Amoxicillin
Overview
 
Amoxicillin formerly amoxycillin (BAN
British Approved Name
A British Approved Name is the official non-proprietary or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia...

), and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam
Beta-lactam antibiotic
β-Lactam antibiotics are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in its molecular structure. This includes penicillin derivatives , cephalosporins , monobactams, and carbapenems...

 antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 used to treat bacterial infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

s caused by susceptible microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s. 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 antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s prescribed for children.

Amoxicillin is susceptible to degradation by β-lactamase
Beta-lactamase
Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems . These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam...

-producing bacteria, which are resistant to a broad spectrum of β-lactam antibiotics, such as penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

.
Encyclopedia
Amoxicillin formerly amoxycillin (BAN
British Approved Name
A British Approved Name is the official non-proprietary or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia...

), and abbreviated amox, is a moderate-spectrum, bacteriolytic, β-lactam
Beta-lactam antibiotic
β-Lactam antibiotics are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in its molecular structure. This includes penicillin derivatives , cephalosporins , monobactams, and carbapenems...

 antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 used to treat bacterial infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

s caused by susceptible microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s. 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 antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s prescribed for children.

Amoxicillin is susceptible to degradation by β-lactamase
Beta-lactamase
Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems . These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam...

-producing bacteria, which are resistant to a broad spectrum of β-lactam antibiotics, such as penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....

. For this reason, it is often combined with clavulanic acid
Clavulanic acid
Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...

, a β-lactamase inhibitor, and marketed under one name. This increases effectiveness by reducing its susceptibility to β-lactamase resistance.

Medical uses

Amoxicillin is used in the treatment of a number of infections including: acute otitis media, streptococcal pharyngitis, pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

, skin infections
Cellulitis
Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by exogenous bacteria, and often occurs where the skin has previously been broken: cracks in the skin, cuts, blisters,...

, urinary tract infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...

s, salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

, lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...

, and chlamydia infections. It is used to prevent bacterial endocarditis in high risk people who are having dental work done, to prevent strep pneumococus infections in those without a spleen
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...

, and for both the prevention and treatment of anthrax
Anthrax
Anthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals...

. It is also a treatment for cystic acne. The UK however does not recommend its use for infectious endocarditis prophylaxis. These recommendations have not appeared to have changed the rates of infection.

Adverse effects

Side-effect
Adverse drug reaction
An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dosage. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs...

s are as those for other beta-lactam antibiotics.
Side-effects include nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

, vomiting, rashes, and antibiotic-associated colitis
Colitis
In medicine, colitis refers to an inflammation of the colon and is often used to describe an inflammation of the large intestine .Colitides may be acute and self-limited or chronic, i.e...

. Loose bowel movements (diarrhea) also may occur. Rarer, but patient-reported, 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 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.
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 who are 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
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...

 in some patients. Young children having ingested acute overdoses of amoxicillin manifested lethargy, vomiting and renal dysfunction
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...

.

Nonallergic amoxicillin rash

Somewhere between 3% and 10% of children taking amoxicillin (or ampicillin
Ampicillin
Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...

) show a late-developing (>72 hours after beginning medication and having never taken penicillin-like medication previously), often itchy 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
Measles
Measles, also known as rubeola or morbilli, is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses...

; 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, and therefore a healthcare professional is often required to distinguish between the two.

A nonallergic amoxicillin rash may also be an indicator of infectious mononucleosis
Infectious mononucleosis
Infectious mononucleosis is an infectious, widespread viral...

: Some studies indicate approximately 80-90% of patients with acute Epstein Barr virus infection treated with amoxicillin or ampicillin
Ampicillin
Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...

 develop such a rash.

Interaction

Amoxicillin may interact with the following groups of drugs:
  • Anticoagulants (e.g. warfarin, pradaxa)
  • Allopurinol (gout treatment)
  • Birth control pills
  • Certain antibiotics
  • Cancer treatment (methotrexate)
  • Uricosuric drugs
  • Typhoid vaccine

Mechanism of action

This drug acts by inhibiting the synthesis of bacterial cell wall
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

s. It inhibits cross-link
Cross-link
Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. "Polymer chains" can refer to synthetic polymers or natural polymers . When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of...

age between the linear peptidoglycan polymer chains that make up a major component of the cell wall
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

s 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).

Modes of delivery

Pharmaceutical manufacturers make amoxicillin in trihydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....

 form available as capsules, chewable and dispersible tablet
Tablet
A tablet is a pharmaceutical dosage form. It comprises a mixture of active substances and excipients, usually in powder form, pressed or compacted from a powder into a solid dose...

s plus syrup and pediatric
Pediatrics
Pediatrics or paediatrics is the branch of medicine that deals with the medical care of infants, children, and adolescents. A medical practitioner who specializes in this area is known as a pediatrician or paediatrician...

 suspension
Suspension (chemistry)
In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...

 for oral use, and as the sodium salt for intravenous administration (although the IV formulation is not available in the United States).

Amoxicillin is most commonly taken orally. The liquid forms are helpful where the patient might find it difficult to take tablets or capsules.

Research with mice (published in 2010) indicates successful delivery using intraperitoneally injected amoxicillin-bearing microparticles.

Proprietary preparations

Amoxicillin is one of the semisynthetic penicillins discovered by Beecham
Beecham (pharmaceutical company)
Beecham was a British pharmaceutical company. It was once a constituent of the FTSE 100 Index. Beecham, after having merged with SmithKline Beckman, merged with GlaxoWellcome to become GlaxoSmithKline .-History:...

 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 (with clavulanic acid
Clavulanic acid
Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...

), Amoxibiotic, Amoxicilina, Amoxidal, Apo-Amoxi, Augmentin (with clavulanic acid
Clavulanic acid
Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...

), Bactox, Betalaktam, Bioxidona, Cilamox, Clamoxyl, Curam, Dedoxil, Dispermox, Duomox, E-Mox, Enhancin, Gimalxina, Geramox, Hiconcil, Isimoxin, Klavax, Klavocin, Klavox, Lamoxy, Largopen, Moxatag, Moxilen, Moxypen, Moxyvit, Nobactam, Novamoxin, Ospamox, Panklav (with clavulanic acid
Clavulanic acid
Clavulanic acid is a competitive β-lactamase inhibitor combined with penicillin group antibiotics to overcome certain types of antibiotic resistance. It is used to overcome resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins...

),Optamox, Pamoxicillin, Panamox, Polymox, Samthongcillin, Senox, Sinacilin, Starmox, Trimox, Tolodina, Tormoxin, Wedemox, Wymox, Yucla, Zerrsox and Zimox.

External links

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