Amoxicillin is a medication commonly used, either alone or in combination with clavulanic acid, to treat different bacterial infections. It is especially effective against infections of the upper and lower respiratory tract, as well as infections affecting the middle ear and paranasal sinuses. Amoxicillin is also used for infections of the urinary tract, genital system, including gonorrhea, skin and soft tissue infections, intra-cavity infections, abdominal disease, Lyme disease, sepsis, oral infections in dentistry, and for the prevention of endocarditis. When included in combination therapy with other drugs, amoxicillin is effective in eradicating Helicobacter pylori in patients with peptic ulcer disease.
Amoxicillin Action
Amoxicillin is a medication with bactericidal properties. Its mechanism of action is based on inhibiting the synthesis of the bacterial cell wall, which prevents the development and multiplication of bacteria.
It shows antibacterial activity against strains such as:
- Streptococcus spp., including S. pneumoniae, also moderately susceptible strains if the infection is related to the respiratory system;
- Enterococcus spp., while strains of E. faecium are often resistant;
- S. aureus and S. epidermidis, only penicillinase-negative strains, since approx. 90% of strains produce penicillinase;
- Listeria monocytogenes;
- E. coli, with the percentage of resistant strains being about 40-60%;
- Shigella, although resistant strains are present and ampicillin shows better activity;
- H. pylori, with single resistant strains.
Uses
The indications for the administration of amoxicillin are:
- upper respiratory tract infections,
- lower respiratory tract infections,
- inflammation of the genitourinary tract,
- skin and soft tissue infections,
- gastrointestinal infections.
In addition, amoxicillin may be administered for the treatment of oral cavity infections and as part of dental prophylaxis after oral surgery.
Drug Mechanism
Amoxicillin is an antibiotic, a semi-synthetic penicillin, with a structure similar to ampicillin. Penicillins belong to β-lactam antibiotics. These antibiotics work by blocking one of the final stages in the biosynthesis of the bacterial cell wall, the so-called transpeptidation. This is the process of cross-linking the primary linear structure, which allows the bacterial cell wall to obtain a stable form. This effect is possible because the antibiotic has a structure similar to the natural substances used by bacteria to build the cell wall. Inhibition of the transpeptidase enzyme involved in this process leads to inhibition of cell wall construction and then to the breakdown of the bacterial cell. Due to this mechanism of action, β-lactam antibiotics show their strongest activity during the phase of the highest bacterial development and most intensive growth. Amoxicillin has a broad spectrum of antibacterial activity, meaning it is active against many different species of bacteria. It is a bactericidal antibiotic, so it kills the bacterial cell.
For an antibiotic to work effectively in treating an infection, it must reach a concentration at the infection site that is high enough to inhibit the growth of the pathogenic microorganism or kill it, while still remaining safe for human cells. When both of these conditions are fulfilled, the microorganism is considered antibiotic sensitive. If the antibiotic fails to meet either condition, it is considered ineffective, and the microorganism is described as antibiotic resistant. Antibiotic resistance may be innate or acquired as a result of genetic mutation in bacteria and selection of resistant strains, or through transfer of resistance genes between bacterial cells, which is called horizontal transfer. One important mechanism of bacterial resistance to β-lactam antibiotics is degradation and inactivation of the antibiotic by enzymes called β-lactamases. This phenomenon can be prevented by administering substances that inhibit these enzymes together with the antibiotic. These substances are called β-lactamase inhibitors. They include, among others, clavulanic acid and sulbactam. These substances permanently attach to the structures of the enzyme that breaks down the antibiotic and inactivate it, allowing the antibiotic to work. Amoxicillin is a penicillin sensitive to beta-lactamases, therefore preparations containing amoxicillin and clavulanic acid are also used in the treatment of infections.
The bactericidal activity of β-lactam antibiotics depends on how long the concentration of the drug at the infection site remains sufficiently high.
Taking instructions
After oral administration, amoxicillin is absorbed very well and quickly from the gastrointestinal tract, regardless of the meal and the type of diet. It is resistant to gastric juice. The biological half-life is approximately 1 hour; in renal failure, it is extended to 12–16 hours. Most of the dose is excreted through the kidneys within 6 hours, mostly unchanged.
Effects
The effect of Amoxicillin lasts for 6-8 hours after administration, and 80-95% is absorbed from the gastrointestinal tract, regardless of the meal and the type of diet. It is resistant to gastric juice.
It penetrates well into urine, bile, synovial, pleural, pericardial, and peritoneal fluid, bronchial secretions, amniotic fluid, and the middle ear. Approximately 60% of the dose is excreted through the kidneys within 6-8 hours, mostly unchanged.
Contraindications to use
To protect your safety and well-being, it is important to read the leaflet included with your medication carefully before use. This leaflet contains important information, including indications, contraindications, dosage, and possible side effects. If you have any questions or concerns, consult your doctor or pharmacist before using the medication. Improper use of any medication can pose a serious threat to your health or even your life.
Amoxicillin is an antibiotic that should not be used in case of hypersensitivity to the active substance or any component of the preparation. In addition, it is not recommended to administer the drug to patients with suspected infectious mononucleosis.
A careful inquiry should be made about previous allergic reactions to penicillin antibiotics. Caution should be exercised in patients with impaired renal function. In people with reduced urine volume, crystalluria may occur. The drug may be used during pregnancy if the benefits of treatment outweigh the risks.
Drug interactions
Amoxicillin may interact with other medications.
It is not recommended to use the preparation in parallel with:
- probenecid,
- anticoagulants,
- allopurinol,
- warfarin,
- methotrexate.
In addition, amoxicillin has an antagonistic effect, e.g. with tetracyclines, macrolides, and sulfonamides. However, it works synergistically with aminoglycosides.
Side effects
Taking medications that contain amoxicillin may cause side effects. Common side effects include skin rash, nausea, and diarrhea. Hives, itching, and vomiting are uncommon. Mucosal and skin candidiasis, transient thrombocytopenia, and haemolytic anemia develop very rarely. Severe allergic reactions are possible.
Some patients may experience allergic reactions after using beta-lactam antibiotics. These reactions may appear as skin reactions, such as rash, itching, or hives, and less often as severe changes, such as swelling, blistering, or exfoliative dermatitis. Allergic reactions can sometimes spread throughout the body and even lead to life-threatening anaphylactic shock. Serious allergic reactions occur more often after intravenous administration than after oral administration. If you experience an allergic reaction after taking an antibiotic, seek medical advice quickly, as you may need to stop the antibiotic, switch to another one, and receive additional treatment for the allergy. An allergy to one of the penicillins is associated with an increased risk of an allergic reaction to another β-lactam drug. Importantly, hypersensitivity reactions may appear both during the first administration of the antibiotic and during later administrations.
Other side effects that may occur after using β-lactam antibiotics are gastrointestinal complaints, including nausea, loss of appetite, vomiting, flatulence, loose stools, diarrhea, and taste disturbances. They are usually mild and often disappear during or after treatment. In general, these side effects can be reduced by taking amoxicillin with meals. It may also be helpful to take preparations that restore the normal composition of the intestinal flora.
Disclaimer
This information is provided for educational purposes only and is not medical advice. Do not use it to purchase, start, stop, or change treatment without consulting a qualified healthcare professional. Product names, trademarks, companies, and referenced materials are mentioned only for informational and legal purposes.