methicillin
American Heritage Dictionary:
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meth·i·cil·lin
(mĕth'ĭ-sĭl'ĭn) 
n.
A synthetic antibiotic, C17H19N2O6NaS, related to penicillin and most commonly used in treatment of infections caused by penicillinase-producing staphylococci.
n.
A synthetic antibiotic, C17H19N2O6NaS, related to penicillin and most commonly used in treatment of infections caused by penicillinase-producing staphylococci.
[METH- + (PEN)ICILLIN.]
American Heritage Stedman's Medical Dictionary:
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meth·i·cil·lin
(mĕth'ĭ-sĭl'ĭn)
n.
n.
A synthetic antibiotic related to penicillin and most commonly used in treatment of infections caused by staphylococci that produce penicillinase.
Oxford Dictionary of Biochemistry:
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meticillin
(sodium) or methicillin
a semisynthetic antibiotic of the penicillin type that is lactamase resistant.
a semisynthetic antibiotic of the penicillin type that is lactamase resistant.
| methyne, methyltransferase, methylthioribose | |
| metmyoglobin, metre, metre-kilogram-second system |
Saunders Veterinary Dictionary:
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methicillin
A semisynthetic penicillin which is highly resistant to inactivation by penicillinase; its sodium salt is used parenterally.
Wikipedia on Answers.com:
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Meticillin
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|---|---|
| Systematic (IUPAC) name | |
| (2S,5R,6R)-6-[(2,6-dimethoxybenzoyl)amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid | |
| Clinical data | |
| Pregnancy cat. | ? |
| Legal status | ? |
| Routes | IV |
| Pharmacokinetic data | |
| Bioavailability | Not orally absorbed |
| Metabolism | hepatic, 20–40% |
| Half-life | 25–60 minutes |
| Excretion | renal |
| Identifiers | |
| CAS number | 61-32-5  |
| ATC code | J01CF03 QJ51CF03 |
| PubChem | CID 6087 |
| DrugBank | DB01603 |
| ChemSpider | 5862  |
| UNII | Q91FH1328A |
| ChEMBL | CHEMBL575 |
| Chemical data | |
| Formula | C17H20N2O6S |
| Mol. mass | 380.42 g/mol |
| SMILES | eMolecules & PubChem |
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Meticillin (INN, BAN) or methicillin (USAN) is a narrow-spectrum beta-lactam antibiotic of the penicillin class. It should not be confused with the antibiotic metacycline.
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Contents
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History
Methicillin was developed by Beecham in 1959.[1] It was previously used to treat infections caused by susceptible Gram-positive bacteria, in particular, beta-lactamase-producing organisms such as Staphylococcus aureus that would otherwise be resistant to most penicillins, but it is no longer clinically used.
Its role in therapy has been largely replaced by flucloxacillin and dicloxacillin, however the term methicillin-resistant Staphylococcus aureus (MRSA) continues to be used to describe Staphylococcus aureus strains resistant to all penicillins.
Methicillin is no longer manufactured because the more stable and similar penicillins such as oxacillin (used for clinical antimicrobial susceptibility testing), flucloxacillin, and dicloxacillin are used medically.
Mode of action
Main article: Beta-lactam antibiotic
Like other beta-lactam antibiotics, methicillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. It does this by binding to and competitively inhibiting the transpeptidase enzyme used by bacteria to cross-link the peptide (D-alanyl-alanine) used in peptidoglycan synthesis. Methicillin and other beta-lactam antibiotics are structural analogs of D-alanyl-alanine, and the transpeptidase enzymes that bind to them are sometimes called penicillin-binding proteins (PBPs). [2]
Medicinal chemistry
Methicillin is insensitive to beta-lactamase (also known as penicillinase) enzymes secreted by many penicillin-resistant bacteria. The presence of the ortho-dimethoxyphenyl group directly attached to the side-chain carbonyl group of the penicillin nucleus facilitates the β-lactamase resistance, since those enzymes are relatively intolerant of side-chain steric hindrance. Thus, it is able to bind to penicillin-binding proteins (PBPs) and inhibit peptidoglycan crosslinking, but it is not bound by or inactivated by β-lactamases.
Clinical use
Methicillin is no longer used to treat patients. Compared to other beta-lactamase-resistant penicillins, it is less active, can be administered only parenterally, and has a higher frequency of interstitial nephritis, an otherwise-rare side-effect of penicillins. But it serves a purpose in the laboratory to determine the antibiotic sensitivity of Staphylococcus aureus to other beta-lactamase-resistant penicillins.
References
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Wikinews has related news: Supergerm deaths soar, surpass AIDS in the United States |
- ^ Graham Dutfield (30 July 2009). Intellectual property rights and the life science industries: past, present and future. World Scientific. pp. 140–. ISBN 978-981-283-227-6. http://books.google.com/books?id=hnleY38aUxYC&pg=PA140. Retrieved 18 November 2010.
- ^ Gladwin M., Trattler B. Clinical Microbiology made ridiculously simple. 3rd edition. Miami: MedMaster, Inc.; 2004.
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Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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American Heritage Stedman's Medical Dictionary
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.
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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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