Phenoleptil
Active substance
ATC code
Species
Dog.
Indications
Prevention of seizures due to generalised epilepsy in dogs.
Dose to be administered and administration route
Administration route
For oral administration.
Amounts to be administered
The recommended initial dosage is 2.5 mg phenobarbital per kg body weight twice daily. The crossed score line on one side of the tablet allows division into two (each part of 12.5 mg phenobarbital) or four (each part of 6.25 mg phenobarbital) equal parts.
Tablets must be given at the same time each day to achieve successful therapy.
Eventual adjustments of this dosage should be made on the basis of clinical efficacy, blood levels and the occurrence of undesirable side effects. The required dosage will differ to some extent between individuals and with the nature and severity of the disorder. Also see under section 4.5i).
The serum phenobarbital concentrations should be measured after steady state has been achieved. Blood samples could be taken at the same time to allow plasma phenobarbital concentration to be determined preferably during trough levels, shortly before the next dose of phenobarbital is due. The ideal therapeutic range for serum phenobarbital concentration is between 15 and 40 µg/ml. If serum phenobarbital concentration is less than 15 µg/ml or the seizures are not controlled the dose may be increased by 20% at a time, with associated monitoring of serum phenobarbital levels up to a maximum serum concentration 45 µg/ml. The ultimate doses may vary considerably (ranging from 1 mg to 15 mg per kg body weight twice daily) because of the differences in phenobarbital excretion and differences in sensitivity among patients.
If the seizures are not being satisfactorily controlled and if the maximum level concentration is about 40 µg/ml, then the diagnosis should be reconsidered and/or a second antiepileptic product (such as bromides) should be added to the treatment protocol.
In stabilised epileptic patients, it is not recommended to switch from other phenobarbital formulations to Phenoleptil Tablets. However, if this can not be avoided then additional caution should be taken. It is recommended to try to achieve as similar dosages as possible compared with the previous formulation used taking into consideration current plasma concentration measurements. Stabilisation protocols as for initiating treatments should be followed. Also see section 4.5i).
Adverse reactions
During start of therapy ataxia, sleepiness, lethargy and dizziness can very rarely occur but these effects are usually transitory and disappear in most, but not all, patients with continued medication.
Some animals can very rarely demonstrate a paradoxical hyperexcitability, particularly after first starting therapy.
As this hyperexcitability is not linked to overdosage, no reduction of dosage is needed.
Polyuria, polydipsia and polyphagia can very rarely occur at average or higher therapeutic active serum concentrations; these effects can be diminished by limiting intake of both food and water.
Sedation and ataxia often become significant concerns (occurring very rarely) as serum levels reach the higher ends of the therapeutic range.
High plasma concentrations may be associated with hepatotoxicity (very rare).
Phenobarbital can have deleterious effects on stem cells from bone marrow.
Consequences are immunotoxic pancytopenia and/or neutropenia (very rare). These reactions disappear after the treatment’s withdrawal.
Treating dogs with phenobarbital may lower their TT4 or FT4 serum levels, however this may not be an indication of hypothyroidism. Treatment with thyroid hormone replacement should only be started if there are clinical signs of the disease.
If adverse effects are severe, a decrease in the administered dose is recommended.
The frequency of adverse reactions is defined using the following convention:
- very common (more than 1 in 10 animals displaying adverse reaction(s) during the course of one treatment)
- common (more than 1 but less than 10 animals in 100 animals)
- uncommon (more than 1 but less than 10 animals in 1,000 animals)
- rare (more than 1 but less than 10 animals in 10,000 animals)
- very rare (less than 1 animal in 10,000 animals, including isolated reports).
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| Art. Nr. | 50406/4025 |
| EAN | 3858888795658 |
