Sympathomimetics Classifications

Uses Of Sympathomimetics

Classify And Mention Uses Of Sympathomimetics.
Answer:

Sympathomimetics mimics the action of adrenaline or sympathetic stimulation.

Classification Of Sympathomimetics Or Adrenergic Drugs

1. On The Basis of their Mechanism of Action

• Direct-acting sympathomimetics: They act directly as agonists on α and/or β adrenoreceptors, for Example. are adrenaline, noradrenaline, isoprenaline, phenylephrine, methoxamine, xylometazoline, salbutamol, and many more
• Indirect-acting sympathomimetics: They act on adrenergic neurons to release noradrenaline which then acts on the adrenoreceptors, for Example. tyramine and amphetamine
• Mixed-action sympathomimetics: They act directly as well as indirectly, for Example. ephedrine, amphetamine, mephentermine

“Understanding sympathomimetics: Types and mechanisms explained”

2. On the Basis of their Chemical Structure

• Catecholamines: Sympathomimetics with catechol nuclei are called catecholamines, for Example. adrenaline, noradrenaline,
• Non-catecholamines: Sympathomimetics that lack catechol nuclei are called non-catecholamines, for Example, tyramines, ephedrine, amphetamine, phenylephrine, salbutamol, etc.

3. Classification of Adrenergic Drugs Based on Their Therapeutic Uses

• Pressor Agents: Noradrenaline, Phenylephrine, Ephedrine, Dopamine, Methoxamine, Mephentermine.
• Cardiac Stimulants: Adrenaline, Dobutamine, Isoprenaline
• Bronchodilators: Isoprenaline, Salbutamol, Salmeterol, Formoterol, Bambuterol
• Nasal Decongestants: Phenylephrine, Naphazoline, Xylometazoline, Oxymetazoline, Pseudoephedrine
• CNS Stimulants: Amphetamine, Methamphetamine, Dexamphetamine
• Anorectics: Fenflramine, Sibutramine, Dexfenflramine
• Uterine relaxants and vasodilators: Ritodrine, Salbutamol, Isoxsuprine, Terbutaline.

“Impact of beta-adrenergic agonists on cardiovascular health”

Pharmacological Actions Of Adrenaline

• Heart: Adrenaline is a cardiac stimulant. It increases heart rate, increases myocardial contractility, increases conduction velocity, and increases cardiac output as well as oxygen consumption. It also increases the excitability and can lead to cardiac arrhythmias.
• Blood vessels: It leads to the constriction of blood vessels of the skin and mucous membranes which have α1 receptors. It also leads to the constriction of mesenteric, renal, pulmonary, and splanchnic blood vessels. It dilates blood vessels of skeletal muscles and coronary blood vessels which have β2 effect.
• Blood pressure: Due to its action on α1 receptors in the heart and blood vessels it leads to an initial rise in blood pressure and this is followed by a gradual fall in blood pressure, due to the action on β2 receptors in skeletal muscles which causes vasodilatation.

“Treatment options using sympathomimetics in emergencies”

• Respiratory system: It leads to the rapid relaxation of bronchial smooth muscle due to its action on β2 receptors and has a short duration of action. It also stops the release of inflammatory mediators from mast cells. Due to its vasoconstrictor effect, it reduces secretion and relieves mucosal congestion due to the vasoconstrictor effect produced by α1 receptors.
• Gastrointestinal: Adrenaline causes gut relaxation, decreases motility, and constricts sphincters.
• Eye: Adrenergic drugs cause contraction of radial muscles of the iris thus causing mydriasis. They decrease the aqueous formation and thus decrease intraocular tension.
• CNS: Adrenaline at its therapeutic doses does not cross the blood-brain barrier and so effects on CNS are very less.
• Metabolism: It causes an increase in blood glucose levels by stimulating liver glycogenolysis; reducing the secretion of insulin and by decrease in uptake of glucose by peripheral tissues.

“Asymptomatic vs symptomatic use of sympathomimetics”

Therapeutic Uses Of Adrenergic Drugs

• Anaphylactic shock and allergic disorders.
• Hypotensive state: Vasopressor agent can be used.
• Neurogenic or cardiogenic shock: Dopamine or dobutamine is preferred.
• Congestive heart failure: Short-term use in the decompensated state, i.e. dopamine and dobutamine.
• Cardiac arrest: IV adrenaline is used.
• Partial or complete heart block: Ephedrine or isoprenaline can be used.
• Along with local anesthetic adrenaline is used.
• Control of local bleeding: Adrenaline, Phenylephiderine, and ephedrine is used.

“Role of beta-blockers in counteracting sympathomimetic toxicity”

• Nasal decongestant in cold rhinitis: Phenylephiderine, xylometazoline, oxymetazoline are used.
• Stokes­Adam syndrome: IV adrenaline is used
• Bronchial asthma: Beta-2 agonist.
• Mydriatics: Phenylephiderine decreases intraocular tension.
• Obesity: Anorectics like fenfluramine can be used for a short period.
• Uterine relaxant: Isoxsuprine, salbutamol, turbutaline.
• Insulin hypoglycemia: Adrenaline may be used.
• Parkinsonism and hypokinetic children: Amphetamines can be used.