Small Animal Psychopharmacology Flashcards
What are the common categories of major behavior problems?
- aggression
- compulsive disorders (stereotypies)
What drug effects do we typically try and produce for aggression?
- increase central seratonergic activity
- decreases tendency to have sudden outbursts
- increases threshold of tolerance to potentially aggressive stimuli
What types of drugs can be beneficial for compulsive disorders?
- TCA’s
- SSRI’s
- opioid antagonists
What are the pharmokinetics of psychotrophic drugs?
- many are weak bases
- good lipophilicity
- protein binding is generally low
- CNS penetration generally good
- most metabolized by liver
What are the principle anxiolytics in vet med?
Benzodiazepines
What do anxiolytics do?
- potentiation of GABA receptors
- anxiolytics effects are seperate from general CNS depressant effects (dose-related)
What are the key characteristics of benzodiazepines?
- safe
- disinhibition possible (inability to control impulses, avoid use in aggression)
- paradoxical excitement and amnesia possible
- sedation, muscle relaxation, ataxia and hyperphagia
What is flumazenil?
- BZD antagonist
- may be used to reverse overdose of BZD or reverse unwanted behaviour
What are the key characteristics of diazepam?
- short half-life
potentially disappointing for immediate effects
What are the key characteristics of alprazolam?
- BZD used as an anxiolytic
- higher potency BZD
What are the key characteristics of Lorazepam?
- BZD used as anxiolytic
- not as extensively metabolized by the liver
- advantages in liver failure
What are the key characteristics of buspirone?
- azapirone class anxiolytic
- does not compete directly with BZDs
- used for generalized anxiety - poor immediate effects
- less sedating and other side effects than BZDs
What classes of drugs does the general category of antidepressants include?
- tricyclic antidepressants (TCA’s)
- selective serotonin re-uptake inhibitors (SSRI’s)
- monoamine oxidase inhibitors (MAOIs)
What is the general mechanism of action of an antidepressant?
Altering primarily NE and serotonin (5-HT) levels in the CNS
What is the mechanism of action of tricyclic antidepressants?
- inhibit re-uptake of NE and 5-HT, increasing levels in the CNS
What do we use TCA’s for?
- they reduce high arousal and reduce anxiety
- used to manage mild aggression, anxiety, some compulsive disorders in dogs used to manage inappropriate urination, aggression and anxiety in cats
What are the adverse drug reactions associated TCA’s?
- they possess cholinergic and adrenergic blocking effects
- CV, GI, UT effects
- produce sedation
What is the mechanism of action of clomipramine?
Primarily blocks 5-HT re-uptake
What do we mainly use clomipramine for?
- anxiety
- stereotypies
- anti-aggressive effects
- storm and noise phobias
What do we use amitriptyline for?
- behavior modification and pain mgmt
- more selective for 5-HT reuptake vs NE reuptake
- separation anxiety, compulsive disorders and aggression in dogs
- anxiety, psychogenic alopecia and idiopathic interstitial cystitis in cats
What effects do serotonin-selective re-uptake inhibitors have?
- classified as antidepressants but display many effects such as anxiolytic and panic disorder
What are the adverse effects of SSRIs?
- generally very safe
- serotonin syndrome when combined with 5-HT agonists, MAOIs, TCAs, OTC herbal supplements
- most common complaint is sedation and anorexia
What is the MOA of fluoxetine?
- blocks 5-HT reuptake
- it is metabolized to an active metabolite and has a long wash out
What would we used an opiate antagonist for?
- some stereotypic compulsive behaviors
- some like self-traumatic licking may release endorphins and reinforce these behaviors
- naltrexone is an example but very expensive
What would we use antipsychotics for?
- limited to short term and intermittent use as needed
- chemical restraint
- intense fear
- blocks central dopamine receptors
- many adverse CNS and CV effects (sedation, decrease BP, inhibit learning, extrapyramidal effects)
What are some low potency antipsychotics we use?
- Acepromazine
- Chlorpromazine
What would we use hormones for?
- used as a last resort when newer/safer approaches have failed
- example: progestins (medroxyprogesterone acetate)
What would we use pheromones for?
- stress or fear associated with the environment
- produces a calming effect
When would we use anticonvulsants behaviorally?
- behavior problems that may have a seizure basis
- example: gabapentin
What is the mechanism of action of trazadone?
- produces NE and 5-HT reuptake inhibition
What would you use dexmedetomidine for?
Oral transmucosal delivery in a gel approved for noise phobias in dogs
What are some possible drug combinations for behavior?
- partial 5-HT receptor agonist with an SSRI = increased serotonin levels
- combining antidepressants with rapid onset agents (BZD with TCA or SSRI)
What are common ADRs with combination therapy?
- altered metabolism of one drug by another = failure or toxicity
- increased effects of multiple drugs acting on the same NT system
