ํ๋ ธ๋ฐ๋ฅด๋นํ
**ํ๋ ธ๋ฐ๋ฅด๋นํ(Phenobarbital)**์ ์ฅ๊ธฐ ์์ฉ ๋ฐ๋ฅด๋นํฌ๋ฅด์ฐ๊ณ ์ฝ๋ฌผ๋ก, ์์ํ์์ ๋ฐ์ ์ฅ์ ๊ด๋ฆฌ์ ์ด์ ์ญํ ์ ํฉ๋๋ค. * **์ฃผ์ ์ฉ๋**: ๊ณ ์์ด์ ํน๋ฐ์ฑ ๊ฐ์ง ์น๋ฃ์ ์์ด ์ต์ฐ์ ์ ํ์ฝ์ผ๋ก ๋๋ฆฌ ๊ฐ์ฃผ๋๋ฉฐ, ๊ฐ์ ๋ง์์๋ ๊ฐ์ฅ ํํ๊ณ ํจ๊ณผ์ ์ธ 1์ฐจ ๋๋ ๋ณด์กฐ ํญ๊ฒฝ๋ จ์ ์ค ํ๋์ ๋๋ค. * **์์์ ์ฅ์ **: ์ ๋ฆฌํ ์ฝ๋ํ์ ํ๋กํ์ผ, ์๋์ ์ธ ์์ ์ฑ, ์ ์ฆ๋ ํจ๋ฅ ๋ฐ ์ ๋ ดํ ๋น์ฉ์ ์ ๊ณตํฉ๋๋ค. ์ต๋ฉด ์ดํ์ ์ฉ๋์์๋ ๋ฐ์์ ํจ๊ณผ์ ์ผ๋ก ์กฐ์ ํ ์ ์์ต๋๋ค. * **๊ฐ ์๊ฐ์ ๋**: ํ๋ ธ๋ฐ๋ฅด๋นํ์ ๋ ํนํ ์ฝ๋ฆฌํ์ ํน์ง์ ๊ฐ์ ์ฌ์ดํ ํฌ๋กฌ P450 ํจ์๋ฅผ ์ ๋ํ๋ ๋ฅ๋ ฅ์ ๋๋ค. ์๊ฐ์ด ์ง๋จ์ ๋ฐ๋ผ ํ์์ ๊ฐ์ ์ฝ๋ฌผ์ ๋ ํจ์จ์ ์ผ๋ก ๋์ฌํ๊ฒ ๋๋ฉฐ, ์ด๋ก ์ธํด ์น๋ฃ ํ์ฒญ ๋๋๋ฅผ ์ ์งํ๊ธฐ ์ํด ์ข ์ข ์ฉ๋ ์ฆ๊ฐ๊ฐ ํ์ํฉ๋๋ค. * **๊ธฐํ ์ฉ๋**: ๋ฐ์ ์กฐ์ ์ธ์๋ ๊ฒฝ๊ตฌ์ฉ ์ง์ ์ (์: ๊ณ ์์ด์ ์ฌํ ๋ถ์ ๋๋ ๊ณผ๋ํ ๋ฐ์ฑ)๋ก ๊ฐํน ์ฌ์ฉ๋๋ฉฐ, ๋ฒค์กฐ๋์์ ํ์ผ๋ก ์ด๊ธฐ ์กฐ์ ์ ํ ํ์ ๊ฐ์ง ์ค์ฒฉ์ฆ ๊ด๋ฆฌ์๋ ์ฌ์ฉ๋ฉ๋๋ค.
์์ฉ ๊ธฐ์ : Phenobarbital exerts its antiseizure and sedative effects through multiple mechanisms within the central nervous system: * **GABA-A Receptor Modulation**: Phenobarbital binds to the allosteric barbiturate site on the **GABA-A receptor**. Unlike benzodiazepines (which increase the *frequency* of chloride channel opening), phenobarbital increases the **duration** of chloride channel opening โ enhanced influx of chloride ions โ hyperpolarization of the postsynaptic neuronal membrane โ increased seizure threshold and decreased spread of seizure activity. * **Glutamate Inhibition**: It inhibits the release of excitatory neurotransmitters, specifically **glutamate**, thereby dampening CNS excitability. * **Calcium Channel Blockade**: At high (anesthetic) doses, it inhibits the uptake of calcium at nerve endings, further reducing neurotransmitter release. * **Other Neurotransmitters**: It has also been shown to inhibit the release of acetylcholine and norepinephrine.
๋๋ฌผ ์ข ๋ณ ์ฉ๋
- Idiopathic epilepsy (initial dose) ยท 2-2.5 mg/kg ยท PO ยท q12h ยท Optimum therapeutic levels 23-30 mcg/mL.
- Idiopathic epilepsy (maintenance) ยท 1-2 mg/kg ยท PO ยท q12h ยท Adjust based on serum levels.
- Idiopathic epilepsy (rapid loading) ยท 16-20 mg/kg once IV loading dose, then 1-5 mg/kg PO q12h ยท IV/PO ยท Once then q12h
- Status epilepticus ยท 2-5 mg/kg bolus (repeat at 20 min intervals up to 2x), or add to diazepam infusion at 2-10 mg/hour ยท IV ยท PRN ยท If seizures persist after diazepam therapy.
- Emergency seizure control ยท 3 mg/kg (repeat q20m up to 24 mg/kg/24h) OR 10 mg/kg bolus ยท IV ยท PRN ยท Given along with IV diazepam.
- Sedation (situational distress/travel) ยท 2-3 mg/kg ยท PO ยท PRN ยท For controlling excessive vocalization.
- Seizures ยท 1-2 mg/kg ยท PO ยท q8-12h (2-3 times daily)
- Seizures (rapid loading) ยท Loading dose of 16-20 mg/kg once IV; maintenance dose of 1-2 mg/kg PO q8-12h ยท IV/PO ยท q8-12h
- Enzyme induction in organochlorine toxicity ยท 5 grams ยท PO ยท Daily ยท 3-4 weeks on, 3-4 weeks off, repeat
ํฌ์ฌ ๊ฒฝ๋ก
๊ธ๊ธฐ
- Known hypersensitivity to barbiturates
- Severe liver disease
- Nephritis (large doses)
- Severe respiratory depression
- Hepatic dysfunction
- Severe renal impairment
- Hypersensitivity to barbiturates
์ด์๋ฐ์
- 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
- Ataxia
- Polyuria (PU)
- Polydipsia (PD)
์ฝ๋ฌผ ์ํธ์์ฉ
- Acetaminophen ยท Increased risk for hepatotoxicity, particularly with large or chronic doses of barbiturates.
- Carprofen ยท Increased risk for hepatotoxicity secondary to carprofen metabolites.
- MAO Inhibitors (e.g., Selegiline) ยท May prolong phenobarbital effects.
- Phenytoin ยท Barbiturates may affect phenytoin metabolism, and phenytoin may alter barbiturate levels.
- Rifampin ยท May induce enzymes that increase the metabolism of barbiturates.
- Levetiracetam ยท Phenobarbital reduces levetiracetam elimination half-life by about 50% in dogs.
- Warfarin ยท Phenobarbital may decrease anticoagulant effects by lowering serum concentrations.
- Corticosteroids ยท Phenobarbital increases the metabolism and clearance of corticosteroids, potentially reducing their efficacy. ยท moderate
- Doxycycline ยท Phenobarbital decreases doxycycline serum concentrations; effect may persist for weeks after discontinuation.
- Theophylline ยท Phenobarbital increases theophylline metabolism, lowering its serum concentrations.
- Chloramphenicol ยท May increase the effects of phenobarbital while phenobarbital may decrease chloramphenicol levels. ยท major
- Levothyroxine ยท Increased hepatic metabolism and clearance of T4 ยท moderate
๋ชจ๋ํฐ๋ง
- Anticonvulsant efficacy (seizure frequency and severity)
- Adverse effects (CNS depression, ataxia, PU/PD, weight gain)
- Serum phenobarbital levels (Dogs: 20-35 mcg/mL; Cats: 23-30 mcg/mL). Wait 5-6 half-lives (12-14 days in dogs, 9-10 days in cats) before measuring steady-state levels.
- Routine CBC, liver enzymes (especially ALT and AST), and bilirubin at least every 6 months during chronic therapy.
- Serum phenobarbital concentrations (trough levels)
- Liver enzymes (ALT, ALP, GGT)
- Serum bile acids
- Complete Blood Count (CBC)
- Renal function
๊ณผ์ฉ๋
**Clinical Signs of Toxicity**: * **Dogs**: Ataxia, lethargy, sedation, recumbency, depression, hypothermia, and coma. * **Cats**: Ataxia, sedation, and recumbency. **Treatment**: * **Decontamination**: Removal of ingested product from the gut if recent. **Activated charcoal** is highly effective and acts as a 'sink' to draw the drug from the vasculature back into the gut, enhancing clearance even if the drug was given parenterally. * **Supportive Care**: Provide intensive respiratory and cardiovascular support. * **Enhanced Elimination**: Forced alkaline diuresis can substantially augment elimination in patients with normal renal function. Peritoneal dialysis or hemodialysis may be helpful in severe intoxications or anuric patients.
VetSheet ์ฝ๋ฌผ ๋ ํผ๋ฐ์ค๋ ๋ฉดํ ์์ ์ ๋ฌธ๊ฐ๋ฅผ ์ํ ์์ ์์ฌ๊ฒฐ์ ๋ณด์กฐ ๋๊ตฌ์ด๋ฉฐ, ์ ๋ฌธ์ ํ๋จ์ด๋ ์ ์กฐ์ฌ์ ์ต์ ๋ผ๋ฒจ์ ๋์ ํ์ง ์์ต๋๋ค.