Benzodiazepines (diazepam, lorazepam, midazolam, and clonazepam) are potent, fast-acting anticonvulsants and therefore (particularly diazepam), are the preferred initial therapy in status epilepticus (SE).

Indications
Diazepam is the drug most commonly used in veterinary medicine for the initial treatment of SE. When administered intravenously transient, high serum and brain concentrations of diazepam are achieved with 1 minute. With its relatively brief duration of action however, diazepam is not a definitive therapy for SE. Lorazepam has a longer duration of protection as brain concentrations are maintained for longer. Because SE may end spontaneously, IV diazepam should not be administered to a patient presenting in a post-ictal state unless there is another seizure.

Dose
Recommended dose is 0.5 to 1.0 mg/kg diazepam IV, up to a maximum dose of 20 mg, in dogs. This dose can be repeated to effect or twice within two hours. Constant rate intravenous infusions of diazepam have been advocated in human and veterinary patients. The recommended dose is 2-5 mg/hr in 5% dextrose in water. This takes 15-20 minutes to penetrate the CNS but has a prolonged effect. Continuous use in prolonged seizures should be avoided as a diminished response is seen with repeated administration. If the diazepam does not control the seizures, the use of phenobarbitone (5-10 mg/kg IV) should be considered.

Intravenous administration of diazepam may not be possible in some patients. It can be administered intramuscularly (IM), although absorption is not predictable. Rectal administration of diazepam may be considered initially at a dose of 0.5 to 2.0 mg/kg body weight depending upon whether the animal was being treated with phenobarbitone before the onset of SE. It may be necessary to use the higher dose in dogs receiving long-term phenobarbitone therapy. In previously untreated dogs, peak plasma concentrations of diazepam are seen 14 minutes after a per rectum dose of 1 mg/kg.

Side-effects
Adverse effects of intravenous benzodiazepines include respiratory depression, hypotension, and impaired consciousness.

References

Platt S, Randell SC, Scott KC et al (2000) Comparison of plasma benzodiazepine concentrations following intranasal and intravenous administration of diazepam in dogs. AJVR 61, 651-654. - PubMed–

Podell M (1995) The use of diazepam per rectum at home for the acute management of cluster seizures in dogs. JVIM 9, 68-74. - PubMed -

Wagner SO, Sams RA, Podell M (1998) Chronic phenobarbital therapy reduces plasma benzodiazepine concentrations after intravenous and rectal administration of diazepam in the dog. J Vet Pharmacol Therap 21, 335-341. - PubMed -