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38 Cards in this Set
- Front
- Back
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• Primidone is metabolized by the liver to? what are all three?
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phenyl-ethyl-malon-amide (PEMA) and Phenobarbital. All three are anticonvulsants.
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What is Gabapentin? Does it affect GABA? may inhibit what?
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• Gabapentin is a structural analog of GABA. However, it does not interact with GABA receptors and is not a GABA agonist, nor does it affect GABA uptake or degradation. May inhibit voltage dependent Ca and Na channels, this inhibiting excitatory NT release.
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• Gabapentin is mostly is excreted by ?
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renal mechanism and does not rely on hepatic biotransformation. Can be used in hepatic diseases.
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• Barbiturates and benzodiazepines which enhance Cl conductance may act in with KBr
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:)
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Why is Kbr not good in cats?
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• KBr is not recommended in cats because it evokes severe asthma in this species
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Barbiturate drugs? (3)
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(phenobarb, primidone, pentobarb)
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Anticonvulsant drugs?
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Pheytoin, Valoproic acid, Benzodiaz, Gabapentin
phenobarb, pentobarb, primidone |
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. stabilize neuronal membr→
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increase seizure thrshld
increase GABA→ increase Cl- |
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Act directly on ion channs→
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hyperpolarize
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decreasing Ca into nerve cells
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reduce NT release
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purpose of anticonvulsants
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To limit either initialization or spread of seizure focus in CNS
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Adverse effects of anticonvulsants
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1. Withdrawal symptoms
2. a. drugs that decrease seiz. Threshold →phenothiazine tranquilizers= ace b. antiparasitic drugs →pyrantel, levamisole, = neostigmine c. increase GI motility→ Metoclopramide 3. Enzyme Induction →BARBITUATES increase Cytochrome P450 enz of liver 4. Hepatotoxicity→ increase Blood work 5. increase Liver enz’s→ Δ dose, could increase metabolism of other drugs |
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drugs that decrese the seizure threshold:
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phenothiazine tranquilizers (ace)
antiparasitic (neostigmine) metoclopramide (increase GI motlility) |
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Phenobarb is the number one choice for?
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seizure treatment in dogs and cats
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describe phenobarb
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An oxybarbiturate; anticonv effects achieved at lower dose
increase TH, decrease TSH |
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side effects for phenobarb
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Side effects are- sedation, polyphagia, polyuria, polydipsia (PU/PD). Can enhance its own metabolism. Hepatotoxicity
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Primidone is metabolized by the liver into what?
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Metab by liver to PEMA & phenobarb
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of phenobarb and primidone.. which one is oxybarbituate.. which one is deoxybarbituate
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primidone-deoxybarbituate
phenobarb-oxybarbituate |
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can primidone be used in cats?
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no! long half life and metabolism to phenobarb is slow
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what are adverse effects to long term primidone use..
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albumin decrease and increase in liver enzymes
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phenytoin is used in human medicine but sometimes in which animal?
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horses for muscle disorders or as an antiarrhythmic
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Valproic acid is a derivative of what?
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carboxylic acid
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adverse effects of valproic acid
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hepatotoxicity and liver failure
skin disease -alopecia rash etc. |
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what kind of tablet is valproic acid
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timed release =short half life
appropriate for longterm use |
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How do you dose Felbamate
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increase gradually until you reach effective dose level.
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How does Felbamate work? is it expensive
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yes~! last resort drug
*decrease NMDA, increase GABA action *Inhibits voltage-dependent Na & Ca Channels |
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How does Gabapentin affect GABA receptors?
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Analog of GABA, does NOT interact w/ GABA rec’s, NOT GABA agonist, does NOT affect GABA uptake/degradation
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what two drugs are used as a last resort if anticonvulsants are not working
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Gabapentin and Felbamate
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how is gabapentin excreted
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through renal excretion
biotransformation in dog to N-methyl-gabapentin. CAN be used in HEPATIC dz cases & used for neuropathetic pain |
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which drugs are not hepatotoxic?
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zonisamide
gabapentin levetiracetam |
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how is levetiracetam excreted?
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urine
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levetiracetam has an effect on ca?
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yes, decrease neuronal excitability via modulation of Ca
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does liver disease affect levetiracetam
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no
Liver dz does NOT affect pharmacokinetics. Well tolerated in dogs *No depressant or anesthetic effect* |
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what are adverse reactions to levetiracetam
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Behavior change, drowsiness, GI vomiting & anorexia.
Withdrawal seizures can occur |
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does zonisamide affect ca?
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yes! MOA is by inhibition of voltage dependent Na & Ca
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how is zonisamide excreted?
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in urine as parent drug
20% metab by liver by N-acetylation (deficient in dog) & glucuronidation (deficient in cats) |
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how does potassium bromide work?
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Br enter neurons via Cl channels→ Hyperpolariz. Of neuronal membrane
*barbit & benzodiazs →enhance Cl= may act in synergy w/ Br **Treat Canine epilepticus that have not responded to phenobarb alone |
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what are adverse effects of potassium bromide?
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ADR: PP, behavior Δ, bromism,
Toxic effects: CNS depression, weakness, ataxia, proprioception GI Effects: Stomach irritation, nausea, vomiting, anorexia, constipation, PU/PD/PP, lethargy, irritability, aimless walking |
