2003B06 List the potential clinical uses of an alpha-2 adrenoceptor agonist
and outline the limitations of clonidine for each.

 

Uses:

CNS

·  Adjunct to anaesthesia

·  Sedation

·  Anxiolysis

·  Premedication

·  Analgesia

CVS

·  ↓BP

Other

·  ↓Intra-ocular pressure

·  ↓Shivering

·  ↓Salivation

·  ↓Platelet aggregation

·  ↓Opioid withdrawal symptoms

 

Limitations of clonidine:

Pharmacokinetic

·  Variable duration of action; 3-7 hours

·  Long t1/2β 12-24 hours

·  2D6 polymorphism -> variable duration

Pharmacodynamic

·  Relating to mechanism of action

o Partial agonist -> less effective

o Less selective than dexmedetomidine (α2:α1 at 200:1 c.f. 1600:1)

·  CVS side effects:

o Acute hypertension with bolus: initial post-synaptic α1

o Compensatory bradycardia

o Rebound hypertension

 

 

 

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