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用途
抗生物質，全身用抗菌薬。
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効能
抗生物質, タンパク質合成阻害薬
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説明
An unusual aminoglycoside antibiotic, spectinomycin is produced by fermentation of Streptomyces
spectabil is and differs substantially in its clinical properties from the others. The diaminoinositol unit
(spectinamine) contains two mono-N-methyl groups, and the hydroxyl between them has a stereochemistry
opposite to that in streptomycin. The glycosidically attached sugar also is unusual in that it contains three
consecutive carbonyl groups, either overt or masked, and is fused by two adjacent linkages to spectinamine
to produce an unusual, fused, three-ring structure.
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使用
Spectinomycin finds principal application in the treatment of gonorrhea. It should be noted that the antibiotic resistance among N. gonorrhoeae has caused a number of therapeutic problems. It has been found that only by escalating the antibiotic doses and using probenecid to retard the excretion of penicillin and ampicillin (the drugs of choice) has the continued effective use of penicillin, ampicillin, and tetracycline been possible. Even with modifications in the therapy, from 3 to 8% of cases fail to respond to the usual regimens for uncomplicated gonorrhea. Thus, the treatment of uncomplicated gonorrhea that fails to respond to the usual regimen is spectinomycin therapy.
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定義
ChEBI: An organic heterotricyclic antibiotic that is active against gram-negative bacteria and used (as its dihydrochloride pentahydrate) to treat gonorrhea. It is produced by the bacterium Streptomyces spectabilis.
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抗菌性
Its activity is modest and markedly
affected by medium composition and pH. It exerts only moderate
activity against Gram-positive organisms. It is widely
active against enterobacteria, but Providencia spp. are resistant.
Anaerobic bacteria are also resistant.
Of particular interest is its activity against N. gonorrhoeae,
including β-lactamase-producing strains. Among other sexually
acquired organisms, Ureaplasma urealyticum is susceptible,
but Chlamydia trachomatis and T. pallidum are resistant.
For most organisms, the minimum bactericidal concentration
(MBC) is at least four times the MIC and it is regarded
as essentially bacteristatic. In contrast, it is bactericidal for
gonococci at concentrations close to the MIC, which is of the
order of 2–16 mg/L for both penicillin-susceptible and resistant
strains.
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獲得抵抗性
N. gonorrhoeae strains resistant to spectinomycin have emerged
in South East Asia, the USA and the UK; the resistance of
UK isolates was not attributable to aminoglycoside-modifying
enzymes. In most countries where its use remains low the
prevalence of resistance in gonorrhea is also low.
Acquired resistance in enterobacteria, enterococci and staphylococci
can be caused by nucleotidyltransferases that modify
the drug at position 9. The enzyme from Gram-negative organisms
ANT(3″) (9) also modifies streptomycin at position 3″,
thus conferring cross-resistance to the two drugs. There is no
enzymatic cross-resistance with 2-deoxystreptamine-
containing
aminoglycosides.
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接触アレルゲン
Spectinomycin is an aminocyclitol antibiotic. It is used in human medicine against Neisseria gonorrhoeae and in veterinary medicine, especially for poultry, pigs, and cattle. Cases of dermatitis have been reported in veterinary practice.
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薬物動態学
Cmax 25 mg/kg intramuscular: 60–80 mg/L after 1 h
Plasma half-life: 2–3 h
Volume of distribution: 10–13.4 L
Plasma protein binding: <10%
It is poorly absorbed on oral administration. It is almost completely
excreted unchanged in the urine over 48 h, concentrations
on conventional dosage reaching 1 g/L. Excretion is prolonged in renal impairment, and is unaffected by
probenecid.
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臨床応用
Gonorrhea in penicillin-allergic patients or due to penicillin-resistant
strains (single-dose treatment)
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副作用
Transient headache, dizziness, pain at the site of injection and
occasional fever have been described. No evidence of ototoxicity
or renal toxicity has been found in volunteers receiving
doses of 2 g every 6 h for 3 weeks, amounts much in excess of
those used therapeutically.
