Neuro

Question 1

Phenobarbital

Answer 1

MOA: Barbiturate. Prolong opening time of post-synaptic Cl channels –> membrane hyperpolarization, impairing nerve impulse propagation. Also has GABA like effects.
Adv: Sedation, dose dependent respiratory depression, reduced intestinal, ureteral, uterine tone. PU/PD, polyphagia initial 2-3 weeks. Can alter thyroid function.
Other: Cats particularly sensitive to sedative effects, facial pruritus. Rarely immune mediated cytopenias.

Question 2

Levetiracetam

Answer 2

Exact MOA unknown; may selectively prevent epileptiform burst firing and propagation of seizure activity
Adv: Sedation, ataxia (D); hypersalivation (cats)

Question 3

Zonisamide

Answer 3

MOA: exact unknown; antiseizure activity at Na and T-type Ca channels - suppressing neuronal hypersynchronization. Carbonic anhydrase activity. No GABA.
Adv: Sedation, ataxia, decreased ALT; cats - vomiting, ataxia, hypersensitivity
Uncommon: Idiosyncratic hepatotoxicity, reduced TT4
Other: sulfonamide containing compound, unlikely to cause KCS, sulfa-related side effects

Question 4

Bromide

Answer 4

MOA: generalized depressant effects. Br ions compete with Cl across cell memrbanes –> membrane hyperpolarization
Adv: increased ALT/ ALP, idiosyncratic pancreatitis, hyperchloremia with negative gap; cats - pulmonary (cough, eosinophilic bronchitis)