Peer-reviewed veterinary case report
Switching from brand to generic phenobarbital in dogs with epilepsy
By Bankstahl, Marion et al.·Published in BMC veterinary research·2013·Department of Pharmacology, Germany·View original on PubMed →
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Original publication title: Is switching from brand name to generic formulations of phenobarbital associated with loss of antiepileptic efficacy?: a pharmacokinetic study with two oral formulations (Luminal(®) vet, Phenoleptil(®)) in dogs.
- Species:
- dog
Plain-English summary
A group of healthy Beagle dogs was tested to see if switching from the brand name phenobarbital (Luminal vet) to a generic version (Phenoleptil) affected seizure control. The study found that both medications had similar levels of the drug in the dogs' blood, meaning they should work the same way for most dogs. However, one dog did show lower levels after taking the generic, which could be a concern for some pets. Overall, while most dogs should not experience issues when switching, individual responses may vary, so it's important to monitor your dog closely if a switch is made.
People also search for: dog epilepsy medication switch · phenobarbital vs Phenoleptil for dogs · why is my dog having seizures after changing medication
Abstract
BACKGROUND: In human medicine, adverse outcomes associated with switching between bioequivalent brand name and generic antiepileptic drug products is a subject of concern among clinicians. In veterinary medicine, epilepsy in dogs is usually treated with phenobarbital, either with the standard brand name formulation Luminal(®) or the veterinary products Luminal(®) vet and the generic formulation Phenoleptil(®). Luminal(®) and Luminal(®) vet are identical 100 mg tablet formulations, while Phenoleptil(®) is available in the form of 12.5 and 50 mg tablets. Following approval of Phenoleptil(®) for treatment of canine epilepsy, it was repeatedly reported by clinicians and dog owners that switching from Luminal(®) (human tablets) to Phenoleptil(®) in epileptic dogs, which were controlled by treatment with Luminal(®), induced recurrence of seizures. In the present study, we compared bioavailability of phenobarbital after single dose administration of Luminal(®) vet vs. Phenoleptil(®) with a crossover design in 8 healthy Beagle dogs. Both drugs were administered at a dose of 100 mg/dog, resulting in 8 mg/kg phenobarbital on average. RESULTS: Peak plasma concentrations (Cmax) following Luminal(®) vet vs. Phenoleptil(®) were about the same in most dogs (10.9 ± 0.92 vs. 10.5 ± 0.77 μg/ml), and only one dog showed noticeable lower concentrations after Phenoleptil(®) vs. Luminal(®) vet. Elimination half-life was about 50 h (50.3 ± 3.1 vs. 52.9 ± 2.8 h) without differences between the formulations. The relative bioavailability of the two products (Phenoleptil(®) vs. Luminal(®) vet.) was 0.98 ± 0.031, indicating that both formulations resulted in about the same bioavailability. CONCLUSIONS: Overall, the two formulations did not differ significantly with respect to pharmacokinetic parameters when mean group parameters were compared. Thus, the reasons for the anecdotal reports, if true, that switching from the brand to the generic formulation of phenobarbital may lead to recurrence of seizures are obviously not related to a generally lower bioavailability of the generic formulation, although single dogs may exhibit lower plasma levels after the generic formulation that could be clinically meaningful.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/24107313/