Amoxicillin

Amoxicillin Systematic (IUPAC) name (2S,5R,6R)- 6-{[(2R)-2-amino- 2-(4-hydroxyphenyl)- acetyl]amino}- 3,3-dimethyl- 7-oxo- 4-thia- 1-azabicyclo[3.2.0]heptane- 2-carboxylic acid Identifiers CAS number 26787-78-0 ATC code J01CA04 QG51AX01 PubChem CID 33613 DrugBank DB01060 ChemSpider 31006 Chemical data Formula C16H19N3O5S  Mol. mass 365.4 g/mol SMILES eMolecules & PubChem Pharmacokinetic data Bioavailability 95% oral Metabolism less than 30% biotransformed in liver Half-life 61.3 minutes Excretion renal Therapeutic considerations Pregnancy cat. A(AU) B(US) Legal status POM (UK) Routes Oral, intravenous  Y(what is this?)  (verify)

Amoxicillin BP

Amoxicillin (INN), formerly amoxycillin (BAN), amoxycillin (cilamox) in Australia^[1], abbreviated Amox,Tormoxin (in India), is a moderate-spectrum, bacteriolytic, β-lactam antibiotic used to treat bacterial infections caused by susceptible microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other β-lactam antibiotics. It is also a treatment for cystic acne.^[2]

Amoxicillin is susceptible to degradation by β-lactamase-producing bacteria, and so may be given with clavulanic acid to decrease its susceptibility.

Mode of action

Amoxicillin acts by inhibiting the synthesis of bacterial cell wall. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell walls of both Gram-positive and Gram-negative bacteria

Formulations

Amoxicillin in trihydrate form is available as capsules, chewable and dispersible tablets plus syrup and pediatric suspension for oral use, and as the sodium salt for intravenous administration (although the IV formulation is not available in the United States^[3]). It is one of the most common antibiotics prescribed for children, and the liquid forms are helpful where the patient might find it difficult to take tablets or capsules. It has three ionizable groups. A once daily dosing form (Moxatag) was approved by the American FDA in January 2008.

Side effects

Side effects are as those for other beta-lactam antibiotics. Side effects include nausea, vomiting, rashes, and antibiotic-associated colitis. Loose bowel movements (diarrhea) also may occur. Rarer but patient reported side effects include mental changes, lightheadedness, confusion, suicidal thoughts, depression, anxiety, sensitivity to lights and sounds, unclear thinking. Immediate medical care is required upon the first signs of these side effects.

The onset of an allergic reaction to amoxicillin can be very sudden and intense - emergency medical attention must be sought as quickly as possible. The initial onset of such a reaction often starts with a change in mental state; skin rash with intense itching (often beginning in fingertips and around groin area and rapidly spreading) and sensations of fever, nausea, and vomiting. Any other symptoms that seem even remotely suspicious must be taken very seriously.

Use of the amoxicillin/clavulanic acid combination for more than one week has caused moderate to severe hepatitis in a number of patients. Young children who ingested acute overdoses of amoxicillin manifested lethargy, vomiting and renal dysfunction.^[4][5]

Non-allergic amoxicillin rash

Somewhere between 3% to 10% of children taking amoxicillin (or ampicillin) show a late-developing (>72 hours after beginning medication and having never taken penicillin-like medication previously) often itchy rash [2][3], which is sometimes referred to as the "amoxicillin rash." The rash can also occur in adults.

The rash is described as maculopapular or morbilliform (measles-like; therefore, in medical literature, "amoxicillin-induced morbilliform rash"^[6]). It starts on the trunk and can spread from there. This rash is unlikely to be a true allergic reaction, and is not a contra-indication for future amoxicillin usage, nor should current regimen necessarily be stopped. However, as mentioned above, this common amoxicillin rash and a dangerous allergic reaction cannot easily be distinguished by inexperienced persons, and therefore a health professional should be consulted if a rash develops. (Pichichero, 2005; Schmitt 2005)

A non-allergic amoxicillin rash may also be an indicator of infectious mononucleosis: Some studies indicate that approximately 80-90% of patients with acute Epstein Barr virus infection treated with amoxicillin or ampicillin develop such a rash.^[7]

Non-allergic amoxicillin rash 8 days after first dose, 24 hours after rash began. Diagnosed by pediatric resident at local university hospital.

8 hours after first photo. Individual spots have grown and begun to merge.

23 hours after first photo. Color apparently fading, much of rash has spread to confluence.

Proprietary preparations

Amoxicillin is one of the semi-synthetic penicillins discovered by Beecham scientists. The patent for amoxicillin has expired, thus amoxicillin is marketed under many trade names, including:', Actimoxi, Alphamox, Amocla, AMK, Amoksibos, Amoxiclav Sandoz, Amoxidal, Amoxil, Amoxin, Amoksiklav, Amoxibiotic, Amoxicilina, Apo-Amoxi, Augmentin (with clavulanic acid), Bactox, Betalaktam, Cilamox, Curam, Dedoxil, Dispermox, Duomox, E-Mox, Enhancin, Gimalxina, Geramox, Hiconcil, Isimoxin, Klavox, Lamoxy, Moxatag, Moxilen, Moxypen, Moxyvit, Nobactam, Novamoxin, Ospamox, Panklav, Pamoxicillin, Panamox, Polymox, Samthongcillin, Clamoxyl, Senox, Sinacilin, Trimox, Tolodina, Tormoxin (India), Wymox, Yucla, Zerrsox and Zimox.

References

• Middlebrook Pharmaceuticals (March 2009). "MiddleBrook Pharmaceuticals Launches MOXATAG(TM), the First and Only FDA-Approved Once-Daily Amoxicillin". http://www.middlebrookpharma.com/releasedetail.cfm?ReleaseID=427462. 
• GlaxoSmithKline (February 2006). "Amoxil - Prescribing information" (PDF). http://us.gsk.com/products/assets/us_amoxil.pdf. 
• Neal, M. J. (2002). Medical pharmacology at a glance (4th ed.). Oxford: Blackwell Science. ISBN 0-632-05244-9. 
• Pichichero ME (April 2005). "A review of evidence supporting the American Academy of Pediatrics recommendation for prescribing cephalosporin antibiotics for penicillin-allergic patients". Pediatrics 115 (4): 1048–57. doi:10.1542/peds.2004-1276. PMID 15805383. http://pediatrics.aappublications.org/cgi/content/full/115/4/1048. 
• Schmitt, Barton D. (2005). Your child's health: the parents' one-stop reference guide to symptoms, emergencies, common illnesses, behavior problems, healthy development (2nd ed.). New York: Bantam Books. ISBN 0-553-38369-8. 
• British National Formulary 45 March 2003

Footnotes

External links

• University of Michigan Mott's Children's Hospital article about "amoxicillin rash." (Very similar to Schmitt 2005 content)
• Amoxicillin Side Effect Experiences
• U.S. National Library of Medicine: Drug Information Portal - Amoxicillin