Sedative Hypnotics Flashcards by Nic Lauterbach

Define hypnotic

Drowsiness, promotes sleep, profound CNS depression

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Define catalepsy

rigidity of the limbs, unresponsive to environmental stimuli

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Define anxiolytic

anxiety relieving

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Define sedative

ability to calm, reduce anxiety, mild depression of cerebral cortex

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Define tranquilizer

neuroleptic, anxiety reduced w/ no loss of consciousness; hypothalamus and reticular formation fx depression

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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

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What are the therapeutic effects of benzodiazepines?

anxiolytic, muscle relaxant, sedative-hypnotic

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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

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How does benzodiazepine cause muscle relaxation?

potentiation of GABAnergic neurotransmission in the spinal cord

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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

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T/F

Benzodiazepines do not induce CYP-40

TRUE

Barbiturates do

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What are the 3 benzodiazepine agonists?

Diazepam

Midazolam

Zolazepam

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Diazepam

long T1/2
crosses BBB
relaxant, tranquilizer, anticonvulsant
minimal effect on cardio/resp
Neuroleptanalgesia
hapatoxic in cats

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Midazolam

older animals neuroleptanalgesic
more potent than diazepam
water soluble at low pH
IM/IV

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Zolazepam

telazol- uscle relaxation, exclusively used w/ tiletamine

induction agent

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What is teh only BZ antagonist?

Flumazenil

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Flumazenil

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 _____

lipid solubility

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

Butyrophenone derivitives

What are the major pharm effects of phenothiazines?

sedation, antiemetic, anti- arrhythmia, anti histaminergic, hypotensice effect, hypothermic effect

What are the 2 major phenothiazines?

chlorpromazine

acepromazine

What are the 2 major butyrophenones?

droperidol

azaperone

Droperidol

used for surgical neuroleptanalgesia in SA sx psychomotor depression

Azaperone

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?

sedation depression of brain stem and pathways linking to cerebral cortex diminished arousal motility, decreased motor activity extrapyramidal symptoms 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

minimal effects

What are the dermatological effects of phenothiazines

promethazine and trimeprazine block H1

T/F phenothiazines produce profound analgesic effects

FALSE 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

Therapeutic uses of phenothiazines/butyrophenones

tranquilizers pre-anesthetic in general anesthesia, allows dose reduction and amelioration of adverse effects associated w/ some anesthetic agents antiemetics