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外観
白色～わずかにうすい黄色, 結晶～粉末
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溶解性
エタノール及びアセトンに溶け、水に溶けにくい。
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解説
解熱鎮痛作用を持つ薬剤。脳内で痛みに関与するシクロオキシゲナーゼ（COX-3）という酵素の働きを阻害する。パラセタモール。化学式C8H9NO2
小学館 デジタル大辞泉について 情報 | 凡例
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用途
アニリン系化合物です。シク ロオキシゲナーゼ（COX）活性を阻害し、プ ロスタグランジン生合成阻害作用を示しま す。
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用途
アニリン系化合物です。シク
ロオキシゲナーゼ（COX）活性を阻害し、プ
ロスタグランジン生合成阻害作用を示しま
す。
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用途
有機合成原料。
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用途
医薬(解熱鎮痛剤)
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効能
鎮痛薬, 解熱薬
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商品名
アセトアミノフェン (マイラン製薬); アセトアミノフェン (丸石製薬); アセトアミノフェン (吉田製薬); アセトアミノフェン (日新製薬－山形); アセトアミノフェン (東洋製薬化成); アセトアミノフェン (東洋製薬化成); アセトアミノフェン (武田テバ薬品); アセトアミノフェン (長生堂製薬); アセトアミノフェン (長生堂製薬); アセリオ (テルモ); アルピニー (久光製薬); アルピニー (久光製薬); アンヒバ (マイランEPD); カロナール (あゆみ製薬); カロナール (あゆみ製薬); カロナール (あゆみ製薬); カロナール (あゆみ製薬); パラセタ (シオエ製薬); ピレチノール (岩城製薬)
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説明
Acetaminophen differs from the nonsteroidal anti-inflammatory agents described in that it
is devoid of anti-inflammatory and antirheumatic properties. It was recently shown that
acetaminophen, like aspirin, inhibits cyclooxygenase action in the brain and is even
stronger than aspirin. On the other hand, the mechanism of analgesic action of acetaminophen is not fully clear, since it acts poorly on peripheral cyclooxygenase.
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化学的特性
White Solid
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使用
Acetaminophen is widely used as an analgesic and fever-reducing agent. Acetaminophen is
designed for moderate analgesia. It is also effective like aspirin and is used in analgesia for
headaches (from weak to moderate pain), myalgia, arthralgia, chronic pain, for oncological and
post-operational pain, etc.
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適応症
Acetaminophen (Tylenol) is an effective antipyretic and
analgesic that is well tolerated at therapeutic doses. It
has only weak antiinflammatory activity; thus, it is not
useful in the treatment of rheumatoid arthritis and
other inflammatory conditions.
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世界保健機関（WHO）
Paracetamol, a widely used analgesic and antipyretic is known, in
case of overdose, to cause liver damage, frequently with fatal outcome. In
recommended dosages this risk does not occur. Paracetamol is listed in the WHO
Model List of Essential Drugs.
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一般的な説明
Odorless white crystalline solid. Bitter taste. pH (saturated aqueous solution) about 6.
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空気と水の反応
Slightly soluble in water.
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反応プロフィール
Acetaminophen is sensitive to light. Incompatible with strong oxidizers.
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火災危険
Flash point data for Acetaminophen are not available; however, Acetaminophen is probably combustible.
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生物活性
Cyclooxygenase inhibitor; may be selective for COX-3 (IC 50 values are 460, > 1000 and > 1000 μ M for canine COX-3, and murine COX-1 and COX-2 respectively). Widely used analgesic and antipyretic agent.
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作用機序
The mechanism of action of paracetamol is not well understood, but it may
act in a similar fashion to NSAIDs, with inhibition of cyclo-oxygenase
enzymes COX-1 and COX-2 to reduce the phenoxyl radical
formation required for COX-1 and 2 activity and prostaglandin synthesis. I t
has selectivity for inhibition of prostaglandin synthesis with low
concentrations of peroxidases and arachidonic acid, but limited effect at
higher concentrations and, therefore, has limited anti-inflammatory effects.
Unlike opioids, paracetamol has no well-defined endogenous binding sites.
I n some circumstances, it may exhibit a preferential effect on COX-2
inhibition. There is growing evidence of a central antinociceptive effect of
paracetamol. It has also been found to prevent prostaglandin production at
the cellular transcriptional concentration, independent of COX activity.
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薬物動態学
Paracetamol is absorbed rapidly from the small intestine after oral
administration; peak plasma concentrations are reached after 30–60min. It
may also be given rectally and intravenously (either as paracetamol or the
prodrug propacetamol). It has good oral bioavailability (70%–90%); rectal absorption is more variable (bioavailability ~50%–80%) with a longer time to
reach peak plasma concentration. The plasma half-life is approximately 2–3 h.
Paracetamol is metabolised by hepatic microsomal enzymes mainly to the
glucuronide, sulphate and cysteine conjugates. None of these metabolites is
pharmacologically active. Aminimal amount of the metabolite N-acetyl-pamino-
benzoquinone imine is normally produced by cytochrome P450–
mediated hydroxylation. This reactive toxic metabolite is rendered harmless
by conjugation with liver glutathione, then excreted renally as mercapturic
derivatives. With larger doses of paracetamol, the rate of formation of the
reactive metabolite exceeds that of glutathione conjugation, and the reactive
metabolite combines with hepatocellular macromolecules, resulting in cell
death and potentially fatal hepatic failure. The formation of this metabolite is
increased by drugs inducing cytochrome P450 enzymes, such as barbiturates
or carbamazepine.
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臨床応用
Acetaminophen is weakly acidic (pKa = 9.51) and synthesized by the acetylation of p-aminophenol. It is weakly bound
to plasma proteins (18–25%). Acetaminophen is indicated for use as an antipyretic/analgetic, particularly in those
individuals displaying an allergy or sensitivity to aspirin. It does not possess anti-inflammatory activity, but it will
produce analgesia in a wide variety of arthritic and musculoskeletal disorders. It is available in various formulations,
including suppositories, tablets, capsules, granules, and solutions. The usual adult dose is 325 to 650 mg every 4 to
6 hours. Doses of greater than 2.6 g/day are not recommended for long-term therapy because of potential
hepatotoxicity issues. Acetaminophen, unlike aspirin, is stable in aqueous solution, making liquid formulations readily
available, a particular advantage in pediatric cases.
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代謝経路
Acetaminophen (APAP) is metabolized by mice, and
nine metabolites are identified in the urine. The main
metabolites are APAP-glucuronide and 3-cysteinyl-
APAP. Hydroquinone metabolites of S-(2,5-
dihydroxyphenyl)cysteine and S-(2,5-dihydroxyphenyl)-
N-acetylcysteine result from the benzoquinone
metabolite of APAP.
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代謝
acetaminophen is undergoes rapid first-pass metabolism in the GI tract primarily by conjugation reactions, with the
O-sulfate conjugate being the primary metabolite in children and the O-glucuronide being the primary metabolite in
adults. A minor, but significant, product of both acetaminophen and phenacetin is the N-hydroxyamide produced by a
CYP2E1 and CYP3A4.
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純化方法
Recrystallise Paracetamol from water or EtOH. The 3,5-dinitrobenzamide complex gives orange crystals from hot H2O and has m 171.5o. [Beilstein 13 H 460, 13 I 159, 13 II 243, 13 III 1056, 13 IV 1091.]
