薬物相互作用

簡潔に

Kava can interact with medicines and other central nervous system depressants. Laboratory findings show several possible CYP inhibitions, but small human studies do not confirm one uniform pattern across all enzymes. Alcohol and sedatives in particular should not be self-combined; regular medication warrants individual review.

重要な警告

Kava can interact with medicines and other central nervous system depressants. Laboratory findings show several possible CYP inhibitions, but small human studies do not confirm one uniform pattern across all enzymes. Alcohol and sedatives in particular should not be self-combined; regular medication warrants individual review.

●アルコール – Additive drowsiness and impaired coordination are possible; concurrent use is not recommended
●ベンゾジアゼピン – Possible additive CNS depression; combine only after professional review
●抗精神病薬 – Sedation and pharmacokinetic interactions are possible; direct clinical data are limited
●抗凝固薬 – Controlled interaction data are lacking; the narrow therapeutic window requires medical review

シトクロムP450システム

シトクロムP450システム（CYP450）は、肝臓に存在する酵素のファミリーで、ほとんどの薬物の代謝を担当しています。物質がこれらの酵素を抑制すると、他の物質の代謝が遅くなり、その効果や副作用が強まる可能性があります。

なぜ重要なのか？

Many medicines are metabolised by CYP enzymes. An in-vitro finding does not automatically mean clinically relevant inhibition in humans. Preparation, dose, duration and the medicine's therapeutic window determine practical relevance.

どの酵素が抑制されるのか？

Mathews et al. (2002) tested kava extract and individual kavalactones in human liver microsomes and found inhibition of several CYP enzymes. These are in-vitro findings, not clinical inhibition ratings in humans:

酵素	抑制強度	重要な基質（例）
CYP1A2	In-vitro finding	カフェイン、テオフィリン、クロザピン、オランザピン
CYP2C9	In-vitro finding	ワルファリン、フェニトイン、NSAIDs（イブプロフェン）
CYP2C19	In-vitro finding	オメプラゾール、ジアゼパム、クロピドグレル
CYP2D6	In-vitro finding	コデイン、トラマドール、多くの抗うつ薬
CYP3A4	In-vitro finding	ベンゾジアゼピン、スタチン、多くの抗生物質

臨床的意義

Russmann et al. (2005) reported reduced CYP1A2 activity in chronic users of traditional aqueous kava. Gurley et al. (2005; 12 healthy volunteers, 28 days, 138 mg kavalactones/day), by contrast, found reduced CYP2E1 but no significant change in CYP1A2, CYP2D6 or CYP3A4/5. The human findings are small and preparation- and consumption-dependent, so they cannot predict every medicine interaction.

No established protective benefit

Possible protection against environmental carcinogens has been discussed as a hypothesis but not demonstrated as a clinical benefit. It is neither a reason to consume kava nor a safety guarantee.

高リスクの組み合わせ

The following combinations should be avoided or medically reviewed in advance. Reasons differ: some involve additive CNS effects or case reports, while others have only mechanistic signals and no controlled combination trials.

⚠ アルコール

Risiko: AVOID

Concurrent use of kava and alcohol is not recommended:

1.Additive CNS effects: Drowsiness, slower reactions and impaired coordination may increase.
2.Liver risk not quantified: A combined liver risk has not been quantified reliably; the combination is avoided because of this uncertainty.
3.Unpredictable intensity: Product, amount, drinking pattern and individual sensitivity make effects difficult to predict.

Do not use kava and alcohol together. The main practical reason is possible additive impairment of attention, reaction and coordination; the size of any additional liver risk is not reliably established.

⚠ ベンゾジアゼピンと睡眠薬

Risiko: PROFESSIONAL REVIEW

Do not combine benzodiazepines or Z-drugs with kava without medical review:

•Additive sedation: Drowsiness and psychomotor impairment may increase.
•CNS depression: Clinically relevant potentiation is possible; controlled combination trials are lacking.
•Interpret CYP findings: CYP3A4 inhibition was observed in vitro but not consistently confirmed in small human studies.

症例報告： Almeida & Grimsley (1996) described a semicomatose state in a 54-year-old man after reported kava and alprazolam use. A single case report is a warning signal but does not establish mechanism or frequency.

⚠ 抗精神病薬

Risiko: PROFESSIONAL REVIEW

Individual medical review is appropriate before kava use with antipsychotics:

•Sedation: Additive drowsiness or psychomotor impairment is possible.
•Case reports: Individual reports describe movement disorders; frequency and causality are unclear.
•CYP findings: Laboratory inhibition does not reliably predict the level of a specific medicine.

⚠ 抗凝固薬（血液を薄める薬）

Risiko: PROFESSIONAL REVIEW

Warfarin, phenprocoumon and other anticoagulants require professional review because of their narrow therapeutic window:

•Mechanistic signal: CYP2C9 inhibition was observed in vitro; a clinical kava-warfarin interaction has not been established in controlled studies.
•Monitor INR: Changes in co-used products should be coordinated with the treating clinician.
•Bleeding risk: The baseline risk of anticoagulation makes self-testing inappropriate.

Use kava with anticoagulation only after individual medical review.

中程度のリスクの組み合わせ

以下の組み合わせは注意が必要であり、医師との相談の上でのみ行うべきです。用量調整が必要な場合があります。

抗うつ薬

Risiko: PROFESSIONAL REVIEW

SSRI（フルオキセチン、セルトラリン、パロキセチンなど）：

• Pharmacokinetic interactions may occur depending on the product but are not clinically established as a class
• Serotonin syndrome from kava is not established as a typical clinical effect
• Additive drowsiness or dizziness are possible

SNRI（ベンラファキシン、デュロキセチン）：

• Direct clinical combination data are limited
• Review co-medication individually rather than inferring from in-vitro CYP data

MAO阻害薬：

• MAO-B effects of individual kavalactones have been studied preclinically
• Pawa et al. (2026) found MAO-A inhibition by flavokawain A in an in-vitro enzyme assay; humans and combination with MAO inhibitors were not studied
• Do not self-combine with MAO inhibitors because medicine interactions can be serious
• Obtain medical review before use

抗けいれん薬（抗てんかん薬）

Risiko: PROFESSIONAL REVIEW

フェニトイン、カルバマゼピン、バルプロ酸などの抗けいれん薬：

•Pharmacokinetics: Altered levels are possible but cannot be predicted reliably for individual combinations.
•CNS effects: Additive drowsiness or coordination problems are possible.
•Seizure control: Changes in co-used products belong under professional supervision.

てんかんの場合、カバは医師の監督の下でのみ使用すべきです。

パーキンソン病の薬

Risiko: PROFESSIONAL REVIEW

レボドパとドパミン作動薬：

•Mechanism unclear: Blanket clinical dopamine antagonism by kava has not been established.
•Case reports: Individual reports describe worsening Parkinson symptoms; medical review is therefore needed.

With Parkinson's disease or related medication, use kava only after medical review.

肝毒性の薬

Risiko: 中程度

肝毒性の可能性が知られている薬：

•アセトアミノフェン: 特に高用量で問題になることがあります。
•スタチン: アトルバスタチン、シンバスタチンなど（CYP3A4基質）
•メトトレキサート: 肝毒性の免疫抑制剤
•イソニアジド: 結核治療薬

Additional liver risk is plausible but not quantified for every combination. Potentially hepatotoxic medication requires individual medical review.

相互作用の概要表

物質クラス	例	リスク	メカニズム
アルコール	エタノール	AVOID	Possible additive sedation and impaired coordination; liver risk not quantified
ベンゾジアゼピン	ジアゼパム、ロラゼパム、アルプラゾラム	PROFESSIONAL REVIEW	Possible additive CNS depression; one case report, no controlled combination trials
抗精神病薬	ハロペリドール、オランザピン、クロザピン	PROFESSIONAL REVIEW	Sedation or interactions possible; direct clinical data limited
抗凝固薬	ワルファリン、フェノプロクムン	PROFESSIONAL REVIEW	No controlled kava interaction established; narrow therapeutic window
SSRI	フルオキセチン、セルトラリン、パロキセチン	PROFESSIONAL REVIEW	Possible sedation or pharmacokinetics; no established kava serotonin syndrome
抗けいれん薬	フェニトイン、カルバマゼピン	PROFESSIONAL REVIEW	Possible additive CNS effects and unpredictable pharmacokinetics
パーキンソン病の薬	レボドパ、ドパミン作動薬	PROFESSIONAL REVIEW	Case reports of symptom worsening; no blanket dopamine antagonism established
スタチン	アトルバスタチン、シンバスタチン	PROFESSIONAL REVIEW	Direct clinical interaction data are lacking; review liver and medication context
オピオイド	コデイン、トラマドール、モルヒネ	AVOID / REVIEW	Possible additive CNS depression
カフェイン	コーヒー、エナジードリンク	CAUTION	Human CYP1A2 findings are small and inconsistent

実用的な推奨

カバ摂取前のチェックリスト

1.
薬リストを確認する
すべての現在の薬の相互作用を確認する
2.
医師に相談する
定期的に薬を服用している場合、カバ摂取前に医師の助言を求める
3.
アルコールを避ける
Do not use kava and alcohol together. The main practical reason is possible additive impairment of attention, reaction and coordination; the size of any additional liver risk is not reliably established.
4.
低用量から始める
Do not experiment with a self-selected lower kava dose while taking medicines; obtain professional review of the combination.
5.
症状を観察する
異常な疲労、めまい、または他の症状に注意する

医師および薬剤師への注意

In-vitro CYP findings, small human studies and case reports should be evaluated separately. Additive CNS depression, medicines with a narrow therapeutic window, liver disease and possible product-dependent differences are especially relevant.