SYMPATHOMIMETICS Flashcards
Constitute a group of drugs used for
- Cardiovascular
- Respiratory
- Other conditions
Adrenomimetics
Adrenomimetics
Subdivided into:
Mode of action
Direct-acting
Indirect-acting
Adrenomimetics
Subdivided into:
Spectrum of action
Alpha
Beta
Dopamine receptor affinity
A. MODE OF ACTION
Bind to and activate the adrenoceptors
Result to sympathetic stimulation
DIRECT-ACTING SYMPATHOMIMETICS
A. MODE OF ACTION
Displacement of stored cathecolamines in
the synapse
Tyramine, amphetamine
INDIRECT-ACTING SYMPATHOMIMETICS
A. MODE OF ACTION
Inhibit the reuptake of cathecolamines by
nerve terminals
Cocaine, tricyclic antidepressants
INDIRECT-ACTING SYMPATHOMIMETICS
Present in the mitochondria in the adrenergic nerve endings
Inactivates portion of dopamine and norepinephrine in the cytoplasm
MONOAMINE OXIDASE (MAO)
May increase the stores of these transmitters and other amines in
the nerve endings
MONOAMINE OXIDASE INHIBITORS
subgroups of alpha
alpha 1
alpha 2
subgroups of beta
beta 1
beta 2
beta 3
Single prototype with effects at all receptors
Alpha1 and alpha2
Beta1,beta2 and beta3
EPINEPHRINE
Separate prototype
Alpha
PHENYLEPHRINE
Separate prototype Beta Synthetic cathecolamine Similar to the endogenous transmitters Not readily taken up into the nerve ending
ISOPROTERENOL
B. SPECTRUM OF ACTION
Constitute a third class of adrenoceptors Drugs mentioned have little effect on dopamine May act as a potent dopamine receptor agonist itself
DOPAMINE
Epinephrine, norepinephrine, and dopamine
Endogenous adrenoceptor agonists
Rapidly metabolized by COMT and MAO
Inactive when given by the oral route
Short duration of action
When given IV, they do not enter the CNS
in significant amounts
CATHECOLAMINES
Not a cathecolamine Resistant to MAO Resistant to COMT Orally active Enter the CNS Longer effects
AMPHETAMINES
Presence of OH groups at carbons 3 and 4
Degraded by cathecol-o-methyl transferase
(COMT)
PHENYLETHYLAMINE
PHENYLETHYLAMINE
Removal of OH will:
Make it resistant to COMT
Prolong the duration of action
Increase bioavailability
Increase the ability to penetrate the CNS
Alter the alpha carbon, add CH3
Phenylisopropylamine
Ephedrine, amphetamine
PHENYLETHYLAMINE