- أول مستوى دواء علم

. دماج أمين محمد د

SympathomimeticsDefinition

Drugs that stimulate adrenoceptors and produce actions similar to sympathetic system

1-Catecholamines 2-Non catecholamines

A-Natural B-Synthetic

1-dopamine

2-nor adrenaline

3-adrenalin

1 -isoprenaline

2-dobutamine

3-isoetharine.

1-Ephedrine,

2-amphetamine,

3-phenylephrine

4-salbutamol.

Mechanism of action of sympathomimetics

A-Direct

1-catecholamines

2-phenylephrine

3-salbutamol

1 -Amphetamine

2-Tyramine

1-Ephedrine.

B-Indirect C-Mixed (dual)

Catecholamine drugs

1-Adrenaline :

Mechanism of action

Stimulates directly all types of receptors α – β Administration of adrenaline

S.C , Inhalation , Intra-cardiac , Eye drops.

Action of adrenaline

Uses of adrenaline(indications)

1. In allergy (anaphylactic shock).

2.With local anesthetics.

3.Epistaxis (locally).

4.Hypoglycemia.5.Glaucoma (dipivifrin is better , a prodrug).

6. Cardiac arrest (intracardiac).

7.Acute bronchial asthma.

Contraindications of adrenaline :-

1. Hypertension.

2.Arrhythmia .3.Angina pectoris .

4.Thyrotoxicosis .

5. With local anesthetics in fingers & toes → gangrene .

6.With digitalis and some general anesthetics as halothane → arrhythmias.

7. With non selective β-blockers → severe hypertension.

2-Noradrenaline

Mechanism of action

Stimulates directly α-β1 , β3 no β2

Administration of Noradrenaline

I.V. infusion.

Uses of adrenaline(indications)

1-Acute hypotension Infusion( should not be stopped suddenly).

3-Isoprenaline (isoproterenol)

Mechanism of action

Stimulates directly β1 , β2, β3 but no α-effct

Administration of Iso prenaline.

- Sublingual, Inhalation

Uses of Isoprenaline(indications)

1-Heart block.

2-Acute bronchial asthma.

4-Dopamine

Mechanism of action

Stimulates directly D1 , β1 , α receptors.

Administration of dopamine

I.V. infusion. It can't pass to brain.

Small dose → ↑ D1 → V.d. of renal & mesenteric vessels .

Moderate dose →↑ D1 and β1 ↑ H.R., ↑ C.O., ↑ systolic pressure .

Large dose → α1 V.C.,↑T PR., BP.

Uses of Dopamine (indications)

1-Hypovolemic, cardiogenic &endotoxin shock with correction of hypervolemia.

5-Dobutamine

Mechanism of action

Stimulates directly β1 receptors

Administration

I.V. infusion Uses of Dobutamine (indications)

1-acute heart failure (cardiogenic shock).

6-Fenoldopa- D1 receptor agonist which decreases P.R. by dilating arterioles.

- It is given by I.V. drip in emergency hypertension.

Side effects :

1-Headache, 2-Flushing 3-Tachycardia.

1-Non-Catecholamines drugs

A)β – stimulants B)α – stimulants

1-Selective β2 agonistsEx. Salbutamol

3-Non Selective β agonistsEx. Adrenaline

1-Selective α1 agonistsEx. Phenylephrine

2-Selective α2 agonistsEx. Clonidine

2 -Selective β1 agonistsEx. Dobutamine

3-Non Selective α agonistsEX. Adrenaline , Noradrenaline

1-Selective β2 agonists

A) β – stimulants

3-Non selective β-agonists

1-Salbutamol (ventolin)

2-terbutalin (Bricanyl 3-salmetrol (Serevent)

4-formoterol (foradil )

2- selective β1-agonists

Action of selective β2 agonist1- Produce broncho dilatation,

2- ↓ bronchial secretions & ↓ release of allergic mediators from mast cells.

3- Relax uterus & produce V.D.

4- ↓ B.P. & produce mild tachycardia (reflex and weak

β1 effect).

5- ↑ glycogenolysis& insulin release .

Clinical Uses 1 -in bronchial asthma. (acute attack & prophylaxis).

Side effects:- 1 -Tremors 2-tachycardia 3 -nervousness.

Ritodrine -: β2 agonist, used in

1- premature labour

2-constriction ring of uterus

3- dysmenorrhea.

Non selective β-agonists

1-Isoxsuprine 2-Oriciprenaline

Used in 1-vascular disease

2-constriction ring of uterus.

Used orally or inhalation in bronchial

asthma

B) α – stimulants

1-Selective α1 agonistsEx. Phenylephrine

2-Selective α2 agonistsEx. Clonidine

2-Non Selective α agonists

EX. Adrenaline , Noradrenaline

1-Phenylephrine oral, local, injection.

2-Midodrine oral (prodrug).

3-Methoxamine injection.

Action of Selective α1 agonist1-Produce V.C. → decongestant

2 -↑P.R ,.3 -↑B.P. (systolic & diastolic). → reflex

bradycardia4-Active mydriasis (+ ve L.R.).

Clinical Uses1. Treatment of hypotension.

2.Treatment of Paroxysmal Atrial Tachycardia ( PAT).

3.mydriatic& decongestant (phenylephrine).

Nasal decongestant

A)Local B)Systemic (oral)

1. Naphazoline (Privin)

2. Xylometazoline (otrivin, Rhinex , Balkis)

3. Tetrahydrozoline(Nazine)

4. Oxymetazoline (Afrin ,oxymet)

Non –irritant nasal drops and sprays (less rebound congestion).

B)Systemic (oral)

1-Phenylpropanolamine (coldact,Flustop ,Eskornade).

2-Pseudoephedrine.(Actifed ,Histarhine,Doldex-2):oral common cold preparation

3-Phenylephrine (α1 agonist).(Noflu , Sine –up): oral

common cold preparation

THANK YOU Dr. Mohammad dammage