레보티록신 나트륨
Levothyroxine Sodium
3,5,3',5'-tetra-iodo-L-thyronine sodium
다른 이름: Soloxine · Synthroid · Levosyn · Thyro-Tabs · Thyrosyn · Leventa · Thyro-L · Levothroid · Levoxyl · Tirosint · T4 thyroxine sodium · levothyroxin natrium · levothyroxinum natricum · L-thyroxine sodium · tirossina · tiroxina sodica
VetSheet 수의사 팀 검수업데이트 2026년 4월 5일근거 기반 수의학 참고자료
용량은 수의사 전문가를 위한 임상 참고자료입니다. 반드시 최신 약물 정보 및 개별 환자에 따라 확인하시기 바랍니다.
동물 종별 용량
🌎 NA — North America🌍 EU — Europe
개
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Hypothyroidism | 20 micrograms/kg (0.02 mg/kg) body weight PO twice daily with a maximum dose of 0.8 mg twice daily | PO | q12h | — | 🌎 NA |
| Hypothyroidism | 10-22 micrograms/kg q12h or q24h | PO | q12h or q24h | — | 🌎 NA |
| Hypothyroidism | 0.02 mg/kg PO twice daily to start; (0.02-0.04 mg/kg PO once daily or, if necessary divided twice daily to maintain). Alternatively, give 0.5 mg/m2 | PO | q12h or q24h | — | 🌎 NA |
| Myxedema coma | 5 micrograms/kg IV q12h initially | IV | q12h | — | 🌎 NA |
- Hypothyroidism: Evaluate clinical response 4-8 weeks later and draw a T4 level 4-6 hours post dosing.
- Hypothyroidism: Maximum of 0.8 mg q12h. Reevaluate 1-2 months after initiating therapy.
- Hypothyroidism: 0.5 mg/m2 dosing may prevent hyperthyroid effects, particularly in large breed dogs.
- Myxedema coma: Oral administration may be poorly absorbed in this state.
고양이
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Hypothyroidism | 0.05-0.1 mg per cat PO once daily | PO | q24h | — | 🌎 NA |
| Post thyroidectomy | 0.1-0.2 mg (total dose) PO once daily beginning 24-48 hours post-op | PO | q24h | Several weeks or months | 🌎 NA |
- Hypothyroidism: Wait a minimum of 4-6 weeks to assess clinical response.
- Post thyroidectomy: Monitor T4 levels to determine when supplementation can be ceased.
새
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Hypothyroidism | One 0.1 mg tablet in 30 mL-120 mL of water daily | PO | q24h | — | 🌎 NA |
- Hypothyroidism: Stir water and offer for 15 minutes and remove. Use high dose for budgerigars and low dose for water drinkers.
파충류
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Hypothyroidism in tortoises | 0.02 mg/kg PO every other day | PO | q48h | — | 🌎 NA |
말
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Hypothyroidism | 10 mg in 70 mL of corn syrup once daily | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of equine metabolic syndrome | 0.1 mg/kg PO once daily, initiate treatment at 48 mg/day... and then increase to 72 mg/day after 3 months if the horse remains obese | PO | q24h | 6 months | 🌎 NA |
- Hypothyroidism: Monitor T4 levels one week after initiation of therapy.
- Adjunctive treatment of equine metabolic syndrome: Taper off by administering 24 mg/day for 2 weeks and then 12 mg/day for 2 weeks.
용량은 수의사 전문가를 위한 임상 참고자료입니다. 반드시 최신 약물 정보 및 개별 환자에 따라 확인하시기 바랍니다.
개요
레보티록신 나트륨은 갑상선에서 분비되는 내인성 호르몬인 티록신(T4)의 합성 좌선성 이성질체입니다. 수의학에서 갑상선 호르몬 대체 요법의 표준 치료제(gold standard)로 간주되며, 주로 반려견의 갑상선 기능 저하증 치료에 사용되고 때때로 다른 종에도 사용됩니다.
핵심 임상 정보:
- 전구호르몬 특성: T4는 주로 전구호르몬으로 작용하며 말초 조직에서 생물학적 활성이 더 높은 T3로 전환됩니다.
- 생체이용률: 경구 흡수율은 개체마다 차이가 클 수 있으며 음식의 영향을 받을 수 있습니다. 일관된 흡수를 위해 공복 투여가 권장되는 경우가 많습니다.
- 치료 모니터링: 개체 간 약동학적 다양성 때문에 개별 환자에게 용량을 맞추기 위해 혈청 총 T4(TT4)의 치료 약물 모니터링(TDM)이 필수적입니다.
작용 기전
Thyroid hormones regulate multiple metabolic processes, including fat, protein, and carbohydrate metabolism, and are critical for normal growth, development, and basal metabolic rate.
- Pathway: Exogenous levothyroxine (T4) is absorbed and distributed to peripheral tissues.
- Conversion: Inside cells, T4 is enzymatically deiodinated by 5'-deiodinase to triiodothyronine (T3), the primary active hormone.
- Receptor Binding: T3 enters the nucleus and binds to thyroid hormone receptors (TRs).
- Gene Transcription: The TR-T3 complex binds to thyroid response elements (TREs) on DNA → alters gene transcription → increases mRNA synthesis → increases protein synthesis, oxygen consumption, heart rate, and cellular metabolism.
안전성·주의사항
금기사항
- Acute myocardial infarction
- Thyrotoxicosis
- Untreated adrenal insufficiency
부작용
- Tachycardia
- Polyphagia
- Polyuria/Polydipsia (PU/PD)
- Excitability
- Nervousness
- Excessive panting
- Apathy or listlessness (seen in some cats)
주의
Use with caution and at a lower initial dosage in patients with concurrent hypoadrenocorticism (treated), cardiac disease, diabetes, or in elderly patients. High fiber diets may reduce absorption. Hypothyroid dogs can have decreased GFR; restoration to a euthyroid state can increase GFR and reduce serum creatinine levels. Numerous drugs can affect thyroid function tests (T4, T3, TSH), so evaluate lab results accordingly.
약물 상호작용
May decrease the metabolism of T4 to T3
May reduce levothyroxine absorption; separate doses by 4 hours
Increased risk for CNS stimulation and cardiac arrhythmias
Levothyroxine may increase requirements for insulin or oral agents
May reduce levothyroxine absorption; separate doses by 4 hours
Decreased conversion of T4 to T3
Potential for reduced digoxin levels
May reduce levothyroxine absorption; separate doses by 4 hours
May cause tachycardia and hypertension
Possible increased metabolism of thyroxine; dosage adjustments may be needed
Decreased conversion of T4 to T3
Possible increased metabolism of thyroxine; dosage adjustments may be needed
May increase levothyroxine requirements
May reduce levothyroxine absorption; separate doses by 4 hours
Levothyroxine can potentiate effects
Thyroid hormones increase the catabolism of vitamin K-dependent clotting factors that may increase the anticoagulation effects
모니터링
- Clinical signs of resolution of hypothyroidism (e.g., improved energy, hair regrowth, weight loss)
- Signs of thyrotoxicosis/hyperthyroidism (tachycardia, panting, weight loss with polyphagia)
- Serum total T4 (TT4) levels (typically measured 4-6 hours post-pill for peak levels)
- Canine TSH (cTSH) if indicated
약동학
반감기
흡수
Wide variability from animal to animal.
대사
Converted in peripheral tissues from T4 to T3.
과다투여
Chronic overdosage will produce signs of hyperthyroidism, including tachycardia, polyphagia, PU/PD, excitability, nervousness, and excessive panting. Some cats (approx. 10%) may exhibit 'apathetic' hyperthyroidism (listlessness, anorexia).
- Management of Chronic OD: Reduce dosage and/or temporarily withhold until signs subside.
- Acute Overdose: Less likely to cause severe thyrotoxicosis than chronic OD. Signs may include vomiting, diarrhea, hyperactivity to lethargy, hypertension, tachycardia, tachypnea, dyspnea, and abnormal pupillary light reflexes. In dogs, signs appear within 1-9 hours.
- Treatment of Acute OD: If ingestion occurred within 2 hours, use standard decontamination protocols (emetics, cathartics, activated charcoal). Provide supportive care (oxygen, artificial ventilation, beta-blockers like propranolol, fluids, dextrose, antipyretics).
제품
제형
- Chewable tablets
- Oral solution
- Injection (lyophilized powder)
- Liquid-filled oral capsules
동물용의약품
- Levothyroxine Sodium Tablets: 0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, 0.8 mg, 1 mg (Soloxine, Levosyn, Thyro-Tabs, Thyrosyn, Thyroxine-L, Thyrozine, Thyrokare)
- Levothyroxine Sodium Tablets Chewable: 0.1 mg to 0.8 mg (Canine Thyroid Chewable Tablets, Nutrived T-4, Heska Thyromed)
- Levothyroxine Oral Solution: 1 mg/mL (Leventa)
- Levothyroxine Sodium Powder: 0.22% (Equine Thyroid Supplement, Thyrozine Powder, Levoxine Powder, Thyro-L, Throxine-L Powder, Equi-Phar Thyrosyn Powder, Thyrokare Powder)
인용의약품
- Levothyroxine Sodium Tablets: 0.025 mg to 0.3 mg (Synthroid, Levothroid, Levoxyl, Unithroid)
- Levothyroxine Sodium Liquid-filled Oral Capsules: 13 mcg to 150 mcg (Tirosint)
- Levothyroxine Powder for Injection lyophilized: 200 mcg & 500 mcg
규제 현황
규제 데이터 없음: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
보관·안정성
Store at room temperature in tight, light-resistant containers. The injectable product should be reconstituted immediately before use; discard unused portions. Do not mix injection with other drugs or IV fluids. Aqueous solutions are reportedly unstable.
보호자 정보
중요: 일관성이 핵심입니다! 음식은 약물 흡수량에 영향을 미칠 수 있으므로 매일 같은 시간에, 이상적으로는 공복에 또는 항상 같은 종류의 음식과 함께 이 약을 투여하십시오.
- 평생 치료: 갑상선 기능 저하증은 일반적으로 평생 관리해야 하는 질환입니다. 수의사와 상의 없이 약물 투여를 중단하지 마십시오.
- 모니터링: 용량이 정확한지 확인하기 위해 반려동물은 정기적인 혈액 검사가 필요합니다. 용량이 너무 적으면 증상이 개선되지 않고, 너무 많으면 부작용이 발생할 수 있습니다.
- 과다 복용 징후 관찰: 반려동물이 물을 너무 많이 마시거나 소변을 많이 보는 경우, 심하게 헐떡이는 경우, 불안해하거나 과잉 행동을 보이는 경우, 또는 식욕이 왕성함에도 불구하고 체중이 감소하는 경우에는 수의사에게 연락하십시오.
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