Core32: Special groups - drug interactions: childhood

👶 High-yield / 要点：Children are not small adults. Drug choice must consider developmental toxicity, age-dependent PK/PD, limited safety data, and longer lifetime risk.

Why children differ / 小児が成人と異なる理由

• Pharmacokinetics differs by age.
  • Total body water: adult ~60%, newborn ~80%.
• Developing organs/tissues can be harmed by certain drugs.
• Some drugs safe in adults can cause severe adverse effects in children.
• Longer life expectancy makes late adverse effects more important.
• Efficacy may differ due to PK/PD differences.
• Many medicines have limited pediatric safety data.

Important examples / 重要例

• Doxycycline/tetracyclines：slows bone and dental development.
• Valproate：severe liver damage in babies under 2 years; pancreatitis.
• Aspirin：Reye syndrome during viral infection.
• Cyclophosphamide：later malignancy or infertility risk.
• Some antibiotics may need higher doses because of augmented clearance.

Drugs to avoid in childhood / 小児で避ける薬

Drug / group	Main risk
Estrogens, androgens	Stop longitudinal growth
Aspirin	Reye syndrome: liver damage + encephalopathy in viral infection
Valproate	Severe liver damage under 2 years; pancreatitis
Mebendazole	Lack of data under 2 years
Tetracyclines, doxycycline	Bone and dental development problems
Chloramphenicol	Gray baby syndrome in newborns
Fluoroquinolones	Skeletal adverse effects
Sulfamethoxazole	Kernicterus risk in newborns
Codeine	Respiratory depression
Olanzapine	Metabolic syndrome

Remember / 覚え方

• Child ≠ small adult
• Developing bone/teeth/liver/CNS matter
• Aspirin → Reye
• Tetracyclines → teeth/bone
• Codeine → respiratory depression