Flashcards in Sedative Hypnotics Deck (41):
Drowsiness, promotes sleep, profound CNS depression
rigidity of the limbs, unresponsive to environmental stimuli
ability to calm, reduce anxiety, mild depression of cerebral cortex
neuroleptic, anxiety reduced w/ no loss of consciousness; hypothalamus and reticular formation fx depression
What is the difference in the mech of action between benzodiazepine and barbiturates?
BZ- binds GABA-a, Cl- influx, membrane hyperpolarization, decreased firing, ONLY in PRESENCE OF GABA
Barb- prolongs the duration of Cl- channels opening; inhibits NE, Ach and Glutamate. Does not req GABA
BOTH result in GABAnergic neurotransmission
What are the therapeutic effects of benzodiazepines?
anxiolytic, muscle relaxant, sedative-hypnotic
What are the pharmalogical effects of benzodiazepines?
dose dependent CNS depression, effects only in presence of GABA
low dose- sedative; high- hypnosis/anesthesia
anterograde amnesia; anti-convulsant
How does benzodiazepine cause muscle relaxation?
potentiation of GABAnergic neurotransmission in the spinal cord
What effects does BZ have on cardio, resp tract and uterus?
Cardio- collapse at toxic dose, but not significant in healthy animals
resp tract- PR and Tidal Volume minimally affected
uterine- crosses placenta, TERATOGENIC
Benzodiazepines do not induce CYP-40
What are the 3 benzodiazepine agonists?
relaxant, tranquilizer, anticonvulsant
minimal effect on cardio/resp
hapatoxic in cats
older animals neuroleptanalgesic
more potent than diazepam
water soluble at low pH
telazol- uscle relaxation, exclusively used w/ tiletamine
What is teh only BZ antagonist?
only reveral agent
competitive antagonist of GABA receptor
Counteract resp depression associated with IV diazepam
ONLY GIVE IV
must give repetitive doeses, can lead to toxicity
may cause seizures, arrhythmia , dizziness
What are barbiturates used for?
anesthesia and seizure management
Barbiturate activity largely depends on _____
Whataare the main 3 barbiturates, their duration of action and major clinical use?
Phenobarbital- long acting; seizures
Pentobarbital- short acting, induction, euthaniasia
Thiopental- ultra short; induction, neurosurgical procedures
What are the 2 major classes of sedative hypnotics?
Phenothiazine derivatives; major tranquilizers
What are the major pharm effects of phenothiazines?
sedation, antiemetic, anti- arrhythmia, anti histaminergic, hypotensice effect, hypothermic effect
What are the 2 major phenothiazines?
What are the 2 major butyrophenones?
used for surgical neuroleptanalgesia in SA sx
FDA approval for swine
sedative and premedicant
controls aggressive behavior
sedation in pigs prior to transport
What is the mech of action of phenothiazines?
blockade of post synaptic mesolimbic dopaminergic receptors (D2)
blockade of alpha-1 adrenergic receptors, H1 histaminergic receptors, and serotonin receptors
What is the site of action of phenothiazines?
basal ganglia, limbic system, thalamus, brain stem, hypothalamus, reticular activating system
What effect do phenothiazines have on the CNS?
depression of brain stem and pathways linking to cerebral cortex
diminished arousal motility, decreased motor activity
anitemetic activity in dogs but not cats
What are extrapyramidal effects?
rigidity, tremors, akinesia
What cardiovascualr effects of phenothiazines
blocks alpha-1 receptor activation in peripheral vascualture- Net result is vasodilation
what is reflex tachycardia?
phenothiazines block alpha-1 receptors, cause peripheral vasodialtion, interpreted by baroreceptors as hypotension, tachycardia develops as result
What are the respiratort effects of phenothiazines
What are the dermatological effects of phenothiazines
promethazine and trimeprazine block H1
T/F phenothiazines produce profound analgesic effects
they dont do this
How do phenothiazines cause hypothermia?
depress thermoregualtion of the hypothalamus;
increased heat loss via vasodialtion
decrease heat pdx via decreased muscle activity
What are butyrophenones used for?
sedative and pre-anesthetic agent
same mech of action as phenothiazines
What CNS effects to butyrophenones have?
potent antiemetic effects
controls drug induced vomiting
What are the cardiopulmonay effects of butyrophenones?
mild hypotension due to blockade of peripheral alpha-1 receptors
minimal effects on CO/resp depression compared to phenothiazines
Adverse effects associated w/ phenothiazines:
accidental intracarotid administration in the horse leads to seizure/death
mimic/similar to clinical signs of organophosphate poisoning - Cholinesterase inhibitor
lower seizure threshold
NO REVERSAL AGENT
Contraindicated in hypovolemic administration