Podcast
Questions and Answers
What is the mechanism of action of adrenaline primarily focused on?
What is the mechanism of action of adrenaline primarily focused on?
How does adrenaline affect intraocular pressure (IOP)?
How does adrenaline affect intraocular pressure (IOP)?
What happens to the bladder wall when adrenaline acts on beta receptors?
What happens to the bladder wall when adrenaline acts on beta receptors?
Which of the following is NOT a systemic effect of adrenaline?
Which of the following is NOT a systemic effect of adrenaline?
Signup and view all the answers
What physiological effect does adrenaline exhibit during anaphylactic shock?
What physiological effect does adrenaline exhibit during anaphylactic shock?
Signup and view all the answers
What effect does adrenaline have on carbohydrate metabolism?
What effect does adrenaline have on carbohydrate metabolism?
Signup and view all the answers
Which adrenergic receptor is responsible for vasoconstriction of ciliary vessels, affecting aqueous humor dynamics?
Which adrenergic receptor is responsible for vasoconstriction of ciliary vessels, affecting aqueous humor dynamics?
Signup and view all the answers
In late pregnancy, what is the effect of adrenaline on the uterus?
In late pregnancy, what is the effect of adrenaline on the uterus?
Signup and view all the answers
Which statement about the metabolism of adrenaline is correct?
Which statement about the metabolism of adrenaline is correct?
Signup and view all the answers
What characterizes the action of sympathomimetics?
What characterizes the action of sympathomimetics?
Signup and view all the answers
Which receptor subtype is primarily responsible for vasoconstriction and mydriasis?
Which receptor subtype is primarily responsible for vasoconstriction and mydriasis?
Signup and view all the answers
What effect do alpha-2 adrenoreceptors generally have on the sympathetic nervous system?
What effect do alpha-2 adrenoreceptors generally have on the sympathetic nervous system?
Signup and view all the answers
Which of the following is a characteristic action of beta-2 adrenoreceptors?
Which of the following is a characteristic action of beta-2 adrenoreceptors?
Signup and view all the answers
Which drug is an agonist for beta-1 adrenoreceptors?
Which drug is an agonist for beta-1 adrenoreceptors?
Signup and view all the answers
What is a key reason sympathomimetic drugs must be stored in dark containers?
What is a key reason sympathomimetic drugs must be stored in dark containers?
Signup and view all the answers
Which of the following effects is associated with activation of beta-3 adrenoreceptors?
Which of the following effects is associated with activation of beta-3 adrenoreceptors?
Signup and view all the answers
Which statement is true regarding adrenaline (epinephrine)?
Which statement is true regarding adrenaline (epinephrine)?
Signup and view all the answers
What type of receptor is primarily targeted by antihypertensive medications such as clonidine?
What type of receptor is primarily targeted by antihypertensive medications such as clonidine?
Signup and view all the answers
Which of the following actions is NOT associated with beta-1 adrenoreceptors?
Which of the following actions is NOT associated with beta-1 adrenoreceptors?
Signup and view all the answers
What is a primary systemic use of adrenaline?
What is a primary systemic use of adrenaline?
Signup and view all the answers
Which adverse effect is most specifically associated with β1-adrenergic receptor stimulation?
Which adverse effect is most specifically associated with β1-adrenergic receptor stimulation?
Signup and view all the answers
In which condition is noradrenaline contraindicated due to the risk of severe complications?
In which condition is noradrenaline contraindicated due to the risk of severe complications?
Signup and view all the answers
What is a pharmacological effect of noradrenaline on blood vessels?
What is a pharmacological effect of noradrenaline on blood vessels?
Signup and view all the answers
What symptom is most likely if extravasation occurs during noradrenaline infusion?
What symptom is most likely if extravasation occurs during noradrenaline infusion?
Signup and view all the answers
Which medication is primarily used to counteract adverse β1 effects?
Which medication is primarily used to counteract adverse β1 effects?
Signup and view all the answers
What effect does Isoprenaline primarily exert?
What effect does Isoprenaline primarily exert?
Signup and view all the answers
Which of the following is a consequence of severe extravasation of noradrenaline?
Which of the following is a consequence of severe extravasation of noradrenaline?
Signup and view all the answers
What is a significant use of dopamine in clinical settings?
What is a significant use of dopamine in clinical settings?
Signup and view all the answers
What is one of the primary adverse effects of isoprenaline due to its β agonistic effects?
What is one of the primary adverse effects of isoprenaline due to its β agonistic effects?
Signup and view all the answers
Which receptor's stimulation primarily leads to peripheral vasodilation effects?
Which receptor's stimulation primarily leads to peripheral vasodilation effects?
Signup and view all the answers
What is the primary effect of dopamine when administered at a moderate dose?
What is the primary effect of dopamine when administered at a moderate dose?
Signup and view all the answers
Which of the following is an adverse effect associated with the use of dopamine?
Which of the following is an adverse effect associated with the use of dopamine?
Signup and view all the answers
Which of the following is NOT a clinical use of fenoldopam?
Which of the following is NOT a clinical use of fenoldopam?
Signup and view all the answers
Which mechanism of action is associated with ephedrine?
Which mechanism of action is associated with ephedrine?
Signup and view all the answers
What consequence can arise from chronic use of nasal decongestants?
What consequence can arise from chronic use of nasal decongestants?
Signup and view all the answers
Which is a primary effect of α1 receptor stimulation when using vasopressors?
Which is a primary effect of α1 receptor stimulation when using vasopressors?
Signup and view all the answers
What is the primary clinical indication for administering dobutamine?
What is the primary clinical indication for administering dobutamine?
Signup and view all the answers
Which effect is directly associated with stimulation of the D2 receptor?
Which effect is directly associated with stimulation of the D2 receptor?
Signup and view all the answers
Which of the following conditions is NOT treated by α1 agonists?
Which of the following conditions is NOT treated by α1 agonists?
Signup and view all the answers
Study Notes
Credit Hours
- Tanta Medical Program
- Credit hours for the program
Sympathomimetics
- Topic: Sympathomimetics
- Presenter: Dr. Ola Mousa Salem
- Interactive session
- Type of session: lesson
- Objectives (ILOs):
- Recognize catecholamine synthesis, storage, and release.
- Identify different types of adrenergic receptors and their function.
- Recognize sympathomimetics (action, uses, side effects, and contraindications).
Autonomic Nervous System
- Diagram showing the autonomic nervous system, its components (nervous system, central, sensory, somatic, motor, ANS), and its divisions (sympathetic and parasympathetic).
Adrenergic Neuronal Transmission
- Diagram illustrating adrenergic neuronal transmission, including catecholamine synthesis, storage, and release (dopamine, norepinephrine).
- Steps in the process are shown:
- Tyrosine to Dopa
- Dopa to Dopamine
- Dopamine to Norepinephrine
- Norepinephrine storage and release
- Norepinephrine metabolism
- Reuptake
- Key players in the process include:
- Tyrosine hydroxylase
- Dopa decarboxylase
- Dopamine β-hydroxylase
- Enzymes (MAO, COMT)
Fate of Neurotransmitters
- Neuronal uptake is a major part of the fate of neurotransmitters.
- Granular uptake (vesicular uptake) is another important process.
- Metabolism by specific enzymes (MAO-COMT).
- Stimulation of presynaptic alpha adrenoreceptors.
Alpha & Beta Adrenoreceptors
- Table explaining the coupling mechanisms of alpha and beta adrenoreceptors.
- Alpha 1 (Gq-coupled) → Phospholipase C → IP3, DAG, Ca²⁺
- Alpha 2 (Gq-coupled) → ↓ Adenylyl cyclase → ↓ cAMP
- Beta (Gs-coupled) → ↑ Adenylyl cyclase → ↑ cAMP
Alpha Adrenoreceptors (α1) (Post)
- Key effects of alpha1 adrenoreceptors:
- Contraction of erector pilae muscle
- Mydriasis (pupil dilation)
- Vasoconstriction
- Viscid salivation
- Gastrointestinal tract (GIT) & urinary bladder (UB) sphincter spasm
- Uterine contraction (during pregnancy), relaxation (outside pregnancy)
- Facilitation of neurotransmission
- Agonist: phenylephrine. Antagonist: prazosin.
Alpha Adrenoreceptors (α2) (Pre & Post)
- Key effects of alpha2 adrenoreceptors:
- ↓ Sympathetic outflow from CNS
- Presynaptic (autoreceptors): influence norepinephrine release
- Reduce release of noradrenaline
- Relaxation of intestinal wall (due to ACh release in enteric ganglia)
- Reduced release of renin and insulin
- Reduced lipolysis in fat cells
- Increased platelet aggregation
- Agonist: clonidine. Antagonist: yohimbine
Beta Adrenoreceptors (β1)
- Key effects of beta1 adrenoreceptors:
- CNS stimulation
- Cardiac stimulation
- ↑ Release of renin
- Lipolysis and free fatty acid release
- Agonist: dobutamine Antagonist: atenolol
Beta Adrenoreceptors (β2)
- Key effects of beta2 adrenoreceptors:
- Generalized vasodilation (VD)
- Bronchodilation
- Stimulate insulin release
- Glycogenolysis in liver and skeletal muscles
- Relaxation of GIT, bladder, and uterus
- Skeletal muscle tremors
- Agonist: salbutamol. Antagonist: butoxamine
Sympathomimetics
- Drugs that stimulate adrenergic receptors.
- Produce effects similar to sympathetic nerve stimulation.
Adrenaline (Epinephrine)
- Sympathomimetic catecholamine found in adrenal medulla and CNS.
- Stored in dark brown ampoules due to chemical instability in alkaline environments.
- Administration routes (not orally, I.V., I.M., S.C., inhalation, eye drops, intracardiac).
- Distribution: Does not pass the blood-brain barrier (BBB).
- Fate: Nerve and tissue reuptake, metabolism by MAO and COMT; excreted unchanged.
- Mechanism of action: Stimulates all adrenergic receptors (alpha 1&2, beta 1&2&3).
- Pharmacological effects (local and systemic).
Local Effects of Adrenaline
- Skin: Subcutaneous (a1) receptor → vasoconstriction
- Mucous membranes (nose): vasoconstriction via a1, decongestion, homeostasis
- Eye: Vasoconstriction of conjunctival blood vessels; no mydriasis (pupil dilation) with adrenaline. (Explain why?)
- Aqueous humor dynamics: a1 → reduced aqueous formation, B2 → facilitation of trabecular outflow.
- Bronchi: Decongestion of bronchial mucosa (a1), bronchodilation (β2)
Systemic Effects of Adrenaline
- CNS: Mild stimulation leads to anxiety.
- Eye: Systemically (a1) → stimulation of dilator papillae muscle → active mydriasis.
- Cardiovascular system: affect heart and blood vessels
- Respiratory system: Bronchodilation, bronchoconstriction
- Gastrointestinal tract: sphincter constriction, intestinal wall relaxation
- Urinary bladder: Bladder sphincter constriction, bladder wall relaxation.
- Uterus: Contraction or relaxation based on pregnancy stage.
Adrenaline (Epinephrine) - Metabolism
- Carbohydrates: Glycogenolysis → hyperglycemia (β2).
- Lipids: Lipolysis → increased plasma free fatty acid (β2 + β3).
- Skeletal muscles...
- Anti-allergic effect.
- Transient hyperkalemia
Adrenaline (Epinephrine) - Uses
- Local uses: Open angle glaucoma, haemostatic nasal pack in epistaxis.
- Systemic uses: Anaphylactic shock, acute bronchial asthma, acute insulin hypoglycemia, cardiac resuscitation, uterine contractions during labor.
Adrenaline (Epinephrine) - Adverse Effects
- CNS: Anxiety, headache
- Alpha effects: Gangrene, hypertension, cerebral hemorrhage.
- Beta effects: Tachycardia, palpitation, angina, arrhythmia.
- Beta 2: Skeletal muscle tremors
Adrenaline (Epinephrine) - Contraindications and Drug Interactions
- Gangrene in fingers and toes
- Hypertension
- Hemorrhagic shock, leading to renal failure and death
- Drug interactions: With digitalis, pulmonary embolism, general anaesthesia.
Noradrenaline (Norepinephrine)
- Natural sympathomimetic catecholamine
- Not orally, does not pass BBB, fate like adrenaline. IV infusion.
- Mechanism of action: Very effective α-adrenergic receptor agonist, limited β2-adrenergic receptor activity.
- Pharmacological Effects
- Cardiovascular system: Generalized vasoconstriction (except coronary), increased blood pressure, bradycardia, increased stroke volume but decreased cardiac output, increased excitability and automaticity (leading to arrhythmia).
Noradrenaline (Norepinephrine) - Uses
- Acute hypotension: during spinal anesthesia or post-operative shock.
- Local anesthetics
Noradrenaline (Norepinephrine) - Adverse Effects
- Necrosis and gangrene if extravasation (leakage outside a vein).
- Hypertension → cerebral hemorrhage.
- Reflex bradycardia
- Headache and anxiety.
Isoprenaline (Isoproterenol)
- Synthetic direct-acting sympathomimetic catecholamine.
- Nonselective β agonist
- Use: Acute heart block, acute bronchial asthma
- Adverse effects: Tachycardia, angina, arrhythmia
Dopamine
- Natural sympathomimetic catecholamine
- Mechanism of action: Stimulates dopaminergic receptors, α and β receptors. DOP receptors: D1, D2, D3
- Peripheral effects: Small dose: D1 → ↑ RBF, moderate dose: D1+β1→ ↑ inotropy, large dose: α1 → ↑ TPR
- Central effects: Limbic system (euphoria, psychosis), Basal ganglia (antiparkinsonism), Hypothalamus (pyrexia,↓ appetite,↓ prolactin secretion), CTZ (Nausea & vomiting)
- Uses: Shock, resistant heart failure
- Side effects: Tachycardia, arrhythmias, nausea, vomiting
Fenoldopam
- Direct selective D1 agonist → vasodilation
- ↓ total peripheral resistance and blood pressure
Alpha-Stimulants
- Stimulation of a1-receptors → vasoconstriction → ↑ total peripheral resistance (TPR) → ↑ blood pressure (BP).
- Uses: Treat hypotension
- Examples: Noradrenaline, Ephedrine, Phenylephrine, Midodrine
Nasal Decongestants
- Topical α1 agonists → vasoconstriction of nasal mucosa.
- Longer duration of action (e.g., 12 hours) than ephedrine.
- Uses: Allergic rhinitis, common cold
- Side effects: Orally → hypertension (cautious use in hypertensives and MAO inhibitors), chronic use → atrophic rhinitis, repeated topical use → rebound congestion.
- Preparations: Oral (pseudoephedrine, phenylephrine); topical (xylometazoline, naphazoline, tetrahydrozoline, oxymetazoline)
Ephedrine
- Mechanism of action: Primarily indirect; some direct action on α and β receptors.
- Effects similar to adrenaline but weaker, slower onset, longer duration, and tachyphylaxis.
Additional notes (from the last page questions)
- A patient receiving intravenous penicillin and diagnosed with anaphylactic shock should be treated with epinephrine, phenylephrine, or norepinephrine.
- Prazosin (alpha-blocker) before norepinephrine can cause sustained hypertension.
- Reflex bradycardia induced by norepinephrine can be blocked by dopamine, isoprenaline, atropine, or ephedrine.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
