医師の一分

アクセスカウンタ

zoom RSS 緑茶が降圧剤ナドロールの効果を妨げる

<<   作成日時 : 2014/01/18 22:39   >>

ブログ気持玉 0 / トラックバック 0 / コメント 0

緑茶が降圧剤ナドロールの効果を妨げる
β遮断薬の吸収を助ける特別なトランスポーターを阻害するために血中濃度が低下してしまうという。

-----------------------------------------------------
14 January 2014 Last updated at 01:39 GMT
Green tea 'can impede nadolol blood pressure medicine'
By Michelle Roberts
Health editor, BBC News online
http://www.bbc.co.uk/news/health-25716708

Green tea can weaken the effects of a commonly prescribed blood pressure pill, experts warn.

Japanese researchers found the herbal drink blocks special cell transporters that normally help the body absorb the beta-blocker medicine.
In tests, people who drank green tea alongside taking their tablets ended up with lower circulating blood levels of the drug nadolol.
Experts say consumers need to be aware of this interaction.
Like other drugs, the patient leaflet accompanying nadolol tablets warns that certain medicines, including herbal remedies, can interact with their action. But it does not include green tea in this list.
Doctors already advise that certain fruit juices, including grapefruit, can interfere with some common medications, including beta blockers.
The study in the journal Clinical Pharmacology & Therapeutics found nadolol's lowering effect on blood pressure was blunted in the 10 volunteers who agreed to drink green tea.
Follow-up tests in the laboratory revealed that green tea blocked a drug transporter present in the lining of the human gut that helps move nadolol into the cells.

Weakening effect
The scientists estimate that a couple of cups of green tea would be enough to have this effect in humans.
It is not clear if other types of tea have a similar effect.
And they point out that green tea is also purported to have many health benefits.
Green tea is less processed than other teas and, consequently, retains higher concentrations of antioxidants.
Sotiris Antoniou, Royal Pharmaceutical Society spokesman and a consultant pharmacist in cardiovascular medicine, suggested to blood pressure patients who still want to drink green tea that leaving a four-hour gap between cups and taking their medicines might get round the problem.
He said: "This has yet to be confirmed and is only extrapolated from our experience with grapefruit for this type of interaction.
"What is clear as healthcare providers is that we need to ask patients about their consumption of various fruits and supplements such as grapefruit and green tea, and this needs to be documented in the clinical notes, and where appropriate provide information on avoiding green tea or grapefruit, or better where possible to prescribe an alternative drug that is not affected by the consumption of green tea.
Mr Antoniou added: "For any individual concerned, they can go to their local community pharmacy where they can clarify any potential interaction."


-----------------------------------------------------
Clinical Pharmacology & Therapeutics (13 January 2014) | doi:10.1038/clpt.2013.241

Green tea ingestion greatly reduces plasma concentrations of nadolol in healthy subjects

S Misaka, J Yatabe, F Muller, K Takano, K Kawabe, H Glaeser, MS Yatabe, S Onoue, JP Werba, H Watanabe, S Yamada, MF Fromm and J Kimura

Abstract
This study aimed at evaluating effects of green tea on pharmacokinetics and pharmacodynamics of the β-blocker nadolol. Ten healthy volunteers received a single oral dose of 30?mg nadolol with green tea or water after repeated consumption of green tea (700?mL/day) or water for 14 days. Catechin concentrations in green tea and plasma were determined. Green tea markedly decreased Cmax and AUC0-48 of nadolol by 85.3% and 85.0%, respectively (P < 0.01) without altering renal clearance of nadolol. Nadolol effects on systolic blood pressure were significantly reduced by green tea. [3H]Nadolol uptake assays in HEK293 cells stably expressing OATP1A2 or OATP2B1 revealed that nadolol was a substrate of OATP1A2 (Km=84.3 μM), but not of OATP2B1. Moreover, green tea significantly inhibited OATP1A2-mediated nadolol uptake (IC50=1.36%). These results suggest that green tea reduces plasma concentrations of nadolol possibly in part by inhibition of OATP1A2-mediated uptake of nadolol in the intestine.

テーマ

関連テーマ 一覧


月別リンク

ブログ気持玉

クリックして気持ちを伝えよう!
ログインしてクリックすれば、自分のブログへのリンクが付きます。
→ログインへ

トラックバック(0件)

タイトル (本文) ブログ名/日時

トラックバック用URL help


自分のブログにトラックバック記事作成(会員用) help

タイトル
本 文

コメント(0件)

内 容 ニックネーム/日時

コメントする help

ニックネーム
本 文
緑茶が降圧剤ナドロールの効果を妨げる 医師の一分/BIGLOBEウェブリブログ
文字サイズ:       閉じる