Sedatives Flashcards
What is a sedative?
A drug that makes you calm, drowsy and not very responsive to external stimuli
What does high sedation cause?
Sleep, but can be roused (unlike anaesthesia)
What are the types of sedation?
Neuroleptic
Neuroleptanalgsia
What is neuroleptic sedation?
Sedation with effects of phenothiazines or butyrophenones on the CNS
What is neuroelepotanalgesia?
Combination of a neuroleptic and an opioid
What is tranquilliser?
Makes you calm, but alert and responsive
What does a high dose of tranquilliser cause? What is this?
Catalepsy
Altered state of consciousness, can be hyper
What is an anxiolytic?
Drug that reduces anxiety, makes calm
Normal stressful responses doesn’t result in stress response (increased cortisol)
What are the 4 classes of sedatives?
Alpha 2 agonists
Phenothiazines
Butyrophenones
Benzodiazepines
Which classes of sedatives are licensed?
All except benzodiazepines
How do alpha 2 agonists work? What do they cause?
Bind to a2 receptors
Cause sympathomimetic peripheral effects (e.g. vasoconstriction)
Cause sympatholytic CNS effects (e.g. sedation)
How are alpha 2 agonists administered?
Water soluble injection so IV or IM
Molecules lipid soluble so can be orally, SC or epidural
What are the main effects of alpha 2 agonists?
Sedation, analgesia (1/3 of sedation duration), muscle relaxation
= anaesthetic sparing agent
What are the side effects of alpha 2 agonists?
Vasoconstriction causes increased after load on heart Diuresis Hyperglycaemia Muscle relaxation Sweating
What are the advantages to alpha 2 agonists?
Analgesic for some of anaesthetic = anaesthetic sparing agent
Has antagonist available
Atipamezole is the antagonist to alpha 2 agonists. What is a disadvantage of using this antagonist?
Antagonises all effects including analgesia
Overdose causes excitement and hyperalgesia
Give an example of an alpha 2 agonist
Romfidine
Give an example of the only licensed phenothiazine.
Acepromazine
Phenothiazines are antagonists to many receptors. Give examples of some of these receptors and what their antagonist binding causes
A1 adrenoreceptors - vasodilation
Dopamine receptors -sedation
Histamine receptors - anti-emetic and reduced hypersensitivity
Serotonin receptors - anxiolytic
Muscarinic (cholinergic) receptors - reduced parasympathetic tone
How can phenothiazines be administered?
Water soluble injectable = IM, IV
Lipid soluble molecules = SC, orally
Which is the least reliable route for acepromazine and why?
Orally
Least bioavailability
What are the effects of acepromazine/phenothiazinines?
Sedation (less reliable than a2 agonists)
Muscle relaxation
What are the disadvantages of acepromazine?
No analgesia
No anatagonist
What are the side effects of acepromazine/phenothiazines?
Vasodilation
Syncope
Antihistamine
Long lasting
What is syncope?
Temporary unconsciousness
Lack of blood to brain
Common in brachycephalic and excited animals
What is the MOA of butyrophenones?
Similar to phenothiazines - antagonist to lots of receptors
What are the main effects of butryophenones?
Sedation (least reliable)
Muscle relaxation
Anti-emetic, anti-histamien
Long lasting
What are the side effects of butyrophenones?
Long lasting
Vasodilation (less than acepromazine)
NO ANALGESIA OR ANTAGONIST
Give an example of a butyrophenone
Fluanisone
azaperone
How do benzodiazepines work?
Bind to GABA receptor (inhibitory neurotraasmitter)
Give 2 examples of benzodiazepines. Are either of these licensed?
Diazepam
Midazolam
No licensed benzodiazipin!
Why is diazepam not used as much as midazolam?
IV solution expensive
Emulsion form even more expensive
What is a side effect of benzodiazepines?
Causes excitement if used alone
Overdose causes excitement
Which is the only group of sedatives to have analgesic effects?
Alpha 2 agonists
Only for 1/3 of sedative effect
Which are the 2 groups of sedatives to have antagonists?
Alpha 2 agonists
Benzodiazepines
