Ciii: List the different mechanisms of drug actions with examples
Non Receptor
Mechanism
Chelation
Example
Sugammadex – binds and encapsulates Roc so that it is no longer available for nAChR
Mechanism
Enzyme inhibition/activation
Example
Neostigmine – blocks acetylcholinesterase enzyme so it can no longer break down Ach
Mechanism
Voltage
Example
Lignocaine – inhibits voltage gated Na+ channels
Mechanism
Ionic Interaction
Example
Protamine – positively charged alkaline protamine complexes bind to the negatively charged acidic heparin to form stable complex devoid of any anticoagulant activity
Mechanism
Colligative
Example
Mannitol – alters plasma osmolarity to produce diuresis
Mechanism
Substrate depletion
Example
Capsaicin – subs P depletion of secondary neurons
Mechanism
Unknown
Example
Placebo
Mechanism
Physicochemical
Example
Antacids – alter pH neutralising stomach acid
Receptor
Receptor
G Protein
Example
Coupled to 2nd msg system –
Adr → activates b rec (Gs) → activates AC → ↑cAMP→ ↑phosphorelation → ↑Ca++
Receptor
Enzyme TK
Example
Binding of extracellular receptor leads to activation of intracellular enzyme
Insulin binds 2a+2b → phosphorelation TK → target protein phosphorelation
Receptor
Regulation Gene Transcription
Example
Drug binds cytosol receptor → complex formed moves intracellularly → alters DNA transcription
Eg Thyroxine, Steroids
Receptor
Ligand Gated
Example
Alters Ion Perm – Midaz↑ frequency of
Cl ch opening of GABA Rec to facilitate GABAergic inhibition