プリミドン

使用用途

• Seizure control
• Seizure control
• Seizure control

投与方法

考えられる副作用

• Anxiety and agitation (especially during initiation)
• Elevated liver enzymes (ALT, ALP, GLDH)
• Decreased serum albumin
• Hepatic lipidosis
• Hepatocellular hypertrophy and necrosis
• Extramedullary hematopoiesis
• Depression and sedation
• Ataxia
• Polydipsia (PD)
• Polyuria (PU)
• Polyphagia
• Anorexia
• Tachycardia
• Dermatitis
• Episodic hyperventilation
• Urolith formation (primidone uroliths reported)
• Megaloblastic anemia (rare)

注意事項と禁忌

• Severe liver disease
• Demonstrated previous hypersensitivity to primidone or barbiturates
• Nephritis (large doses contraindicated)
• Severe respiratory dysfunction (large doses contraindicated)
• Cats (considered contraindicated by many clinicians due to high toxicity risk)
• **Species Warnings:** Use with extreme caution, if at all, in cats. Primidone is considered highly toxic to felines. **Patient Conditions:** Use cautiously in patients who are hypovolemic, anemic, have borderline hypoadrenal function, or have cardiac or respiratory disease. **Drug Transition:** When converting dogs from primidone to phenobarbital, it is suggested to do this slowly (tapering 1/4 of the dose each month) to prevent withdrawal seizures. **Laboratory Interference:** Barbiturates may cause falsely elevated bromosulfophthalein (BSP) retention. Primidone/phenobarbital can alter thyroid testing (decreased total and free T4, normal T3, normal/increased TSH); wait at least 4 weeks after discontinuation to perform thyroid testing. 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.
• Carbonic Anhydrase Inhibitors (e.g., acetazolamide): Oral administration may decrease the GI absorption of primidone.
• Monoamine Oxidase Inhibitors (e.g., amitraz, selegiline): May prolong phenobarbital effects.
• Phenytoin: Barbiturates may affect phenytoin metabolism, and phenytoin may alter barbiturate levels; therapeutic monitoring indicated.
• Rifampin: May induce enzymes that increase the metabolism of barbiturates.
• Antihistamines: May increase the CNS depressant effects of phenobarbital.
• Chloramphenicol: May increase the effects of phenobarbital; phenobarbital may also decrease chloramphenicol levels.
• Opiates: May increase the CNS depressant effects of phenobarbital.
• Phenothiazines: May increase the effects of phenobarbital; phenobarbital may decrease phenothiazine serum concentrations.
• Valproic Acid: May increase the effects of phenobarbital.
• Warfarin: Phenobarbital may decrease anticoagulant effects by lowering serum concentrations.
• Beta-blockers: Phenobarbital may decrease effects by lowering serum concentrations.
• Corticosteroids: Phenobarbital may decrease effects by lowering serum concentrations.
• Cyclosporine: Phenobarbital may decrease effects by lowering serum concentrations.
• Doxycycline: Phenobarbital may decrease effects by lowering serum concentrations (effect may persist for weeks after barbiturate is discontinued).
• Theophylline: Phenobarbital may decrease effects by lowering serum concentrations.

よくある質問