ANS pharmacology 2 Flashcards
○ Propranolol
adrenoceptor antagonist
§ Binds and inhibits B1 and B2
§ Inhibits B1
propranolol effects
□ Decreases heard rate and contractility
□ Reduces cardiac output
□ Decrease blood pressure
propranolol used for
□ Used to treat
® Angina, hypertension, arrythmias, post-myocardial infarction
propanolol side effects
□ May exacerbate bronchoconstriction in asthma
□ May impair circulation in peripheral arterial disease
□ May worsen glycaemia control in diabetic patients
○ Metoprolol
§ Binds and inhibits B1 adrenoceptors
§ Reduces cardiac output and lowers blood pressure
metoprolol used for
§ Used to treat
□ Angina, hypertension, arrythmias, post myocardial infarction
metoprolol side effects
§ Doesn’t block b2 at usual doses
□ May be safer than propranolol in people treated for cardiovascular disease that also suffer for asthma, peripheral vascular disease or diabetes
§ But may block B2 at high doses
□ All beta adrenoceptor antagonists in patients where B2 receptor blockage is problematic
Drugs affecting muscarinic cholinoceptors
- Available drugs often lack selectivity
minimal drugs available
2 muscarinic cholinoceptor agonists
pilocarpine
atropine
- Pilocarpine
○ Muscarinic cholinoceptor agonist
pilocarpine used for
○ Delivered topically to the eye
§ Activate M3 receptors on the surface of the constrictor pupillae muscle
§ Constrict the pupil and promote the drainage of aqueous humous
§ Reduce intraocular pressure
○ Occasionally used clinically to treat glaucoma
§ Not first or second line treatment
- Atropine
○ Blocks all muscarinic cholinoceptor subtypes
antagonist
atropine effects
§ Dries up secretions
□ Saliva, sweat, tears, gut and lung
§ Inhibits smooth muscle contraction
□ Gut, lungs and eye
§ Increases heart rate
○ Also crosses into CNS to block muscarinic receptors
§ Excitatory effects (restlessness, hyperactivity, increase body temp)
atropine used for
○ Atropine is a frontline therapy for poisoning with anticholinesterase agents (pesticides, war gasses)
§ Blocks muscarinic cholinoceptor mediated side effects in CNS and PNS
- Tiotropium
○ Used for chonic obstrictive pumonary disease (COPD)
○ Dilates the airways and reduces mucus secretion
- Tropicamide
○ Used for retinal examination
○ Relaxes ciliary muscle and iris sphincter
- Solifenacin
○ Used for urinary incontinence
○ Relaxes the smooth muscle of the bladder, which increases bladder capacity
2 drugs inhibiting removal of NT
amphetamine and neostigmine
§ Neostigmine
□ Blocks acetyl choline metabolism
reuptake of noradrenaline
Most released NA undergoes neuronal reuptake, (by NA transporter, NAT)
after reuptake of noradrenlaine
§ transported into vesicles by vesicular monoamine transporter, VMAT
§ Or inactivated by monoamine oxidase, MAO
2 inhibitors of NA uptake and metabolism
amphetamine and pseudoephedrine
amphetamine
- induces reverse operation of NAT
○ Inhibits VMAT and MAO
amphetamine effects
○ May cause vasoconstriction (a-AR) and increase in heart rate and contraction (b-AR)
§ Not used clinically for these effects on the autonomic nervous system
§ Used clinically for CNS effects
□ In children with ADHD
- Pseudoephedrine
○ Also increases NA release from adrenergic nerves
○ Use a nasal decongestant is now restricted
§ Can be converted into methamphetamine
Released Ach is metabolised by
enzymes AChE
§ Acetylcholinesterase
- Anticholinesterase
○ Inhibitor of AchE
○ Ach not metabolised and accumulates
- Anticholinesterase causes
○ Mimics stimulation of the parasympathetic nervous system
§ Glandular secretion, smooth muscle contraction, slowing of HR
long actin anticholinesterases
war gasses/poisons
DUMBBELSS symptoms
DUMBBELSS
® Diarrhoea ® Urination ® Miosis/muscle weakness ® Bronchorrhea/bronchoconstriction ® Bradycardia ® Emesis ® Lacrimation ® Salivation/sweating ® Seizures
killer Bs
® Excessive bronchochorrhea, bronchoconstriction or bradycardia can all cause death
therapy for long acting aticholinesterases
□ Atropine is a frontline therapy
® Because it can block the effects of Ach
® Can cross blood brain barrier and prevent CNS effects
medium acting anticholinesterases
□ Hours
□ Neostigmine
short acting anticholinesterases
□ Minutes
□ Edrophonium
clinical use of anticholinesterases in myasthenia graves
□ Autoimmune disease in which body attacks nicotinic receptors on skeletal muscle
□ Extreme skeletal muscle weakness
□ Loss of sensitivity to Ach can be overcome but increasing the concentration of Ach in the neuromuscular juction
diagnosis of myasthenia graves
® Edrophonium
◊ Used for diagnosis of myasthenia gravis
◊ When administered, it causes an increase in muscle strength in people with myasthenia gravis
} Will not cause an increase in muscle strength in people without disease
chronic treatment of myasthenia graves
® Neostigmine
◊ Less useful because it needs to be given by injection
® Pyridostigmine
◊ Orally active
