CNS Flashcards
contains material emphasized in class.
what is primary type of action potential transmission in CNS, chemical or electrical transmission
chemical
influx of which ion into the presynaptic membrane stimulates NT exocytosis
calcium ion (Ca2+)
is changing the concentration of. NT OR up/downregulating a receptor a direct or indirect receptor interaction
indirect
are CNS drugs generally extremely selective for their target
no, they are RELATIVELY selective for their target
are both initial and delayed responses important for ultimate clinical effect
yes
the ability of a drug to penetrate the lipophilic BBB is critical to its activity in the CNS. what is often involved in the BBB penetration?
active metabolites (which may have a longer half-life than the parent drug)
what are the 5 classes of drugs that affect the CNS
anesthetics, analgesics, tranquilizers and sedatives, anti-depressants and anti-anxiety drugs, anti-epileptic drugs
what is the goal of anti-epileptic therapy
balance reduction of seizures with quality of life for patient
what is a major inhibitory NT in CNS
GABA
this first-line AED is moderately lipophilic (can cross BBB), has kinetics change in first few days, and there is considerable variation in serum concentration for any specific dose
phenobarbital
name 3 adverse effects of phenobarbital
behaviour changes (sedation or hyper excitability), immune mediated anemia/neutropenia, acute hepatotoxicity, polydipsia, polyphasic, hepatotoxicity, decreased serum T4 concentrations
what should you know about drugs that inhibit cytochrome P450 enzymes, eg. chloramphenicol, cimetidine, ketoconazole
can cause phenobarbital toxicity
what does the induction of cytochromeP450 enzymes by phenobarbital change
change the PK of some other drugs
why is therapeutic drug monitoring of phenobarbital important
serum concentrations at a given dose vary between individuals, so dose adjustments often needed
when should you monitor concentration of phenobarbital in patients
monitor concentration to first steady state concentration time point (2 weeks), again at first steady state clearance time point (6 weeks), monitor liver function every 6 months
this AED has an extremely long half life (15 days dog, 10 days cat) so is very slow to reach steady state, and no peak or trough. It is cleared really (no hepatic or protein binding) so patients with kidney disease may need dose reduction
KBr potassium bromide
when is steady state reached in KBr? when should serum drug concentrations be monitored?
3 months. monitor at 1 month, 3 months, annually (or sooner if evidence of toxicity or ineffectiveness)
this AED is primarily an add-on treatment and has a short half-life
levetiracetam
this benzodiazepine AED is used to treat acute seizures and status epileptics and impractical for long-term therapy in dogs due to short half-life, tolerance/dependance possibility, and abuse potential
diazepam
dog is emergency seizuring! what is the preferred emergency seizure drug and why? what is route of administration?
diazepam, it is more lipophilic that other benzodiazepines. can give per rectum (owner can use this route), orally, or IV, but not IM
this AED has a short half-life in dogs (2 hours) so no accumulation with typical chronic use, high therapeutic index, and no therapeutic monitoring is needed
imepitoin
potential behavioural consequence of behaviour modifying drugs
aggression
behaviour modifying drugs and antidepressants take how long to exert full effects?
several weeks
is it necessary to taper behaviour modifying drugs after long-term administration
yes
