BIOM 3090 Lecture Notes - Lecture 16: Intracerebral Hemorrhage, Coronary Artery Disease, Monoamine Oxidase Inhibitor
9 Jun 2018
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Indirect acting sympathomimetic
1. Tyramine: found in some cheese’s and fermented foods
a. Normally metabolized by MAO during first pas through liver
b. If taking MAO inhibitor, tyramine from diet not metabolized
c. Tyramine → increase NE release (can be toxic → sympathetic excess)
2. Amphetamine: stimulates release of NE
3. Cocaine: prevents re-uptake of NE
- across BBB – stimulate CNS
Clinical pharmacology of adrenergic drugs
- Why is cocaine sometimes administered for nasopharyngeal surgery?
o ANS: cocaine inhibits NE re-uptake - increases NE —> activates alpha1 receptors of
blood vessels —> reduces blood flow (reduction in bleeding)
o Cocaine can prolong effect of anaesthetic and also has anaesthetic properties
- Which other sympathomimetic drugs could prolong the duration of action of a local
anaesthetic?
o ANS: any drug that increases NE or activates alpha1 (ex. amphetamine)
- What adrenergic drug could be used to:
o Reduce blood loss due to haemorrhage?
o Relax the uterus during premature labour?
o Treat an overactive bladder?
Toxicities associated with sympathomimetics
- Toxicities = extension of pharmacological effects in cardiovascular system and CNS
- Cardiovascular system
o 1 agonists → tachycardia → arrhythmias/myocardial damage
o agents that increase BP → increase cardiac work → heart failure, cardiac arrest,
stroke
o elderly and patients with high BP, previous HR or coronary artery disease
particularly at risk
- CNS
o Toxicity rarely observed with direct agonists
o Indirect agonist: (multiple transmitters affected, NE, dopamine and serotonin)
restlessness, tremor, insomnia, anxiety
o Cocaine → convulsions and cerebral haemorrhage in addition to risk of arrhythmias
and heart attack
Adrenergic antagonists
- block or receptors normally activated by NE or epinephrine
ALPHA
Prazosin
1 >>>>2
ALPHA
Yohimbine
2 >> 1
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Document Summary
Which other sympathomimetic drugs could prolong the duration of action of a local anaesthetic: ans: any drug that increases ne or activates alpha1 (ex. amphetamine) Toxicities = extension of pharmacological effects in cardiovascular system and cns. Cns: toxicity rarely observed with direct agonists, indirect agonist: (multiple transmitters affected, ne, dopamine and serotonin) restlessness, tremor, insomnia, anxiety, cocaine convulsions and cerebral haemorrhage in addition to risk of arrhythmias and heart attack. Block or receptors normally activated by ne or epinephrine. Eye: block 1 constriction of pupil (miosis, block decrease secretion of aqueous humor from ciliary epithelium. Heart: blocks 1 decrease hr/force of contraction. Blood vessels: 1 vasodilation (organs/skin, 2 vasoconstriction (skeletal muscles) Inhibition of 1 decrease hr/force of contraction: baroreceptors detect decrease in bp decrease psns and increase sns vasoconstriction via 1 (organs and skin, e. g. Inhibition of 1 in blood vessels vasodilation: baroreceptors detect decrease in bp decrease psns and increase sns increase hr via 1.
