DRUGS OF THE SYMPATHETIC NERVOUS SYSTEM

Question 1

DRUGS OF THE SYMPATHETIC NERVOUS SYSTEM can be classified based on what?

Answer 1

1. classified based on chemical structure
2. classified based on mode of action
3. classified based on therapeutic uses

Question 2

Classification based on chemical structure

Answer 2

1. Catecholamines
2. Non catecholamines

Question 3

Difference between Catecholamines and non-catecholamines

Answer 3

Catecholamines:
1. Sympathomimetic amines having catechol nucleus
2. Not effective orally
3. Easily metabolised by monoamine oxidase
4. Action quick compared to non- catecholamines
5. Doesn’t readily crosses BBB
6. No significant CNS effects
7. Act directly on receptors
Eg - epinephrine, nor - epinephrine

Noncatecholamines:
1. Devoid of catechol nucleus
2. Effective orally
3. Relatively resistant to monoamine oxidase enzyme
4. Action prolonged as compared to catecholamines
5. Easily crossess BBB
6. Have significant CNS effects
7. Act indirectly as well as directly
Eg - amphetamine, ephedrine

Question 4

Classification based on therapeutic uses
U CAN PCB

Answer 4

1. Pressor agents
   Noradrenaline, Phenylephrine, Ephedrine, Methoxamine, Dopamine, mephentermine

II. Cardiac stimulants
Adrenaline, Dobutamine, Isoprenaline

III. Bronchodilators
Isoprenaline, Salmeterol, Salbutamol, Formoterol, (Albuterol) Bambuterol
Terbutaline

IV. Nasal decongestants
*Phenylephrine Naphazoline, Xylometazoline, Pseudoephedrine ,Oxymetazoline, Phenyl propanolamine

V. CNS stimulants
*Amphetamine, Methamphetamine, Dexamphetamine

VI. Anorectics
*Fenfluramine, Sibutramine, Dexfenfluramine

VII. Uterine relaxant and vasodilators
*Ritodrine, Salbutamol, Isoxsuprine, Terbutaline

Question 4

Classification based on mode of action

Answer 4

Direct acting sympathomimetic drugs
Indirect acting sympathomimetic drugs
Mixed acting

Question 5

DIRECT ACTING SYMPATHOMIMETICS

Answer 5

they exact their effects by stimulating adrenergic receptors and are therefore known as adrenergic receptor agonist.

Agonist is a drug that binds to receptors activates the receptors and produce an effect

Question 5

INDIRECT ACTING SYMPATHOMIMETIC and examples
Adverse effects and uses of amphetamine

Answer 5

Eg. Amphetamine, tyramine, ephedrine

indirectly increase the levels of the neurotransmitter in the synaptic cleft

they are taken up into the adrenergic nerve terminal by a high-affinity neuronal transport systems where they promote the release of nor-adrenaline from storage pool.

Amphetamine: is a drug of addiction and a strong CNS stimulant.

It’s psychomotor stimulants effect of amphetamine accounts for its, ability to elevate mode, increase motor performance and concentration it increases self confidence, speech and resistance to fatigue.

USES
Obesity: amphetamine can be used to aid weight loss through suppression of apetite rather than promoting energy expenditure
it is a classical CNS stimulants or excitation

treatment of narcolepsy
it induces excessive sleep even in an enviroment that is not conducive for sleep
it is used in the treatment of this condition, however, many cause day time attack of sleep in this patient due to disturbancy of nocturnal sleep.
Treatment of hyperactive attention deficit especially in children.
this condition is experienced in people who lack attention and never do well in class.
some adults still have such lacking attention span and such adults have dull memory span.

Question 5

MIXED ACTING SYMPATHOMIMETIC DRUG and examples
Uses of Ephedrine

Answer 5

it is described as mixed acting sympathomimetics, it promotes the release of NA from the storage site which now stimulates adrenergic receptors e.g ephedrine

USES OF EPHEDRINE
treatment of asthmatic attack because it can cause bronchodilation
it is used as nasal decongestants e.g pseudoephedrine which present in artifact.

Question 6

classification of adrenergic receptor

Answer 6

Non-selective (α and β) receptor agonist e.g nor-adrenaline and adrenaline.
Nor-adrenaline found in the nerve terminals while the adrenaline found in the adrenal medulla.

Non-selective α1,α2 e.g. oxymetazoline (nasal decongestant)
Non-selective β1,β2 e.g. isoproterenol (increase heart rate in heart block)
Non-selective α1,α2, β1,β2 e.g. epinephrine
Non-selective α1,α2, β1 e.g. norepinephrine

β1- adrenergic receptors

α1 receptor selective agonist: e.g phenylephrine they are found in the blood vessels, GIT and liver
they cause vasoconstriction
relaxation of smooth muscles of GIT
they cause glycogenolysis in liver
they are pressure agent in hypertension
they act as a nasal decongestant

α2 selective receptor agonist: clonidine
they are found in the adrenergic nerve terminal
used in the treatment of hypertension
and also the treatment of drug addiction

β- non selective receptor agonist: isoprenaline
they are found in the ciliary muscle and heart
it increases the rate of contraction
as a cardiac stimulant in heart block
bronchodilators in asthmatic patients
causes relaxation of ciliary muscle.

β1- selective agonists: dobutamine
found in the GIT, cardiac muscle and blood platelets, heart.
used as a cardiac stimulants on a failing heart

β2- selective agonists: salbutamol
found in the bronchial smooth muscles, respiratory smooth muscle, uterine smooth muscle. Used for asthma treatment

Question 7

CLASSIFICATION OF ADRENERGIC RECEPTOR ANTAGONIST

Answer 7

Non selective adrenergic receptor antagonist
α non selective antagonists.

α1 selective antagonist
α2- selective antagonist
β1 and β2 blockers
β1 selective blocker
β2 selective blockers