Amoxicillin

Acute otitis media

Children with acute otitis media who are younger than six months of age are generally treated with amoxicillin or other antibiotics. Although most children with acute otitis media who are older than two years old do not benefit from treatment with amoxicillin or other antibiotics, such treatment may be helpful in children younger than two years old with acute otitis media that is bilateral or accompanied by ear drainage.[18] In the past, amoxicillin was dosed three times daily when used to treat acute otitis media, which resulted in missed doses in routine ambulatory practice. There is now evidence that two-times daily dosing or once-daily dosing has similar effectiveness.[19]

Respiratory infections

Most sinusitis infections are caused by viruses, for which amoxicillin and amoxicillin-clavulanate are ineffective,[20] and the small benefit gained by amoxicillin may be overridden by the adverse effects.[21] Amoxicillin is considered the first-line empirical treatment for most cases of uncomplicated bacterial sinusitis in children and adults when culture data is unavailable.[22][23][24] Amoxicillin is recommended as the preferred first-line treatment for community-acquired pneumonia in adults by the National Institute for Health and Care Excellence, either alone (mild to moderate severity disease) or in combination with a macrolide.[25] Research suggests that is as effective as co-amoxiclav (a broad-spectrum antibiotic) for people admitted to hospital with pneumonia, regardless of its severity.[26][27] The World Health Organization (WHO) recommends amoxicillin as first-line treatment for pneumonia that is not "severe".[28] Amoxicillin is used in post-exposure inhalation of anthrax to prevent disease progression and for prophylaxis.[17]

H. pylori

It is effective as one part of a multi-drug regimen for the treatment of stomach infections of Helicobacter pylori. It is typically combined with a proton-pump inhibitor (such as omeprazole) and a macrolide antibiotic (such as clarithromycin); other drug combinations are also effective.[29] One old article suggests using amoxicillin with bismuth subsalicylate (pepto bismol) which does work.[30]

Lyme borreliosis

Amoxicillin is effective for the treatment of early cutaneous Lyme borreliosis; the effectiveness and safety of oral amoxicillin is neither better nor worse than common alternatively-used antibiotics.[31]

Odontogenic infections

Amoxicillin is used to treat odontogenic infections, infections of the tongue, lips, and other oral tissues. It may be prescribed following a tooth extraction, particularly in those with compromised immune systems.[32]

Skin infections

Amoxicillin is occasionally used for the treatment of skin infections,[17] such as acne vulgaris.[33] It is often an effective treatment for cases of acne vulgaris that have responded poorly to other antibiotics, such as doxycycline and minocycline.[34]

Infections in infants in resource-limited settings

Amoxicillin is recommended by the World Health Organization for the treatment of infants with signs and symptoms of pneumonia in resource-limited situations when the parents are unable or unwilling to accept hospitalization of the child. Amoxicillin in combination with gentamicin is recommended for the treatment of infants with signs of other severe infections when hospitalization is not an option.[35]

Prevention of bacterial endocarditis

It is also used to prevent bacterial endocarditis and as a pain-reliever in high-risk people having dental work done, to prevent Streptococcus pneumoniae and other encapsulated bacterial infections in those without spleens, people with damaged spleens (such as some with sickle-cell disease), and for both the prevention and the treatment of anthrax.[8] The United Kingdom recommends against its use for infectious endocarditis prophylaxis.[36] These recommendations do not appear to have changed the rates of infection for infectious endocarditis.[37]

Combination treatment

Amoxicillin is susceptible to degradation by β-lactamase-producing bacteria, which are resistant to most β-lactam antibiotics, such as penicillin. For this reason, it may be combined with clavulanic acid, a β-lactamase inhibitor. This drug combination is commonly called co-amoxiclav.[38]

Spectrum of activity

It is a moderate-spectrum, bacteriolytic, β-lactam antibiotic in the aminopenicillin family used to treat susceptible Gram-positive and Gram-negative bacteria. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other β-lactam antibiotics. In general, Streptococcus, Bacillus subtilis, Enterococcus, Haemophilus, Helicobacter, and Moraxella are susceptible to amoxicillin, whereas Citrobacter, Klebsiella and Pseudomonas aeruginosa are resistant to it.[39] Some E. coli and most clinical strains of Staphylococcus aureus have developed resistance to amoxicillin to varying degrees.[40]

Nonallergic 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 and may rarely be a component of the DRESS syndrome.[48]

The rash is described as maculopapular or morbilliform (measles-like; therefore, in medical literature, it is called "amoxicillin-induced morbilliform rash".[49]). 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.[50][51]

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.[52]

Economics

Amoxicillin is relatively inexpensive.[70] In 2022, a survey of eight generic antibiotics commonly prescribed in the United States found their average cost to be about $42.67, while amoxicillin was sold for $12.14 on average.[71]

Modes of delivery

Pharmaceutical manufacturers make amoxicillin in trihydrate form, for oral use available as capsules, regular, chewable and dispersible tablets, syrup and pediatric suspension for oral use, and as the sodium salt for intravenous administration.

An extended-release is available.[5][72] The intravenous form of amoxicillin is not sold in the United States.[73] When an intravenous aminopenicillin is required in the United States, ampicillin is typically used. When there is an adequate response to ampicillin, the course of antibiotic therapy may often be completed with oral amoxicillin.[74]

Research with mice indicated successful delivery using intraperitoneally injected amoxicillin-bearing microparticles.[75]

Names

Amoxicillin is the international nonproprietary name (INN),[76] British Approved Name (BAN), Australian Approved Name (AAN), and United States Adopted Name (USAN), while amoxycillin is the former AAN.[77]

Amoxicillin is one of the semisynthetic penicillins discovered by the former pharmaceutical company Beecham Group. The patent for amoxicillin has expired, thus amoxicillin and co-amoxiclav preparations are marketed under various brand names across the world.[78]