VPT 321: Veterinary Neuropharmacology (2+1) copy 1

DIFFERENCE BETWEEN CATECHOLAMINES AND NON CATECHOLAMINES

• Adrenergic drugs are divided into catecholamines and non catecholamines. The difference between catecholamine and non catecholamines is follows:

Catecholamines	Non catecholamines
Contain hydroxyl groups at position 3 and 4 on the benzene ring	Lack one or both hydroxyl groups on benzene ring
Mainly have direct action. Few compounds may have mixed action (like dopamine)	Mainly have indirect or mixed actions and few may have direct action (like phenylephrine)
Have high affinity for α and/or β receptors	Have moderate to poor affinity for adrenoceptors
Usually have shorter half life because of their rapid metabolism	Have moderate to longer half life as these are degraded slowly
Metabolised mainly by MAO or COMT	Poor substrates for MAO and resistant to COMT
Usually not effective by oral route and are given parenterally	Most of the drugs are effective orally
Being polar drugs, poorly penetrate the CNS and hence have minimal effect on CNS	Easily pass blood brain barrier and produce significant CNS effects
Effects are produced even after adrenergic denervation	Loose activity following adrenergic denervation
No development of tolerance	Tolerance develops following repeated administration