|Systematic (IUPAC) name|
|Trade names||Actimoxi, Alphamox, Amocla,Tycil, Amoxil, Trimox, among others|
|Pregnancy cat.||A (AU) B (US)|
|Legal status||POM (UK) ℞-only (US)|
|Metabolism||less than 30% biotransformed in liver|
|ATC code||J01 QG51|
|Mol. mass||365.4 g/mol|
|(what is this?)|
Amoxicillin (INN), formerly amoxycillin (BAN), and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam antibiotic in the aminopenicillin family 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. Amoxicillin is one of the most common antibiotics prescribed for children. The drug first became available in 1972.
Amoxicillin is susceptible to degradation by β-lactamase-producing bacteria, which are resistant to a narrow spectrum of β-lactam antibiotics, such as penicillin. For this reason, it is often combined with clavulanic acid, a β-lactamase inhibitor. This increases effectiveness by reducing its susceptibility to β-lactamase resistance.
Amoxicillin is used in the treatment of a number of infections, including acute otitis media, streptococcal pharyngitis, pneumonia, skin infections, urinary tract infections, Salmonella infections, Lyme disease, and chlamydia infections. It is also used to prevent bacterial endocarditis in high-risk people having dental work done, to prevent Streptococcus pneumoniae and other encapsulated bacterial infections in those without spleens, such as people with sickle-cell disease, and for both the prevention and the treatment of anthrax. The United Kingdom recommends against its use for infectious endocarditis prophylaxis. These recommendations have not appeared to have changed the rates of infection.
Amoxicillin and amoxicillin-clavulanate are recommended by guidelines as the first-choice drug for bacterial sinusitis, but most sinusitis is caused by viruses, for which amoxicillin and amoxicillin-clavulanate are ineffective. Amoxicillin is occasionally used for the treatment of skin infections, such as acne vulgaris. It is often an effective treatment for cases of acne vulgaris that have responded poorly to other antibiotics, such as doxycycline and minocycline.
Side-effects are similar to those for other beta-lactam antibiotics, including nausea, vomiting, rashes, and antibiotic-associated colitis. Loose bowel movements (diarrhea) may also occur. Rarer side-effects include mental changes, lightheadedness, insomnia, confusion, anxiety, sensitivity to lights and sounds, and 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 phase 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. However, more mild allergy symptoms, such as a rash, can occur at any time during treatment, even up to a week after treatment has ceased. For some people allergic to amoxicillin, the side-effects can be deadly.
Use of the amoxicillin/clavulanic acid combination for more than one week has caused mild hepatitis in some patients. Young children having ingested acute overdoses of amoxicillin-manifested lethargy, vomiting, and renal dysfunction.
Nonallergic amoxicillin rash
Between 3 and 10% of children taking amoxicillin (or ampicillin) show a late-developing (>72 hours after beginning medication and having never taken penicillin-like medication previously) rash, 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, it is called "amoxicillin-induced morbilliform rash".) It starts on the trunk and can spread from there. This rash is unlikely to be a true allergic reaction, and is not a contraindication for future amoxicillin usage, nor should the current regimen necessarily be stopped. However, this common amoxicillin rash and a dangerous allergic reaction cannot easily be distinguished by inexperienced persons, so a healthcare professional is often required to distinguish between the two.
A nonallergic amoxicillin rash may also be an indicator of infectious mononucleosis. Some studies indicate about 80-90% of patients with acute Epstein Barr virus infection treated with amoxicillin or ampicillin develop such a rash.
Amoxicillin may interact with these drugs:
- Anticoagulants (e.g., warfarin, pradaxa)
- Allopurinol (gout treatment)
- Certain antibiotics
- Cancer treatment (methotrexate)
- Uricosuric drugs
- Typhoid vaccine
Mechanism of action
This drug 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 walls of both Gram-positive and Gram-negative bacteria.
It has two ionizable groups in the physiological range (the amino group in alpha-position to the amide carbonyl group and the carboxyl group).
Spectrum of microorganism susceptibility and resistance
In general, Streptococcus, Bacillus subtilis, Enterococcus, Haemophilus, Helicobacter, and Moraxella are susceptible to amoxicillin, whereas Citrobacter, Klebsiella and Pseudomonas aeruginosa are resistant to it. Some E. coli and most clinical isolates of Staphylococcus aureus have developed resistance to amoxicillin to varying degrees.
Amoxicillin was one of several semisynthetic derivatives of 6-aminopenicillanic acid (6-APA) developed at Beecham in the 1960s. It became available in 1972, and was the second aminopenicillin to reach the market (after ampicillin in 1961). Co-amoxiclav became available in 1981.
Modes of delivery
Pharmaceutical manufacturers make amoxicillin in trihydrate form, available as capsules, chewable and dispersible tablets, syrup and pediatric suspension for oral use, and as the sodium salt for intravenous administration.
Amoxicillin is most commonly taken orally. The liquid forms are helpful where the patient might find it difficult to take tablets or capsules.
Amoxicillin is one of the semisynthetic penicillins discovered by Beecham scientists. The patent for amoxicillin has expired, thus amoxicillin and co-amoxiclav preparations are marketed under many trade names and/or have several synonyms across the world, such as:
- Senox 
Names without individual reference are referenced at.
- "Amoxicillin Susceptibility and Resistance Data". Retrieved 20 July 2013.
- "Amoxicillin". The American Society of Health-System Pharmacists. Retrieved 3 April 2011.
- "CG64 Prophylaxis against infective endocarditis: Full guidance". NICE. Retrieved 8 June 2011.
- Thornhill, MH; Dayer, MJ, Forde, JM, Corey, GR, Chu, VH, Couper, DJ, Lockhart, PB (2011-05-03). "Impact of the NICE guideline recommending cessation of antibiotic prophylaxis for prevention of infective endocarditis: before and after study". BMJ (Clinical research ed.) 342: d2392. doi:10.1136/bmj.d2392. PMC 3086390. PMID 21540258.
- American Academy of Allergy, Asthma, and Immunology. "Five Things Physicians and Patients Should Question". Choosing Wisely: an initiative of the ABIM Foundation (American Academy of Allergy, Asthma, and Immunology). Retrieved August 14, 2012.
- Ahovuo-Saloranta, A.; Rautakorpi, U. M.; Borisenko, O. V.; Liira, H.; Williams Jr, J. W.; Mäkelä, M. (2008). "Antibiotics for acute maxillary sinusitis". In Ahovuo-Saloranta, Anneli. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.CD000243.pub2.
- "Adolescent Acne: Management".
- "Amoxicillin and Acne Vulgaris". scienceofacne.com. 2012-09-05. Retrieved 2012-08-17.
- Cundiff j, Joe S.; Joe, S (2007). "Amoxicillin-clavulanic acid-induced hepatitis". Amer. J. Otolaryngol. 28 (1): 28–30. doi:10.1016/j.amjoto.2006.06.007. PMID 17162128.
- R. Baselt (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, CA: Biomedical Publications. pp. 81–83.
- "Role of delayed cellular hypersensitivity and adhesion molecules in amoxicillin-induced morbilliform rashes". Cat.inist.fr. Retrieved 2010-11-13.
- 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.
- 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.
- Kagan, B (1977). "Ampicillin rash". Western Journal of Medicine 126 (4): 333–335. PMC 1237570. PMID 855325.
- British National Formulary 57 March 2009
- "Amoxicillin spectrum of bacterial susceptibility and Resistance". Retrieved 8 April 2012.
- Raviña, E (2011). The Evolution of Drug Discovery. Weinheim: Wiley-VCH. p. 262. ISBN 9783527326693.
- Bruggink, A (2001). Synthesis of β-lactam antibiotics. Springer. p. 17. ISBN 0-7923-7060-0.
- Farazuddin, Mohammad; Chauhan, Arun; Khan, Raza M.M.; Owais, Mohammad (2011). "Amoxicillin-bearing microparticles: potential in the treatment of Listeria monocytogenes infection in Swiss albino mice". Bioscience Reports 31 (4): 265–72. doi:10.1042/BSR20100027. PMID 20687896.
- Catalog.md: Actimoxi Linked 2013-12-09
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- DrugsUpdate India: Defender from Sac Pharma Linked 2013-12-09
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- PakMediNet (Pakistan): Zoxicillin Linked 2013-12-09
- Drugs.com: Amoxicillin Linked 2013-12-09
- Neal, M. J. (2002). Medical pharmacology at a glance (4th ed.). Oxford: Blackwell Science. ISBN 0-632-05244-9.
- British National Formulary 45 March 2003
- University of Michigan Mott's Children's Hospital article about "amoxicillin rash."[dead link] (Very similar to Schmitt 2005 content)[dead link]
- U.S. National Library of Medicine: Drug Information Portal - Amoxicillin