フェノバルビタール

使用用途

• Idiopathic epilepsy (initial dose)
• Idiopathic epilepsy (maintenance)
• Idiopathic epilepsy (rapid loading)
• Status epilepticus
• Emergency seizure control
• Sedation (situational distress/travel)
• Seizures
• Seizures (rapid loading)
• Enzyme induction in organochlorine toxicity
• Seizures (Adults)
• Seizures (Adults)
• Seizures (Foals)
• Seizures (Foals)
• Idiopathic epilepsy (initial dose)

投与方法

考えられる副作用

• Dogs: Transient anxiety, agitation, or lethargy upon initiation
• Dogs: Polydipsia (PD), polyuria (PU), and polyphagia (PP)
• Dogs: Sedation and ataxia (especially at higher serum levels)
• Dogs: Elevated liver enzymes (ALT, ALP) - common and not always indicative of failure
• Dogs: Hepatotoxicity (uncommon, usually at levels >30-40 mcg/mL)
• Dogs: Rare blood dyscrasias (anemia, thrombocytopenia, neutropenia)
• Dogs: Rare superficial necrolytic dermatitis (SND)
• Cats: Ataxia, persistent sedation, lethargy
• Cats: Polyphagia, weight gain, PU/PD
• Cats: Rare immune-mediated reactions and bone marrow hypoplasia
• Cats: Coagulopathies (at very high doses)
• Sedation

注意事項と禁忌

• Known hypersensitivity to barbiturates
• Severe liver disease
• Nephritis (large doses)
• Severe respiratory depression
• Hepatic dysfunction
• Severe renal impairment
• Hypersensitivity to barbiturates
• > **Intravenous Administration**: Must be given SLOWLY (not more than 60 mg/minute). Too rapid IV administration may cause profound respiratory depression. > **Tissue Irritation**: Do NOT administer subcutaneously (SC) or perivascularly. The injectable solution is highly alkaline and very irritating, potentially causing significant tissue necrosis. * **Patient Conditions**: Use with extreme caution in patients that are hypovolemic, anemic, have borderline hypoadrenal function, or have pre-existing cardiac or respiratory disease. * **Feline Sensitivity**: Cats are particularly sensitive to the respiratory depressant effects of barbiturates. * **Hepatic Function**: Chronic administration induces hepatic microsomal enzymes. Monitor liver function closely, especially in dogs, as hepatotoxicity can occur at high serum concentrations. * **Endocrine Testing**: Can alter thyroid testing (decreased T4, normal T3, normal/increased TSH) and may cause a false positive low-dose dexamethasone suppression test.

薬物相互作用

• Acetaminophen: Increased risk for hepatotoxicity, particularly with large or chronic doses of barbiturates.
• Carprofen: Increased risk for hepatotoxicity secondary to carprofen metabolites.
• MAO Inhibitors (e.g., Selegiline): May prolong phenobarbital effects.
• Phenytoin: Barbiturates may affect phenytoin metabolism, and phenytoin may alter barbiturate levels.
• Rifampin: May induce enzymes that increase the metabolism of barbiturates.
• Levetiracetam: Phenobarbital reduces levetiracetam elimination half-life by about 50% in dogs.
• Warfarin: Phenobarbital may decrease anticoagulant effects by lowering serum concentrations.
• Corticosteroids: Phenobarbital increases the metabolism and clearance of corticosteroids, potentially reducing their efficacy.
• Doxycycline: Phenobarbital decreases doxycycline serum concentrations; effect may persist for weeks after discontinuation.
• Theophylline: Phenobarbital increases theophylline metabolism, lowering its serum concentrations.

よくある質問