Drugs affecting nerve excitability Flashcards
T/F Both toxins and local anaesthetics bind extracellularly
False, local anaesthetics bind intracellularly
Are local anaesthetics more effective in basic or acidic environments?
Basic
What occurs with general anaesthetics?
Depression of cortal processes for pain/sensory signalling
What are barbiturates main effect?
Depression of the CNS
- sedation > surgical anaesthesia > coma > death
Which type of GABA receptors do benzodiazepines bind to?
GABA A receptors - Ligand gated ion channels
Are there dependence issues/withdrawal symptoms with benzodiazepines?
Yes
Why are some hydrophilic local anaesthetics dependent on nerve activity?
Because they bind to the inactivative state that the Na channels are in after a Na channel has been opened
What is the mechanism of action of local anaesthetics?
Reversible blockage of Na channels
What is clinical efficacy?
The strength of the beneficial effect
Which is faster acting, hydrophobic or hydrophilic local anaesthetics? Why?
Hydrophobic because they can diffuse through membranes and reach the intracellular domain
Which nerves will local anaesthetics affect in a given bit of tissue?
All of them!
What are the side effects of benzodiazepines?
Drowiness
Confusion
Loss of coordination
What is a common side effect of anxiolytics?
A degree of drowiness and sedation
What are benzodiazepines used for?
Epilepsy
Sleep disorders
Anxiety
Pre-surgical
Acute alcohol withdrawal
What are the physiological effects of benzodiazepines?
Sedation and induction of sleep
Amnesia
Muscle relaxant
Reduction of anxiety and anger
Why are benzodiazepines generally prefered to barbiturates?
Less central and cardiovascular effects
No overdose
Less dependence
How does benzodiazepine work in epilepsy?
It enhances the activity of GABA (inhibitory) receptors
What is potency?
The dose of drug required to elicit its effect
What is an example of a hydrophobic local anaesthetic?
Benzocaine
What are the 7 aspects of synaptic transmission that can be targeted by drugs?
Synthesis
Storage
Release
Inactivation
- Reuptake
- Metabolism
Receptor
What are the problems with barbiturates?
Toxic - low therapeutic window
- Induce liver enzymes
- Abrapt withdrawal causes death
Highly addictive
What is anxiety?
The manifestation of the fear response
Which is more sensitive to local anaesthetics, sensory or motor nerves?
Sensory
Are fast or slow acting local anaesthetics dependent on the level of use of a nerve?
Slow
What occurs in local anaesthetics?
Local inhibition of pain and sensory pathways
Describe the level of glutamate in epilepsy
There is too much of it (it’s excitatory)
Describe the level of GABA in epilepsy?
There is too little of it (it’s inhibitory)
How do barbiturates act on GABA receptors?
Prolong opening of the receptor
How does phenytoin act in epilepsy?
Blocks Na+ channels to inhibit excitability
- the channels must be open to be blocked, therefore the nerve must be active
What do benzodiazepines do to their target GABA receptor?
Increase it’s rate of opening and closing
Why are sensory nerve more sensitive than motor nerves to local anaesthetic?
Because they are smaller
