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