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ナイアシンアミド

Niacinamide

Nicotinamide

免疫調節薬 / 栄養補助食品PO犬

別名: Vitamin PP · Niacinamide · Nicotinamide · Nicotinamidum · Nicotinic acid amide · Nicotylamide · Vitamin B3 amide

VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス

For dogs weighing 10 kg or more: 500 mg of niacinamide and 500 mg of tetracycline PO q8h. For dogs weighing from 5-10 kg: 250 mg of each drug PO q8h. For dogs weighing less than 5 kg: 100 mg of each drug PO q8h.PO· q8h· Improvement usually noted within 6 weeks
500 mg — 個体ごとの固定用量（体重換算なし）

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

動物種別用量

🌎 NA — North America🌍 EU — Europe

犬

適応用量経路頻度期間地域
Discoid lupus erythematosusFor dogs weighing 10 kg or more: 500 mg of niacinamide and 500 mg of tetracycline PO q8h. For dogs weighing from 5-10 kg: 250 mg of each drug PO q8h. For dogs weighing less than 5 kg: 100 mg of each drug PO q8h.POq8hImprovement usually noted within 6 weeks🌎 NA
Discoid lupus erythematosus or pemphigusDogs weighing more than 10 kg: 500 mg of niacinamide and 500 mg of tetracycline PO q8h. For dogs weighing less than 10 kg: 250 mg of each PO q8h.POq8h—🌎 NA
Various immune-mediated diseases (DLE, pemphigus, vasculitis, dermatomyositis, etc.)For dogs less than 10 kg: 250 mg each of niacinamide and tetracycline PO three times daily. For dogs larger than 10 kg: 500 mg each of niacinamide and tetracycline PO three times daily.POTID—🌎 NA
Pemphigus foliaceousDoses as above (with prednisone and azathioprine). Once remission has occurred the dose may be gradually tapered to once daily administration.POTID initially, taper to q24hImprovement within 1-2 months🌎 NA
Adjunctive therapy for pemphigus or discoid lupus erythematosus100 mg of each for dogs <5kg; 250 mg of each for dogs 5-10 kg; 500 mg of each for dogs >10 kg PO three times daily until resolve (90-120 days), then decrease by one dose per day per month (three times daily to two times daily to once daily and eventually to every other day for 30-60 days.)POTID initially, then tapered90-120 days initially, then 30-60 days taper🌎 NA
Immunomodulation (e.g., lupoid onychodystrophy, discoid lupus erythematosus, pemphigus foliaceus)250 mg/dog (dogs up to 25 kg), 500 mg/dog (dogs >25 kg)POq8hTaper to effect🌍 EU
  • Discoid lupus erythematosus: Given in combination with tetracycline.
  • Discoid lupus erythematosus or pemphigus: May use in combination with corticosteroids and Vitamin E. If adverse effects become a problem, reduce dose of niacinamide first.
  • Various immune-mediated diseases (DLE, pemphigus, vasculitis, dermatomyositis, etc.): May substitute doxycycline for tetracycline at 5 mg/kg PO once a day.
  • Pemphigus foliaceous: Used as adjunctive therapy.
  • Adjunctive therapy for pemphigus or discoid lupus erythematosus: Given with tetracycline.
  • Immunomodulation (e.g., lupoid onychodystrophy, discoid lupus erythematosus, pemphigus foliaceus): Often used in combination with oxytetracycline, tetracycline, or doxycycline.

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

診察中ですか？VetSheet の AI が薬剤・用量・投与期間を構造化された診察記録に直接記入します。VetSheet の仕組みを見る

概要

ナイアシンアミド（ニコチンアミドとも呼ばれる）は、水溶性ビタミンB3のアミド型です。組織呼吸や脂質代謝に不可欠な栄養素として機能しますが、獣医薬理学における主な用途は​免疫調節薬​としてです。

犬の医療では、免疫介在性皮膚疾患を管理するために、​テトラサイクリン​（またはドキシサイクリン）との相乗的な組み合わせで処方されることが最も一般的です。特に​円板状エリテマトーデス（DLE）​や​紅斑性天疱瘡​に有効であり、罹患犬の25％〜65％で有効性を示します。

​臨床のポイント：​ ナイアシンアミドとナイアシン（ニコチン酸）を区別することが重要です。ナイアシンとは異なり、ナイアシンアミドは皮膚の血管拡張（「ナイアシンフラッシュ」）を引き起こさず、血中脂質レベルや心血管系に影響を与えないため、犬の長期的な免疫調節において安全で適切な選択肢となります。

作用機序

At pharmacologic doses, niacinamide exerts anti-inflammatory and immunomodulatory effects through several pathways:

  • ​Mast Cell Stabilization:​ Blocks IgE-induced histamine release and prevents the degranulation of mast cells.
  • ​Enzyme Inhibition:​ Inhibits ​phosphodiesterase (PDE)​ enzymes → increases intracellular cAMP → decreases the release of inflammatory proteases.
  • ​Synergy with Tetracyclines:​ When used concurrently with tetracycline or doxycycline, the combination suppresses leukocyte chemotaxis that occurs secondary to complement activation by antibody-antigen complexes.
  • ​Nutritional Role:​ Acts as a precursor to NAD and NADP, essential coenzymes for tissue respiration, glycogenolysis, and lipid metabolism.

安全性・警告

禁忌

  • Liver disease
  • Active peptic ulcers
  • Hypersensitivity to niacinamide
  • Do not use nicotinic acid (niacin) as a substitute due to severe vasodilation (flushing) effects.

有害事象

  • Lethargy
  • Elevated liver enzymes (occasional)
  • Increased seizure frequency (anecdotal)
  • Mild gastrointestinal irritation (anorexia, vomiting, diarrhea)

注意事項

Use with caution in dogs with a history of seizures. While niacinamide alone is generally considered safe in pregnant and lactating animals, its common concurrent use with tetracycline may not be safe during pregnancy/nursing.

医薬品相互作用

Insulin

May require dosage adjustments after initiating niacinamide therapy due to potential alterations in glycemic control.

Oral Antidiabetic Agents

May require dosage adjustments after initiating niacinamide therapy.

監視

  • Clinical efficacy (resolution of dermatologic lesions)
  • Adverse effects (GI upset, lethargy)
  • Liver enzymes (baseline and occasional monitoring suggested)
  • Clinical resolution of dermatological lesions
  • Gastrointestinal signs (vomiting, diarrhea, anorexia)
  • Liver enzymes (if used long-term or at high doses)

薬物動態

半減期

猫Unknown犬Unknown

吸収

Absorbed well after oral administration.

分布

Widely distributed to body tissues.

代謝

Metabolized in the liver to several metabolites.

消失

Excreted into the urine. At physiologic doses, only a small amount is excreted unchanged, but as dosages increase, larger quantities are excreted unchanged.

過剰投与

Acute toxicity is rare. Overdoses are unlikely to cause significant problems other than acute gastrointestinal distress (vomiting, diarrhea).

製品

製剤

  • Tablets
  • 250 mg oral tablet

ヒト用医薬品

  • Niacinamide (Nicotinamide) Tablets: 100 mg & 500 mg (OTC)
  • Nicotinamide 50 mg tablets
  • Nicotinamide 250 mg tablets

規制ステータス

European Union✓ 承認済みEMA
🐕 Dogs

Available as general sale.

United Kingdom✓ 承認済みVMD
🐕 Dogs

Available as general sale.

規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

保管・安定性

Store tablets in tight containers at room temperature unless otherwise labeled. Incompatible with alkalis or strong acids.

飼主向け情報

  • ​指示通りに投与してください：​ この薬は通常、免疫介在性の皮膚疾患を治療するために、抗生物質（テトラサイクリンやドキシサイクリンなど）と一緒に投与されます。
  • ​根気よく続けてください：​ 犬の皮膚に目立った改善が見られるまで、通常​6〜8週間​（場合によっては最大2ヶ月）かかります。
  • ​副作用に注意してください：​ 犬が嘔吐、食欲不振、または異常な疲労感を示した場合は、獣医師に連絡してください。
  • ​代替品を使用しないでください：​ 必ず​ナイアシンアミド​（またはニコチンアミド）を使用し、​ナイアシン​（ニコチン酸）は使用しないでください。ナイアシンは不快な紅潮やその他の副作用を引き起こす可能性があります。
  • 皮膚の状態が良くなったからといって、急に薬をやめないでください。獣医師が徐々に薬を減らすスケジュールを指示します。

VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。