Psychopharmacology

Soma

Soma

Cell body

Dendrites

Responsible for taking signals from other neurons to the stoma

Axon

Conduction unit

Presynaptic terminal

Secrete neurotransmitters to other cells

What does the cerebellum do?

Responsible for attention, cognition, and coordination

What consists of the hindbrain?

Brain stem and cerebellum

What is part of the brain stem?

• pons

• Medulla oblongata

What does midbrain consist of?

Tegmentum and rectum

What is the largest axon pathway?

Corpus callosum

How do animals present with forebrain tumors?

• seizures

• Circling

• Blindness

• Behavior changes

How do animals present with a hindbrain tumor?

• mentation changes

• Ataxia

• Head tilt

• Nystagmus

• Paresis

• Hemiparesis

What does cerebral spinal fluid do?

Provides nutrients to cells, a cushion for the brain, and a conduit for hormones

What medications can cross the blood brain barrier?

• lipid soluble

• Unionized

• Non-polar

What are the most common neurotransmitters?

• Acetycholine

• Monoamines

• GABA receptors

• Glutamate

What is Acetylcholine associated with?

Perceptual learning and formation of memory

List some Monoamines.

• dopamine

• Norepinephrine

• Epinephrine

• Serotonin

What is dopamine associated with?

Autonomic nervous functions

• sociability

• Cognition

• Motivation

What is serotonin associated with?

• mood

• Arousal

• Metabolism

• Anxiety

• Pain response

What does gamma-aminobutyric acid?

• reduces anxiety

• Promotes sleep

• Promotes muscle relaxation

• Reduce seizure activity

How many binding sites does gamma-aminobutyric acid have?

5

• GABA

• Benzodiazepines

• Barbiturates

• Steroids

How many receptors does glutamate have?

3 receptors

Why is understanding receptors and neurotransmitters important?

Help in the deciding factor when we are picking medications and how we expect them to effect the brain

Pharmokinetics

The movement of drugs into, through, and out of the body and includes the processes of absorption, distribution, metabolism, and excretion

What helps determine efficacy of the drug?

Binding affinity and specificity with receptors

Where are drugs metabolism?

Liver

Steady State

When repeated administration leads to equilibrium between blood level and excretion

Therapeutic Window

The range of blood levels that provide for drug efficacy

What are the three purposes of medications?

• drug desensitization

• Failure of behavior management alone

• Address a problem that has a medical component

Desensitization

Agonizing or antagonizing neurotransmitters to re-establish “normal” responses to the environment

What pathologies can we treat? (5)

• anxiety

• Fear/phobia

• Compulsive disorders

• Cognitive dysfunction

• Aggression

What are Phenothiazines?

Dopamine antagonists which increase spontaneous behavior

What are phenothiazines most often used for?

• behavioral reasons

Side effects of phenothiazines

• tranquilization

• Hypotension

• Reduced seizure threshold

• Movement disorders

Examples of Anxiolytics

• benzodiazepines

• Azapirones

• Antihistamines

• Barbiturates

Side effects of benzodiazepines

• sedation

• Decreased anxiety

• Muscle relaxation

• Seizure control

• Increased appetite

• Memory deficits

• Paradoxical excitement

• Liver necrosis

What is important about taking a patient of benzo.?

wean and lower the dosage

Examples of Benzos.

• diazepam

• Alprazolam

• Clonazepam

What is the most commonly used azaprione?

Buspirone

How long can it take azapriones to build up the desired effect?

4-6 weeks

Categories of Antidepressants (3)

• TCA: tricyclic antidepressants

• SSRI: selective serotonin reputable inhibitors

• MAOIs: Monoamines oxidase inhibitors

How do TCA’s work?

Inhibit reuptake of norepinephrine and 5-HT at the presynaptic membrane

What are TCAs used for? (3)

• separation anxiety

• Compulsive disorders

• Urine marking

What are examples of TCAs? (3)

• Clomicalm

• Amitryptyline

• Tofranmil

Which has a narrower therapeutic range: SSRIs or TCAs?

SSRIs

When should you not give TCA’s?

• animals with ocular abnormalities

• Animals with thyroid disease

• Cardiac issues

How long do you have to wait to give a MAOI after treating with a TCA?

14 days after you stop giving the TCA

What TCA should you not give aggressive dogs?

Clomipramine because it can exacerbate the problem

When can serotonin syndrome occur?

When a patient ingests more than the prescribed dose of a serotonin producing drug or time between starting and stopping MAOI, TCAs, or SSRIs was not adequate

Clinical Signs of Serotonin Syndrome (5)

• muscle tremors

• Muscle rigidity

• Changes to mentation

• GI upset

• Tachycardia

How do you treat serotonin syndrome?

Emesis and there activated charcoal to bind to any remaining drug in the body, IVF supportive care

What do SSRIs do?

Inhibit reuptake of 5HT at the pre-synaptic membrane

• DESENSITIZE THE RECEPTOR AS WELL

List 3 Examples of SSRIs

• Fluoxetine

  • Prozac

• Paroxetine

• Sertraline

What are SSRIs used for?

• anxiety

• Fear

• Compulsive disorders

What is safer SSRIs or TCAs?

SSRIs are safer because they have less side effects

How long must you wait after using a SSRI to use a MAOI?

2 week wait between an MAOI and a SSRI

• 5 week washout period

Can you use tramadol with SSRIs?

No. It interacts with the serotonin receptors

Are transdermal SSRIs as good as other routes?

No. Transdermal have not been proven to have consistent blood levels of the drug

What do MAOIs do?

Interfere with the breakdown of serotonin, norepinephrine, and dopamine in the cells

What is the only MAOI we use?

Selegiline (aka Anipryl)

True or False: MAOIs can be used with other neutriceuticals and pharmaceuticals, including Amitraz, St. John’s Wort, and tryptophan.

False it reacts badly with these.

What is trazodone?

An antidepressant, a serotonin agonist/antagonist (pre/post synaptic)

Can you use trazadone with SSRIs or TCAs?

Yes

What is Mirtazapine and what does it do?

• an antidepressant in humans that is seen to even out mood changes and decrease anxiety

• Increases 5-HT and NE activity; appetite stimulant in cats

How often can Mirtazapine be given in cats and dogs?

Cats: q72h

Dogs: daily

What is gabapentin used for?

Adjunct therapy for therapy and anxiety

What is combined with gabapentin for daily administration?

an SSRI or TCA