Anti-Epileptics/Respiratory Stimulants Flashcards
What makes up 10% of seizure causes in dogs?
Extracranial disorders
What extracranial disorders can cause seizures?
Electrolyte imbalances Liver disease Renal failure Toxins/ drugs Hypothyroidism (rare)
What makes up 90% of seizure causes in dogs?
CNS Disorders
Name the 2 types of CNS disorders that cause seizures
Primary epilepsies (idiopathic) Secondary epilepsies (organic brain disease - tumors, infections, trauma)
T/F Epilepsy is a life-long disorder
TRue
What is a seizure
clinical manifestation and/or hypersynchronous neuronal discharges in the brain
How do seizures present clinically
(probably dont need to know
episodic impairment or loss of conciousness accompanied by : motor abnormalities (convulsions) sensory disturbances (flashes of light) autonomic signs (urination/ defecation, salivation/vomiting)
What is epilepsy
2 or more seizures at least 24 hr apart resulting from a nontoxice/ nonmetabolic cause
What are clusters
continous seizure activity lasting longer than 30 min
2 general mechanisms of anti-epileptic agents
suppress neuronal firing in the epileptiform foci
inhibit spread of seizure into normal tissue
What are some shortcomings of AED’s?
Some animals become refractory to AED’s
lots of side effects
tolerance
loss of efficacy over time
When is an AED considered effective
when there is > 50% reduction in number of seizures during a given time frame
What are the goals of AED’s
reduce seizure frequency and severity
What is Diazepam’s method of action
activates GABA-A Cl channels which inhibits depolarization and neuronal firing
What is one great thing about diazepam
can be given rectally in an emergency if animal is seizuring
What is one bad thing about diazepam
animals develop tolerance after 1 wk of PO TID
What does Diazepam cause in cats
Idiosyncratic hepatic necrosis
Phenobarbital
acidic, long acting barbituate
classified as sedative agent
moderately protein bound
T/F Initial phenobarb dose required to treat seizures is greater than dose that causes sedation
True
How is the sedative effect of Phenobarb overcome
tolerance to sedative effect occurs within 10-14 days
What blood level increases with phenobarbital
ALP (liver enzymes)
What are some drawbacks of phenobarbital
- Animal develop dependence to drug (severe withdrawal symptoms
- Increased liver enzymes cause tolerance so dose must be increased in chronic treatment
- can cause drug interactions
What drug interacts with Phenobarb
griseofulvin
Side effects of Phenobarb
elevated liver enzymes (increase drug metabolism of many drugs) restlessness/ irritability PU/PD sedation/ataxia decrease serum T4 with normal TSH
What toxicity does phenobarb cause
Hepatotoxicity
How often should you monitor liver enzymes and check serum chemistry
every 6 months
Potassium bromide
Not controlled/ not FDA approved
actions diminished by increased CL- concentration
What type of diet must animals being treated with KBr stay on
Low salt (chloride displaces bromide)
What type of bromide should be used for a loading dose
NaBR not KBr
Is Bromide safe for cats
NO!!
What side effects do Bromide cause
Psuedohyperchloremia ( because halide) Bromism toxicity (animal looks drunk) Fatal idiosyncratic pumonary disease in CATS!!
Zonisamide
Related to sulfonamide antibiotics
metabolized by liver
Really effective and safe for CATS!!!!
how does Levetiracetam work
Inhibits synaptic vesicle protein (blocks Calcium channels to prevent neurotransmitter release)
How is levetiracetam used
Usually as an adjunctive treatment with Phenobarb
But also used because safe for cats and RABBITS!
Gabapentin
Drug of choice for RABBITS!! not effective in dogs
What 2 respiratory stimulants do we have to know?
Caffeine and Doxopram
What part of the body does Doxopram target
Medullary (brainstem)
Where does caffeine target
Cortical
T/F CNS stimulants like caffeine and doxopram stimulate multiple CNS pathways
TRUE!!!
What is Doxopram’s major actions
stimulates carotid chemoreceptors
stimulates brainstem respiratory centers
What is Doxopram ONLY used for today
stimulate laryngeal function and respiration during laryngeal exam
What is the Theophylline used for
bronchodilator
