guanfacine hydrochloride

id: guanfacine
brandNames:
  US:
    - Intuniv
    - Tenex
  CN: []
  EU:
    - Intuniv
  JP:
    - インチュニブ (Intuniv)
  UK:
    - Intuniv
  AU:
    - Intuniv
  CA:
    - Intuniv
genericName:
  en: guanfacine hydrochloride
  zh: 盐酸胍法辛
  ja: グアンファシン塩酸塩
manufacturers:
  - name: Takeda (formerly Shire)
    region: US
    product: Intuniv
  - name: Shionogi
    region: JP
    product: インチュニブ
chemicalStructure:
  smiles: NC(=N)NC(=O)CC1=C(Cl)C=CC=C1Cl
  pubchemCid: 3519
  molecularFormula: C9H9Cl2N3O
  imageUrl: https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/cid/3519/PNG
  wikipediaUrl: https://en.wikipedia.org/wiki/File:Guanfacine.svg
drugClass: non-stimulant
drugClassLabel:
  en: Non-Stimulant
  zh: 非兴奋剂
  ja: 非中枢刺激薬
category: alpha-2 adrenergic agonist
categoryLabel:
  en: Alpha-2 Adrenergic Agonist
  zh: α-2肾上腺素能激动剂
  ja: α2アドレナリン受容体作動薬
controlledSubstance: false
schedule:
  US: Not scheduled
  CN: Not approved
  EU: Not scheduled
  JP: Not scheduled
  UK: Not scheduled
activeIngredient:
  en: guanfacine hydrochloride
  zh: 盐酸胍法辛
  ja: グアンファシン塩酸塩
mechanismOfAction:
  en: Selective alpha-2A adrenergic receptor agonist. Stimulates receptors in the prefrontal cortex, strengthening working memory, reducing distractibility, and improving impulse control. Also has calming effect by reducing sympathetic outflow.
  zh: 选择性α-2A肾上腺素能受体激动剂。刺激前额叶皮层的受体，增强工作记忆，减少分心，改善冲动控制。还通过减少交感神经传出而具有镇静作用。
  ja: 選択的α2Aアドレナリン受容体作動薬。前頭前皮質の受容体を刺激し、ワーキングメモリを強化し、気が散りやすさを軽減し、衝動制御を改善します。また、交感神経出力を減少させることで鎮静効果もあります。
neurotransmittersAffected:
  - norepinephrine
forms:
  - type: tablet
    typeLabel:
      en: Tablet
      zh: 片剂
      ja: 錠剤
    releaseType: extended
    releaseTypeLabel:
      en: Extended Release
      zh: 缓释
      ja: 徐放性
    brandName: Intuniv
    strengths:
      - 1mg
      - 2mg
      - 3mg
      - 4mg
    durationHours: 24
    notes:
      en: Extended-release for ADHD; must swallow whole
      zh: ADHD缓释制剂；需整片吞服
      ja: ADHD用徐放製剤；そのまま飲み込む必要あり
  - type: tablet
    typeLabel:
      en: Tablet
      zh: 片剂
      ja: 錠剤
    releaseType: immediate
    releaseTypeLabel:
      en: Immediate Release
      zh: 速释
      ja: 即放性
    brandName: Tenex
    strengths:
      - 1mg
      - 2mg
    durationHours: 8-12
    notes:
      en: Immediate-release; originally for hypertension; not FDA-approved for ADHD
      zh: 速释制剂；最初用于高血压；未获FDA批准用于ADHD
      ja: 即放性製剤；元々は高血圧用；ADHDにはFDA未承認
onsetMinutes:
peakEffectHours: 5
durationHours: 24
sideEffects:
  common:
    - name:
        en: somnolence/fatigue
        zh: 嗜睡/疲劳
        ja: 傾眠/疲労
      frequency: 30-40%
    - name:
        en: headache
        zh: 头痛
        ja: 頭痛
      frequency: 20-25%
    - name:
        en: dizziness
        zh: 头晕
        ja: めまい
      frequency: 10-15%
    - name:
        en: decreased appetite
        zh: 食欲下降
        ja: 食欲減退
      frequency: 10-15%
    - name:
        en: abdominal pain
        zh: 腹痛
        ja: 腹痛
      frequency: 10%
    - name:
        en: dry mouth
        zh: 口干
        ja: 口渇
      frequency: 10%
    - name:
        en: nausea
        zh: 恶心
        ja: 悪心
      frequency: 5-10%
    - name:
        en: constipation
        zh: 便秘
        ja: 便秘
      frequency: 5%
  uncommon:
    - name:
        en: hypotension
        zh: 低血压
        ja: 低血圧
      frequency: 5-10%
    - name:
        en: bradycardia
        zh: 心动过缓
        ja: 徐脈
      frequency: 5%
    - name:
        en: irritability
        zh: 易怒
        ja: 易刺激性
      frequency: 5%
    - name:
        en: insomnia
        zh: 失眠
        ja: 不眠
      frequency: 5%
  serious:
    - name:
        en: hypotension
        zh: 低血压
        ja: 低血圧
      notes:
        en: Can cause significant drops in blood pressure
        zh: 可导致血压明显下降
        ja: 血圧の著しい低下を引き起こす可能性
    - name:
        en: bradycardia
        zh: 心动过缓
        ja: 徐脈
      notes:
        en: May slow heart rate
        zh: 可能减慢心率
        ja: 心拍数を低下させる可能性
    - name:
        en: syncope
        zh: 晕厥
        ja: 失神
      notes:
        en: Fainting due to blood pressure drop
        zh: 因血压下降导致昏厥
        ja: 血圧低下による失神
    - name:
        en: rebound hypertension
        zh: 反跳性高血压
        ja: リバウンド高血圧
      notes:
        en: If stopped abruptly; must taper
        zh: 突然停药时发生；需逐渐减量
        ja: 急に中止した場合；漸減が必要
    - name:
        en: sedation
        zh: 镇静
        ja: 鎮静
      notes:
        en: Can be severe, especially initially
        zh: 可能很严重，尤其是在初期
        ja: 特に初期は重度になる可能性
contraindications:
  en:
    - Hypersensitivity to guanfacine
    - Severe bradycardia
    - Heart block
  zh:
    - 对胍法辛过敏
    - 严重心动过缓
    - 心脏传导阻滞
  ja:
    - グアンファシンに対する過敏症
    - 重度の徐脈
    - 心ブロック
drugInteractions:
  - drug:
      en: CYP3A4 inhibitors (ketoconazole)
      zh: CYP3A4抑制剂（酮康唑）
      ja: CYP3A4阻害剤（ケトコナゾール）
    severity: moderate
    effect:
      en: Increased guanfacine levels
      zh: 胍法辛血药浓度升高
      ja: グアンファシン濃度の上昇
  - drug:
      en: CYP3A4 inducers (rifampin)
      zh: CYP3A4诱导剂（利福平）
      ja: CYP3A4誘導剤（リファンピン）
    severity: moderate
    effect:
      en: Decreased guanfacine levels
      zh: 胍法辛血药浓度降低
      ja: グアンファシン濃度の低下
  - drug:
      en: Antihypertensives
      zh: 降压药
      ja: 降圧薬
    severity: moderate
    effect:
      en: Additive hypotensive effect
      zh: 降压作用叠加
      ja: 降圧作用の相加
  - drug:
      en: CNS depressants
      zh: 中枢神经抑制剂
      ja: 中枢神経抑制剤
    severity: moderate
    effect:
      en: Enhanced sedation
      zh: 镇静作用增强
      ja: 鎮静作用の増強
  - drug:
      en: Valproic acid
      zh: 丙戊酸
      ja: バルプロ酸
    severity: moderate
    effect:
      en: Increased guanfacine exposure
      zh: 胍法辛暴露量增加
      ja: グアンファシン曝露量の増加
blackBoxWarnings:
  en: []
  zh: []
  ja: []
pregnancyCategory: B
foodInteractions:
  en: Avoid high-fat meals (increases absorption); avoid grapefruit juice
  zh: 避免高脂肪餐（增加吸收）；避免葡萄柚汁
  ja: 高脂肪食を避ける（吸収が増加）；グレープフルーツジュースを避ける
typicalDosing:
  children:
    startingDose: 1mg once daily
    maxDose: 4mg/day (children 6-12) or 7mg/day (adolescents)
    notes:
      en: Increase by 1mg weekly; take at same time daily (morning or evening)
      zh: 每周增加1mg；每天同一时间服用（早上或晚上）
      ja: 毎週1mgずつ増量；毎日同じ時間に服用（朝または夕方）
  adults:
    startingDose: 1mg once daily
    maxDose: 4mg/day (off-label for adults)
    notes:
      en: Not FDA-approved for adult ADHD but commonly used
      zh: 未获FDA批准用于成人ADHD但常用
      ja: 成人ADHDにはFDA未承認だが一般的に使用される
costEstimate:
  US:
    brand: $300-400/month
    generic: $50-100/month
  CN:
    brand: Not available
    generic: Not available
storageRequirements:
  en: Room temperature (25°C), protect from light and moisture
  zh: 室温保存（25°C），避光避湿
  ja: 室温（25°C）で保存、光と湿気を避ける
approvals:
  - region: US
    agency: FDA
    year: 2009
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: Approved for children/adolescents; off-label for adults; can be used alone or with stimulants
      zh: 批准用于儿童/青少年；成人为超说明书使用；可单独使用或与兴奋剂联用
      ja: 小児/青年に承認；成人は適応外使用；単独または刺激薬との併用が可能
  - region: CN
    agency: NMPA
    year:
    approvedAges:
      en: ""
      zh: ""
      ja: ""
    indications:
      en: []
      zh: []
      ja: []
    available: false
    notes:
      en: Not approved in China
      zh: 中国未批准
      ja: 中国では未承認
  - region: EU
    agency: EMA
    year: 2015
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: First ADHD medication approved through EMA centralized procedure
      zh: 首个通过EMA集中审批程序批准的ADHD药物
      ja: EMA集中審査手続きを通じて承認された最初のADHD薬
  - region: JP
    agency: PMDA
    year: 2017
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: No registration requirement (unlike stimulants)
      zh: 无需登记（与兴奋剂不同）
      ja: 登録要件なし（刺激薬とは異なる）
  - region: UK
    agency: MHRA
    year: 2016
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: ""
      zh: ""
      ja: ""
  - region: AU
    agency: TGA
    year: 2013
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: ""
      zh: ""
      ja: ""
  - region: CA
    agency: Health Canada
    year: 2013
    approvedAges:
      en: 6-17 years
      zh: 6-17岁
      ja: 6〜17歳
    indications:
      en:
        - ADHD
      zh:
        - 注意缺陷多动障碍
      ja:
        - ADHD
    available: true
    notes:
      en: ""
      zh: ""
      ja: ""
specialConsiderations:
  cardiacRisk:
    en: Can lower blood pressure and heart rate; use caution with cardiac conditions
    zh: 可降低血压和心率；有心脏病者需谨慎
    ja: 血圧と心拍数を低下させる可能性；心臓疾患には注意
  abuseRisk:
    en: No abuse potential; not a controlled substance
    zh: 无滥用风险；非管制药物
    ja: 乱用の可能性なし；規制物質ではない
  withdrawalNotes:
    en: MUST TAPER - stopping abruptly can cause rebound hypertension
    zh: 必须逐渐减量 - 突然停药可导致反跳性高血压
    ja: 必ず漸減すること - 急な中止はリバウンド高血圧を引き起こす可能性
  monitoringRequired:
    en: Blood pressure, heart rate; especially when starting or changing dose
    zh: 血压、心率；尤其是开始用药或调整剂量时
    ja: 血圧、心拍数；特に開始時または用量変更時
travelRules:
  generalAdvice:
    en: Guanfacine is NOT a controlled substance, making travel straightforward. However, it's not available in all countries (notably China). Carry prescription documentation.
    zh: 胍法辛不是管制药物，旅行较为简单。但并非所有国家都有供应（特别是中国）。请携带处方文件。
    ja: グアンファシンは規制物質ではないため、旅行は簡単です。ただし、すべての国で入手できるわけではありません（特に中国）。処方書類を携帯してください。
  requiredDocumentation:
    - type: prescription
      typeLabel:
        en: Valid prescription
        zh: 有效处方
        ja: 有効な処方箋
      notes:
        en: Recommended for longer trips
        zh: 长途旅行建议携带
        ja: 長期旅行の場合は推奨
  maxPersonalSupply:
    default: 90 days
  crossBorderRules:
    - fromRegion: US
      toRegion: JP
      status: allowed
      statusLabel:
        en: Allowed
        zh: 允许
        ja: 許可
      requirements:
        en:
          - Carry prescription copy
          - Keep in original packaging
        zh:
          - 携带处方副本
          - 保持原包装
        ja:
          - 処方箋のコピーを携帯
          - 元のパッケージを維持
      maxSupply: 90 days
      notes:
        en: Guanfacine is approved in Japan and is not a controlled substance. No special permit required.
        zh: 胍法辛在日本已获批且不是管制药物。无需特别许可。
        ja: グアンファシンは日本で承認されており、規制物質ではありません。特別な許可は不要です。
    - fromRegion: US
      toRegion: CN
      status: restricted
      statusLabel:
        en: Restricted - Not Available
        zh: 受限 - 不可用
        ja: 制限あり - 入手不可
      requirements:
        en:
          - Carry prescription and doctor's letter
          - Keep in original packaging
        zh:
          - 携带处方和医生证明信
          - 保持原包装
        ja:
          - 処方箋と医師の手紙を携帯
          - 元のパッケージを維持
      maxSupply: 90 days
      notes:
        en: Guanfacine is NOT approved in China. You may bring personal supply but cannot obtain refills locally.
        zh: 胍法辛在中国未获批准。可以携带个人使用量，但无法在当地补充。
        ja: グアンファシンは中国では未承認です。個人使用分は持ち込めますが、現地での補充はできません。
    - fromRegion: US
      toRegion: EU
      status: allowed
      statusLabel:
        en: Allowed
        zh: 允许
        ja: 許可
      requirements:
        en:
          - Carry prescription copy
        zh:
          - 携带处方副本
        ja:
          - 処方箋のコピーを携帯
      maxSupply: 90 days
      notes:
        en: Guanfacine is approved in EU. No special import requirements.
        zh: 胍法辛在欧盟已获批。无特殊进口要求。
        ja: グアンファシンはEUで承認されています。特別な輸入要件はありません。
rxnormData:
  ingredientRxcui: "40114"
  ingredientName: guanfacine
  rxcuiMappings:
    - rxcui: "40114"
      name: guanfacine
      tty: IN
      description: Base ingredient
    - rxcui: "862007"
      name: Intuniv
      tty: BN
      description: Brand name
    - rxcui: "203142"
      name: guanfacine hydrochloride
      tty: PIN
      description: Precise ingredient (includes salt form)
    - rxcui: "862004"
      name: guafacine hydrochloride
      tty: PIN
      description: Precise ingredient (includes salt form)
    - rxcui: "862010"
      name: 24 HR guanfacine 1 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      description: Branded drug (brand + strength + form)
    - rxcui: "862015"
      name: 24 HR guanfacine 2 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      description: Branded drug (brand + strength + form)
    - rxcui: "862021"
      name: 24 HR guanfacine 3 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      description: Branded drug (brand + strength + form)
    - rxcui: "862027"
      name: 24 HR guanfacine 4 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      description: Branded drug (brand + strength + form)
    - rxcui: "862009"
      name: guanfacine Extended Release Oral Tablet [Intuniv]
      tty: SBDF
      description: Branded ingredient + dose form
    - rxcui: "197745"
      name: guanfacine 1 MG Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "197746"
      name: guanfacine 2 MG Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "862006"
      name: 24 HR guanfacine 1 MG Extended Release Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "862013"
      name: 24 HR guanfacine 2 MG Extended Release Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "862019"
      name: 24 HR guanfacine 3 MG Extended Release Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "862025"
      name: 24 HR guanfacine 4 MG Extended Release Oral Tablet
      tty: SCD
      description: Clinical drug (ingredient + strength + form)
    - rxcui: "372368"
      name: guanfacine Oral Tablet
      tty: SCDF
      description: Ingredient + dose form
    - rxcui: "862005"
      name: guanfacine Extended Release Oral Tablet
      tty: SCDF
      description: Ingredient + dose form
  brandMappings:
    - brandName: Intuniv
      rxcui: "862007"
      region: US
    - brandName: Tenex
      rxcui: ""
      region: US
  synonyms:
    - name: guanfacine hydrochloride
      type: chemical
      source: RxNorm
    - name: guafacine hydrochloride
      type: chemical
      source: RxNorm
    - name: Intuniv
      type: brand
      source: RxNorm
    - name: guanfacine
      type: generic
      source: RxNorm
  relatedDrugs:
    - rxcui: "197745"
      name: guanfacine 1 MG Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "197746"
      name: guanfacine 2 MG Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "862006"
      name: 24 HR guanfacine 1 MG Extended Release Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "862013"
      name: 24 HR guanfacine 2 MG Extended Release Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "862019"
      name: 24 HR guanfacine 3 MG Extended Release Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "862025"
      name: 24 HR guanfacine 4 MG Extended Release Oral Tablet
      tty: SCD
      relationship: clinical_drug
    - rxcui: "862010"
      name: 24 HR guanfacine 1 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      relationship: branded_drug
    - rxcui: "862015"
      name: 24 HR guanfacine 2 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      relationship: branded_drug
    - rxcui: "862021"
      name: 24 HR guanfacine 3 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      relationship: branded_drug
    - rxcui: "862027"
      name: 24 HR guanfacine 4 MG Extended Release Oral Tablet [Intuniv]
      tty: SBD
      relationship: branded_drug
    - rxcui: "372368"
      name: guanfacine Oral Tablet
      tty: SCDF
      relationship: drug_form
    - rxcui: "862005"
      name: guanfacine Extended Release Oral Tablet
      tty: SCDF
      relationship: drug_form
  lastUpdated: 2025-12-04
instructions:
  indicationsAndUsage:
    en: |
      Guanfacine extended-release (Intuniv) is a selective alpha2A-adrenergic receptor agonist indicated for the treatment of:
      - Attention Deficit Hyperactivity Disorder (ADHD) in patients 6-17 years of age as monotherapy or adjunctive therapy to stimulants

      Note: Immediate-release guanfacine (Tenex) is FDA-approved only for hypertension; ADHD use is off-label. Intuniv is specifically formulated for once-daily ADHD treatment.
  dosageAndAdministration:
    en: |
      ADHD (INTUNIV):
      - Starting dose: 1 mg once daily
      - Titration: Increase by increments of no more than 1 mg/week
      - Target dose: 1-4 mg once daily
      - Maximum dose: 4 mg/day (children 6-12); 7 mg/day (adolescents 13-17)

      Weight-Based Dosing:
      - 25-33 kg: 2 mg/day recommended
      - 34-41 kg: 3 mg/day recommended
      - 42-49 kg: 4 mg/day recommended
      - 50-58 kg: 5 mg/day recommended
      - 59-91 kg: 6 mg/day recommended
      - ≥91 kg: 7 mg/day recommended

      ADJUNCTIVE THERAPY WITH STIMULANTS:
      - Same dosing as monotherapy
      - If discontinuing stimulant, maintain guanfacine dose

      General Instructions:
      - Take once daily in the morning or evening at same time each day
      - Do NOT crush, chew, or break tablets (compromises extended-release)
      - May be taken with or without food
      - Avoid high-fat meals (increases absorption)

      DISCONTINUATION:
      - Taper dose gradually over 3-7 days to avoid rebound hypertension
      - Do NOT stop abruptly
  dosageForms:
    en: |
      Extended-Release Tablets (Intuniv): 1 mg, 2 mg, 3 mg, 4 mg
      Immediate-Release Tablets (Tenex): 1 mg, 2 mg (not FDA-approved for ADHD)
  contraindications:
    en: |
      Guanfacine is contraindicated in patients with:
      - Known hypersensitivity to guanfacine or any ingredients in the formulation

      CAUTIONS:
      - Hypotension
      - Bradycardia
      - Syncope
      - Sedation
  warningsAndPrecautions:
    en: |
      HYPOTENSION, BRADYCARDIA, AND SYNCOPE:
      - Can cause dose-dependent decreases in blood pressure and heart rate
      - Syncope has been reported
      - Use caution in patients at risk: dehydration, hypotension, heart block, bradycardia, cardiovascular disease, or taking antihypertensives
      - Monitor blood pressure and heart rate before and during treatment

      SEDATION AND SOMNOLENCE:
      - Common adverse reaction, especially early in treatment
      - More pronounced with higher doses
      - Caution patients about driving or operating machinery until effects are known
      - Sedation may decrease with continued treatment

      CARDIAC CONDUCTION ABNORMALITIES:
      - May increase risk of QT prolongation with other QT-prolonging drugs

      ABRUPT DISCONTINUATION:
      - Rebound hypertension may occur
      - Taper dose gradually (decrease by no more than 1 mg every 3-7 days)
  adverseReactions:
    en: |
      Most Common Adverse Reactions (≥5%):
      Monotherapy:
      - Somnolence (38%)
      - Headache (24%)
      - Fatigue (14%)
      - Upper abdominal pain (10%)
      - Nausea (6%)
      - Lethargy (6%)
      - Dizziness (6%)
      - Irritability (6%)
      - Hypotension/decreased blood pressure (6%)
      - Decreased appetite (5%)

      Adjunctive Therapy with Stimulants:
      - Headache
      - Insomnia
      - Somnolence
      - Fatigue
      - Dizziness
      - Abdominal pain
  drugInteractions:
    en: |
      USE WITH CAUTION:
      - CYP3A4 Inhibitors (ketoconazole, ritonavir): Increase guanfacine plasma concentrations; consider dose reduction
      - CYP3A4 Inducers (rifampin): Decrease guanfacine plasma concentrations; consider dose increase
      - Antihypertensives: Additive effects on blood pressure and heart rate
      - CNS Depressants: Additive sedative effects
      - Alcohol: Additive sedation and CNS depression
      - Valproic acid: May increase valproic acid levels

      NO SIGNIFICANT INTERACTIONS:
      - No clinically significant interaction with methylphenidate or lisdexamfetamine when used as adjunctive therapy
  useInSpecificPopulations:
    en: |
      PREGNANCY:
      - Category B (animal studies showed no risk; no adequate human studies)
      - Use only if clearly needed

      LACTATION:
      - Unknown if excreted in human milk
      - Consider benefits vs. risks before use during breastfeeding

      PEDIATRIC USE:
      - Safety and efficacy established for patients 6-17 years
      - Not studied in children under 6 years

      GERIATRIC USE:
      - Clinical studies did not include sufficient patients 65 and older

      RENAL IMPAIRMENT:
      - Consider dose reduction in patients with significant renal impairment

      HEPATIC IMPAIRMENT:
      - Consider dose reduction in patients with hepatic impairment
  overdosage:
    en: |
      SIGNS AND SYMPTOMS:
      - Drowsiness, lethargy
      - Bradycardia
      - Hypotension
      - Initial hypertensive response possible

      TREATMENT:
      - Provide supportive care
      - Monitor vital signs
      - Gastric lavage if recent ingestion
      - Guanfacine is not dialyzable in clinically significant amounts
  clinicalPharmacology:
    en: |
      MECHANISM OF ACTION:
      Guanfacine is a selective alpha2A-adrenergic receptor agonist. It is thought to work in ADHD by:
      - Strengthening prefrontal cortex function
      - Enhancing working memory
      - Reducing distractibility
      - Improving impulse control
      - Reducing sympathetic nervous system activity

      Unlike stimulants, guanfacine does not increase dopamine in the nucleus accumbens, which may explain its lack of abuse potential.

      PHARMACOKINETICS:
      - Absorption: Peak plasma concentration at 5 hours (extended-release)
      - Distribution: 70% protein bound; moderate volume of distribution
      - Metabolism: Hepatic via CYP3A4
      - Half-life: 17 hours (extended-release); allows once-daily dosing
      - Excretion: 80% renal (50% unchanged)
  howSupplied:
    en: |
      STORAGE AND HANDLING:
      - Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F)
      - Protect from light and moisture

      Not a Controlled Substance - No DEA Schedule
  patientCounselingInfo:
    en: |
      IMPORTANT PATIENT INFORMATION:

      1. DOSING: Take at the same time each day (morning or evening). Swallow tablets whole - do NOT crush, chew, or break.

      2. DO NOT STOP SUDDENLY: This medication must be tapered gradually to avoid rebound high blood pressure. Talk to your doctor before stopping.

      3. DROWSINESS: This medication commonly causes drowsiness, especially when starting. Avoid driving or operating machinery until you know how it affects you.

      4. LOW BLOOD PRESSURE: You may feel dizzy when standing up quickly. Rise slowly from sitting or lying positions.

      5. AVOID ALCOHOL: Alcohol increases drowsiness and can worsen side effects.

      6. FOOD: May be taken with or without food. Avoid high-fat meals as they increase absorption.

      7. HEART MONITORING: Blood pressure and heart rate will be checked regularly during treatment.

      8. MISSED DOSE: If you miss a dose, skip it if more than 2 consecutive doses are missed; consult your doctor about restarting.

      9. NOT A STIMULANT: This is a non-stimulant medication. It may take 2-3 weeks to see full effect.

      10. ADJUNCTIVE USE: This medication can be used alone or with stimulant medications.
lastUpdated: 2025-12-04
sources:
  - https://www.goodrx.com/conditions/adhd/non-stimulant-adhd-meds
  - https://www.ema.europa.eu/en/news/ema-recommends-approval-treatment-attention-deficit-hyperactivity-disorder
  - https://h-navi.jp/column/article/35028853
notes:
  en: Good option for hyperactivity/impulsivity symptoms or when stimulants cause anxiety. Particularly helpful for emotional dysregulation. Can be combined with stimulants. Must taper when discontinuing. Not approved for adult ADHD but commonly used off-label.
  zh: 适用于多动/冲动症状或兴奋剂引起焦虑时。对情绪失调特别有帮助。可与兴奋剂联用。停药时必须逐渐减量。未批准用于成人ADHD但常用于超说明书使用。
  ja: 多動性/衝動性の症状、または刺激薬が不安を引き起こす場合に良い選択肢。感情調節障害に特に有用。刺激薬と併用可能。中止時は漸減が必要。成人ADHDには未承認だが適応外使用が一般的。