Soliphen

5 x 12 pc

Tablet

Active substance

Phenobarbital : 15 mg

ATC code

QN03AA02 Phenobarbital

QN03AA Barbiturates and derivatives

QN03A Antiepileptics

QN03 Antiepileptics

QN Nervous system

Species

Dogs (weighing at least 3 kg).

Indications

Prevention of seizures due to generalised epilepsy.

Dose to be administered and administration route

Oral use.

For the decision to start antiepileptic drug therapy, see section 4.4.

The required dosage will differ to some extent between individuals and with the nature and severity of the disorder.

Dogs should be dosed orally, starting with a dose of 2-5 mg per kg bodyweight per day. The dose should be divided and administered twice daily. The tablet can be divided into two equal parts to provide 7.5 mg doses.

Tablets must be given at the same time each day to achieve successful therapy.

Steady state serum concentrations are not reached until 1-2 weeks after treatment is initiated. The full effect of the medication does not appear for two weeks and doses should not be increased during this time.

Any adjustments to the starting dose are best made on the basis of clinical efficacy, blood concentrations of phenobarbital and the occurrence of undesired effects.

Due to differences in the excretion of phenobarbital and differences in sensitivity the final effective doses may vary considerably between patients (from 1 mg to 15 mg/kg body weight twice a day).

If seizures are not being controlled, the dosage may be increased by 20% at a time, with associated monitoring of serum phenobarbital levels. The phenobarbital serum concentration may be checked after steady state has been achieved, and if it is less than 15 µg/ml the dose may be adjusted accordingly. If seizures recur the dose may be raised up to a maximum serum concentration of 45 µg/ml. High plasma concentrations may be associated with hepatotoxicity.

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.

If the seizures are not being satisfactorily prevented 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.

Plasma concentrations should be interpreted in conjunction with the observed response to therapy and a full clinical assessment including monitoring for evidence of toxic effects in each animal.

Adverse reactions

Dogs :

Rare

(1 to 10 animals / 10 000 animals treated) :

Diarrhoea, emesis

Ataxia1,2,3

Very rare

(<1 animal / 10 000 animals treated, including isolated reports):

Polyphagia ¹, polydipsia¹

Polyuria¹

Sedation1,2,3

Hyperexcitability (paradoxical)^2,4

Pancytopenia⁵ (immunotoxic), neutropenia⁵

Hepatic toxicosis⁶

Low thyroxine (T4)⁷, Low free thyroxine (FT4)⁷

1effects usually transitory, which disappear with continued medication in most patients.

²at the start of therapy.

³become significant concerns as serum levels reach the higher ends of the therapeutic range.

⁴not linked to overdosage, so no reduction of dosage is needed.

⁵can result from deleterious effects of phenobarbital on bone marrow stem cells.

Disappear after the treatment’s withdrawal.

⁶may be due to high plasma concentrations.

⁷This 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.

Toxicity may develop at doses over 20 mg/kg/day or when serum phenobarbital levels rise above 45µg/ml.

Reporting adverse events is important. It allows continuous safety monitoring of a veterinary medicinal product. Reports should be sent, preferably via a veterinarian, to either the marketing authorisation holder or its local representative or the national competent authority via the national reporting system. See the package leaflet for respective contact details.