コデイン
Codeine
Codeine phosphate, Codeine sulfate
別名: Tylenol with Codeine · Empirin with Codeine · Pardale-V · Co-codamol (human combination) · Codeine phosphate hemihydrate · Codeini phosphas hemihydricus · Codeinii phosphas · Codeinum · Methylmorphine · Codeine sulfate
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
監査済み v13 用量エビデンス
構造化された用量計算エビデンスAntitussive (extra-label)
認証済み獣医師の確認が必要
- q6-12h
NA
必ず考慮する臨床コンテキスト (2)
- ■ This medicine may be given with food or on an empty stomach.
- Store codeine sulfate tablets in light-resistant, well-closed containers at room temperature 15°C to 30°C (59°F-86°F).
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。
概要
コデインはフェナントレン誘導体のオピオイド作動薬であり、獣医学では主に鎮咳薬（咳止め）および軽度の鎮痛薬として使用されます。止瀉薬として使用されることもあります。
- 鎮痛：軽度から中等度の疼痛に使用され、NSAIDsが無効または禁忌の場合によく用いられます。
- 鎮咳：非生産性の咳（気管虚脱、慢性気管支炎など）の抑制に非常に有効です。
- 止瀉：消化管の運動を低下させます。
臨床上のポイント：人医療では広く使用されていますが、犬での使用には議論があります。犬は経口コデインの吸収が非常に悪く、活性代謝物（モルヒネ）に変換するための強力な酵素経路を欠いています。そのため、犬における鎮痛効果は非常にばらつきがあり、一般的にブプレノルフィンやメタドンなどの他のオピオイドに劣ると考えられています。
作用機序
Codeine acts as a weak agonist at mu (μ) opioid receptors.
- Analgesia: Binds to μ-receptors in the central nervous system → inhibits the release of excitatory neurotransmitters (such as Substance P) in ascending pain pathways → alters the perception of and response to pain.
- Antitussive: Causes direct depression of the medullary cough center in the brainstem.
- Antidiarrheal: Binds to enteric μ-receptors → decreases gastrointestinal motility and increases sphincter tone.
- Metabolism Note: In humans, codeine is a prodrug metabolized by the enzyme CYP2D6 → morphine. Dogs lack significant CYP2D6-equivalent activity, relying mostly on codeine-6-glucuronide for any analgesic effect, which explains its limited efficacy in this species.
安全性・警告
禁忌
- Hypersensitivity to narcotic analgesics
- Patients receiving monoamine oxidase inhibitors (MAOIs) like amitraz or selegiline
- Diarrhea caused by toxic ingestion (until toxin is eliminated)
- Repeated use in severe inflammatory bowel disease
- Scorpion stings (Centruroides sculpturatus and C. gertschi) as it may potentiate venom
- Combination products containing acetaminophen are STRICTLY CONTRAINDICATED in cats
- Hypersensitivity to opioids
- Severe respiratory depression or asthma
- Cats (especially if using combination products containing paracetamol)
有害事象
- Sedation (most common)
- Constipation
- Anorexia
- Vomiting
- Ileus
- Biliary and pancreatic duct spasms
- Respiratory depression (at high doses)
- Cats: CNS stimulation, hyperexcitability, tremors, seizures
- Nausea
注意事項
Use with caution in patients with hypothyroidism, severe renal insufficiency, Addison's disease, and in geriatric or severely debilitated patients.
Use with caution in patients with head injuries or increased intracranial pressure, and in those with acute abdominal conditions (e.g., colic) as it may obscure the diagnosis.
Use with extreme caution in patients suffering from respiratory disease or acute respiratory dysfunction (e.g., pulmonary edema secondary to smoke inhalation).
Warning: Opiates can increase plasma amylase and lipase values up to 24 hours following administration due to increased biliary tract pressure.
医薬品相互作用
May increase the chances of constipation developing
May potentiate CNS depressant effects
May cause increased CNS or respiratory depression
May inhibit the transformation of codeine to morphine in the liver, decreasing its efficacy
Additive CNS and respiratory depression
Increased risk of serotonin syndrome
Additive CNS and respiratory depression
May cause severe, unpredictable reactions (serotonin syndrome or severe respiratory depression)
監視
- Efficacy (pain relief, reduction in coughing, or resolution of diarrhea)
- Adverse effects (sedation, respiratory rate, GI signs)
- Respiratory rate and depth
- Level of sedation
- Pain score or coughing frequency
- Bowel movements (monitor for constipation)
薬物動態
半減期
吸収
Very limited evidence of oral absorption in dogs. In humans, codeine salts are rapidly absorbed orally, with oral administration being about 2/3 as effective as parenteral. Onset of action is usually within 30 minutes.
分布
Crosses the placenta and enters maternal milk.
代謝
Metabolized in the liver.
消失
Excreted into the urine.
過剰投与
Opiate overdosage may produce profound respiratory and/or CNS depression. Other effects can include cardiovascular collapse, hypothermia, and skeletal muscle hypotonia.
- Decontamination: Oral ingestions should be removed using standard gut removal protocols. Inducing vomiting should be attempted with caution due to rapid changes in CNS status.
- Antidote: Naloxone is the agent of choice for treating respiratory depression. In massive overdoses, naloxone doses may need to be repeated, as its effects may diminish before subtoxic levels of codeine are attained.
- Supportive Care: Mechanical respiratory support should be considered in cases of severe respiratory depression. Contact an animal poison control center for further guidance.
製品
製剤
- Tablets
- Oral solution/elixir
- Parenteral injection
- Combination products (with acetaminophen, aspirin, or guaifenesin)
- 3 mg/5 ml paediatric linctus
- 3 mg/ml linctus
- 5 mg/ml syrup
- 15 mg tablet
- 30 mg tablet
- 60 mg tablet
動物用医薬品
- Pardale-V tablets (Combination: Paracetamol 400 mg + Codeine phosphate 9 mg)
ヒト用医薬品
- Codeine Phosphate Solution: 15 mg/5 mL
- Codeine Sulfate Tablets: 15 mg, 30 mg & 60 mg
- Codeine Phosphate Parenteral Injection: 15 mg/mL & 30 mg/mL
- Codeine Phosphate Antitussives with expectorants (e.g., with guaifenesin)
- Codeine Phosphate with Acetaminophen tablets (Tylenol® with Codeine #1, #2, #3, #4)
- Codeine Phosphate with Aspirin tablets (Empirin® with Codeine #2, #3, #4)
- Codeine linctus (3 mg/ml, 3 mg/5 ml)
- Codeine syrup (5 mg/ml)
- Codeine tablets (15 mg, 30 mg, 60 mg)
規制ステータス
Availability of veterinary specific products varies by member state.
Classified as POM-V or POM depending on the specific product (e.g., Pardale-V is POM-V).
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Codeine phosphate and sulfate tablets should be stored in light-resistant, well-closed containers at room temperature. Codeine phosphate injection should be stored at room temperature (avoid freezing) and protected from light. Do not use the injection if discolored or if it contains a precipitate.
飼主向け情報
- 子供やペットの手の届かないところに保管してください：これは規制薬物です。
- 猫に対する毒性：アセトアミノフェンを含む製品（例：Tylenol® with Codeine）は絶対に猫に与えないでください。急速に死に至る危険があります。
- 副作用：極度の眠気、便秘、食欲不振、嘔吐に注意してください。猫は時折、異常に活動的になったり、神経質になったり、震えたりすることがあります。
- 獣医師への連絡のタイミング：行動や活動レベルの重大な変化、または重度の胃腸症状が見られた場合は、直ちに獣医師に報告してください。
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