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What are the potential adverse effects of adrenaline related to cardiac rhythm?
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Adverse effects can include arrhythmias and ventricular fibrillation due to increased cardiac action.
Why is adrenaline contraindicated in patients with hyperthyroidism?
Hyperthyroidism results in beta receptor upregulation, increasing sensitivity and effects, which makes adrenaline use risky.
What are the characteristics of catecholamines that differentiate them from non-catecholamines?
Catecholamines contain a catechol ring, are not absorbed orally, don't cross the blood-brain barrier, and are metabolized quickly by MAO and COMT.
What are the main types of adrenergic receptors involved in sympathomimetic activity?
Alpha 1, alpha 2, beta 1, beta 2, and beta 3 adrenergic receptors.
How might adrenaline result in pulmonary edema?
Adrenaline can cause pulmonary edema due to its effects on increased heart contractility and systemic vasoconstriction.
Explain why non-catecholamines can cross the blood-brain barrier but catecholamines cannot.
Non-catecholamines lack the polar catechol ring structure, permitting them to cross the blood-brain barrier.
How do direct acting sympathomimetics differ from indirect acting ones?
Direct acting sympathomimetics directly stimulate adrenergic receptors, while indirect acting ones cause the release of norepinephrine or inhibit MAO to prevent norepinephrine breakdown.
What precautionary measures should be considered when using adrenaline in hypertensive patients?
Avoid using adrenaline due to the risk of exacerbating high blood pressure and potential cerebral hemorrhage.
How does the use of adrenaline in local anesthesia contribute to reduced bleeding?
Adrenaline causes vasoconstriction, which reduces blood flow to the area and consequently minimizes bleeding.
In what emergency situations is adrenaline commonly used, and by which routes?
Adrenaline is used in acute anaphylactic shock, acute bronchospasm, and cardiac arrest, typically administered intravenously.
What are the cardiovascular effects of adrenaline at therapeutic doses?
Adrenaline at therapeutic doses increases systolic blood pressure and decreases diastolic pressure.
What molecular mechanism does adrenaline trigger when acting on alpha 1 receptors?
Adrenaline increases IP3 and calcium levels in cells when acting on alpha 1 receptors.
Describe the mechanism of action of adrenaline on alpha and beta adrenergic receptors.
Adrenaline activates all adrenergic receptors, increasing IP3 and calcium via alpha 1 and increasing cyclic AMP via beta receptors.
Why is adrenaline not absorbed orally?
Adrenaline contains a catechol structure that prevents oral absorption due to rapid metabolism by MAO and COMT.
What happens to adrenaline after it is metabolized in the body?
After metabolism, adrenaline is excreted as metanephrine or vanillylmandelic acid.
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