Effect of vigabatrin and gabapentin on phenytoin pharmacokinetics in the dog

Matar, Kamal M.; Nicholls, P. J.; Bawazir, Saleh A.; Al-Hassan, M. I.; Tekle, A.

doi:10.1006/phrs.2000.0713

Cited by 4 publications

(7 citation statements)

References 18 publications

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“…(1973) reported that the elimination half‐life of phenytoin was extremely long (more than 3 days) in cats. On the other hand, the elimination half‐life in dogs is only 2 h (Matar et al. , 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Tobin et al (1973) and Roye et al (1973) reported that the elimination half-life of phenytoin was extremely long (more than 3 days) in cats. On the other hand, the elimination half-life in dogs is only 2 h (Matar et al, 2000). The elimination of phenobarbital, which is also a CYP2C substrate becomes much faster after repeated doses because of CYP2C induction in dogs (Hojo et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

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Characterization of cytochrome P450‐mediated drug metabolism in cats

Shah

Sanda

Regmi

et al. 2007

Vet Pharm & Therapeutics

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In this study we examined activities of cytochrome P450 (CYP)1A, 2C, 2D and 3A using hepatic microsomes from five male and five female cats. CYP1A, 2C, 2D and 3A activities were referred by ethoxyresorufin O-deethylation (EROD), tolbutamide hydroxylation (TBH), bufuralol 1'-hydroxylation (BLH) and midazolam 1'- and 4-hydroxylation respectively. The anti-rat CYP1A2 and CYP3A2 serum significantly inhibited EROD and midazolam 1'- and 4-hydroxylation, suggesting that EROD and midazolam 1'- and 4-hydroxylation were catalysed by CYP1A and 3A in cats respectively. Quinidine inhibited BLH in cats microsomes at quite low concentrations, suggesting that BLH was catalysed by CYP2D in cats. Tolbutamide hydroxylation activities were negligible in hepatic microsomes from both male and female cats, suggesting CYP2C activities of cats are extremely low. This suggests that CYP2C substrates should be carefully administered to cats. Although there is no sexual difference in CYP1A activities, there are differences in CYP2D and 3A activities of cats. CYP2D activities were higher (3-fold), but CYP3A activities were lower (one-fifth) in female cats. These results might suggest that CYP2D and 3A substrates should be prescribed for male and female cats using different dosage regimen.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Characterization of cytochrome P450‐mediated drug metabolism in cats

Shah

Sanda

Regmi

et al. 2007

Vet Pharm & Therapeutics

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“…24 Unfortunately neither of these are available in Australia. Many new AEDs produce side effects in dogs: chronic administration of the GABA transaminase inhibitor vigabatrin may lead to intramyelinic oedema in dogs; 25 felbamate can give rise to blood dyscrasias and liver disease; 22 the neuronal sodium channel blocker topiramate 26 may result in gastrointestinal irritability 4 and the neuronal sodium channel blocker lamotrigine 27 is converted to a cardiotoxic metabolite in dogs. 4 Additional drugs that have been shown to be useful or potentially useful in IE and induce minimal side effects include clorazepate (a long acting diazepam pro-drug), levetiracetam (mechanism of action unknown) 24 and gabapentin.…”

Section: Discussionmentioning

confidence: 99%

“…26 It is also effective in alleviating neuropathic pain. 26 Although its exact mechanism of action in the CNS is uncertain, it may indirectly enhance GABA receptor activation or GABA synthesis 14,27 thereby increasing chloride conductance and preventing neuronal excitation. The dose rate administered here was extrapolated from other publications concerning canine IE 14 with a previous study using a dose rate of 10mg/kg/d every 8 h. 5 In dogs, its elimination half-life is 3 to 4 hours, compared to 5 to 6 hours in humans.…”

Section: Discussionmentioning

confidence: 99%

“…The dose rate administered here was extrapolated from other publications concerning canine IE 14 with a previous study using a dose rate of 10mg/kg/d every 8 h. 5 In dogs, its elimination half-life is 3 to 4 hours, compared to 5 to 6 hours in humans. 4,27 Gabapentin is well absorbed orally, with peak serum levels occurring within 2 h of dosing. 27 In people, bioavailability is inversely related to dose rate.…”

Section: Discussionmentioning

confidence: 99%

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Improving seizure control in dogs with refractory epilepsy using gabapentin as an adjunctive agent

2005

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Addition of gabapentin to phenobarbitone and/or potassium bromide increased the interictal period and shortened the post-seizure recovery in some canine epileptics. In some dogs, seizures were prevented completely, while in others there was an increase in interictal period. The short-half life of gabapentin has advantages for seizure control, however its present high cost may prohibit therapy in large dogs.

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