Autonomic Pharmacology - An Overview Flashcards
What type of drug is hexamethonium for neuronal nicotinic receptors?
Non-competitive antagonist
How many transmembrane segments are muscarinic receptors made of?
7
How many subtypes of muscarinic receptors are there?
5
Which muscarinic receptors are important peripherally?
- M1
- M2
- M3
What effects do muscarinic agonists have?
- Decreased heart rate
- Smooth muscle contracts
- Exocrine glands secrete (eg. sweat, salivation, etc.)
Adverse effects of muscarinic poisoning by an agonist
- Bradycardia and vasodilation = falling BP
- Increased motility, bronchoconstriction, pupillary constriction
- Salivation, lacrimation, airway secretions
Treatment of muscarinic poisoning
Atropine (muscarinic antagonist)
What is pilocarpine used to treat and how is it administered?
- Glaucoma
- Topical to the eye
Pilocarpine mechanism of action
- Works on M3 receptors
- Improves aqueous humor drainage
- Drops intraocular pressure
3 non-specific muscarinic antagonists
- Atropine
- Hyoscine
- Cyclopentolate
Clinical uses of antimuscarinic drugs
- Asthma
- Bradycardia
- Decrease secretions and AchEI side effects during surgery
- Dilate pupils
- Urinary incontinence
- Motion sickness
5 main sub-types of adrenoreceptors and what they do
- α1 = contract smooth muscle
- α2 = pre-synaptic auto-inhibition, vasoconstriction, central inhibition of sympathetic outflow
- β1 = increase heart rate + contractility
- β2 = relax smooth muscle
- β3 = relax bladder smooth muscle, stimulate lipolysis
Main uses of α-adrenoreceptor agonists (which receptor and drug)
- Vasoconstrictors with local anaesthetics (α1, (nor)adrenaline)
- Nasal decongestants (α1, phenylephrine)
- Hypertension (α2)
- Facial erythema in rosacea (α2, brimonidine)
Main uses of α-adrenoreceptor antagonists (which receptor and drug)
- Hypertension (α2, doxazosin)
- Benign prostatic hyperplasia (α1, tamsulosin)
Main uses of β-adrenoreceptor agonists (which receptor and drug)
- Cardiogenic shock (β1, adrenaline or dobutamine)
- Anaphylactic shock (adrenaline)
- Asthma (β2, salbutamol)
Main Uses of β-adrenoreceptor Antagonists
- Angina, cardiac arrhythmias
- Hypertension
- Anxiety states
- (Chronic) heart failure
- Glaucoma
What is the main mechanism for terminating actions of noradrenaline?
- Noradrenaline transporter
- Na+, Cl- and noradrenaline cotransported
What does the noradrenaline transporter enhance?
Effects of sympathetic activity
What is the noradrenaline transporter inhibited by?
- Cocaine
- Tricyclic antidepressants (desipramine)
What does desipramine have its major effects on?
CNS
Adverse effects of desipramine
- Tachycardia
- Dysrhythmia
Effects of cocaine
- Euphoria and excitement (CNS action)
- Tachycardia
- Increased blood pressure
What process do mono-amine oxidase inhibitors block?
Breakdown of noradrenaline
What is the clinical use for mono-amine oxidase inhibitors?
Antidepressants
Adverse effects of mono-amine oxidase inhibitors
- Postural hypotension
- Weight gain
- Restlessness
- Insomnia
- Cheese reaction
Examples of mono-amine oxidase inhibitors
- Phenelzine
- Tranylcypromine
- Iproniazid
- Moclobemide
Mechanism of action of indirectly acting sympathetic amines
- Transported into nerve terminals by noradrenaline transporters
- Displace noradrenaline
Effects of indirectly acting sympathetic amines
- Bronchodilation
- Vasoconstriction
- Positive inotropy
- Raised blood pressure
Examples of indirectly acting sympathetic amines
- Amphetamine
- Ephedrine
- Tyramine
