

Similar to ROC  But operated by voltage, instead of ligands  Examples:


Cardiac Na+ channel Ca2+ selective VOC K+ selective VOC



Cellular response occur in the range of milliseconds after binding of agonist to a ligand-gated channel

(4) G-Protein Coupled Receptor

Receptor located on cell membrane  G protein


› A complex of 3

subunits (α, β and γ) › A transduction component › Energy dependent (ATP, GDP)



In the rested state (When no ligand is present)
G protein o Subunits are bound together o GDP (Guanine nucleotide diphosphate) is tightly bound to the α subunit of the G protein

G protein in this