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Table 3 Details of feline population size, seizure frequency, treatment time, doses of AED(s), seizure frequency reduction after AED initiation, 95% CI for the successful and affected cases and evidence statements for each study

From: Systematic review of antiepileptic drugs’ safety and effectiveness in feline epilepsy

References Engel et al. [20] (ELAS 1) Engel et al. [20] (ELAS 2) Engel et al. [20] (Clinical trial) Center et al. [45] Hughes et al. [46] Schwarz-Porsche & Kaiser, [44] Sawchuk et al. [47] Schwarz-Porsche & Kaiser, [44] Roye et al., [48] Schwarz-Porsche & Kaiser [44]
AED evaluated Imepitoin Diazepam Primidone Phenytoin
2nd AED -      - - - - Diazepam
3rd AED -      - - - - -
4th AED -      - - - - -
No of cats 6 6 8 (7 were evaluated for the safety profile) 11 (non-epileptic cats) 5 (non-epileptic cats) NA 11 6 4 (non-epileptic cats) 2
Age of cats at seizure onset (years) NA NA median 4; mean 6.3; range 1-15 NA range 1-12 range 0.2-9 NA range 0.2-9 NA range 0.2-9
Period of treatment or follow-up (months) 1 1 at least 2 (for the seizure-freedom cases the period was mean 4; range 2-7.5) 0.5 0.25-0.5 6 3 range 5-108 0.8 >3-9
Dose of AED(s) (mg/kg) 30 PO BID 40 & 80 PO BID median 30; mean 27.92 PO BID 1.25-2 PO SID or BID 0.23-0.82 PO SID 0.5-2 PO (divided in 3 daily doses) 20 mg/kg PO BID 40-50 PO (divided in three daily doses) 10 PO and intramuscularly SID 1.5 PO SID
Serum levels of AED(s) NA NA NA NA NA NA 4.1 μg/mL NA 25-35 μg/mL 6.5-17 μg/mL
Pre-treatment SF (seizures/month or year) NA NA Median 20; mean 57.71; range 2-200   NA NA NA NA NA NA
Post-treatment SF (seizures/month or year) NA NA Median 1.5; mean 19.43; range 0-100 NA NA NA NA NA NA NA
No of cats that were failures NA NA 3/8 (37%) NA NA - NA 2/6 (33%) NA 1/2 (50%)
No of cats with >0% - <50% reduction in SF NA NA - NA NA 20% NA - NA -
No of cats with ≥50% - <100% reduction in SF NA NA 1/8 (13%) NA NA 40% NA 2/6 (33%) NA -
No of cats with 100% reduction in SF NA NA 4/8 (50%) NA NA 40% NA 2/6 (33%) NA 1/2 (50%)
95% CI of successfully treated cases NA NA 30-86% NA NA NA NA 30-90% NA 9-90%
Prevalence of adverse effects 0 % (apart from intermittent/rare vomiting) 0 % (apart from intermittent/rare vomiting, hypersalivation and slightly decreased appetite) 5/7 (71%) NA NA 0% 11/11 (100%) 1/6 (17%) 4/4 (100%) 2/2 (100%)
95% CI of cases that developed adverse effects NA NA 36-92% NA NA 0% 100% 3-56% 100% 100%
Body system affected and adverse effects NA NA Neurological (sedation (2), ataxia (1)), GI (anorexia (2), PP (1), vomit (2), hypersalivation (1)), PD (1), decreased drinking (1) Neurological (sedation(5), ataxia(5)), GI (acute hepatic necrosis(11), anorexia (5)) GI (acute hepatic necrosis) NA Neurological (sedation, ataxia) Neurological (sedation), GI (anorexia, weight loss) Neurological (sedation, ataxia) GI (anorexia) GI (anorexia), ClinPath (increased liver enzymes)
Most common adverse effects Intermitent vomit Intermittent vomit Sedation, vomit, decreased appetite NA NA NA NA NA NA NA
Adverse effect type I I I I & II II NA I NA I I
Proportion of specific adverse effects for each AED based on all study reports Type I: sedation (1/3; 33%) and ataxia (1/3; 33%), GI signs, i.e. anorexia (1/3; 33%), PP (1/3; 33%), vomiting (1/3; 33%), hypersalivation (1/3; 33%), and PD (1/3; 33%) or decreased water consumption (1/3; 33%) Type I: sedation and ataxia Type I: sedation (2/2; 100%), ataxia (1/2; 50%), anorexia (1/2; 50%) and weight loss (1/2; 50%) Type I: anorexia (2/2; 100%), sedation (1/2; 50%), ataxia (1/2; 50%), increased liver enzymes (1/2; 50%)
Type II: acute hepatic necrosis
One study reported no adverse effects
Proportion of specific adverse effects for each AED based on the total affected population Sedation (2/19; 11%), anorexia (2/19; 11%), vomiting (2/19; 11%), ataxia (1/19; 5%), PP (1/19; 5%), hypersalivation (1/19; 5%), PD (1/19; 5%) and decreased drinking (1/19; 5%) NA Sedation (12/17; 71%), ataxia (11/17; 65%), anorexia (1/17; 6%) and weight loss (1/17; 6%) Anorexia (6/6; 100%), sedation (4/6; 67%) ataxia (4/6; 67%) and increased liver enzymes (2/6; 33%)
  Weak and good level of evidence for imepitoin’s efficacy and safety profile, respectively Weak level of evidence for diazepam’s efficacy and safety profile Weak level of evidence for primidone’s efficacy and safety profile Weak level of evidence for phenytoin’s efficacy and safety profile
  1. AED(s), anti-epileptic drug(s); BID, bis in die (twice daily); CI, confidence interval; GI, gastrointestinal; IE, idiopathic epilepsy; LEV, Levetiracetam; m, month(s); NA, Not Available; PB, phenobarbital; PD, polydipsia; PU, polyuria; PP, polyphagia; PBr, potassium bromide; PO, per os; SID, semel in die (once daily); TID, ter in die (three times daily); w, week(s); year(s); y