Carbapenems are antibiotics that belong to the group of beta-lactams. Originally, carbapenems were called thienamycins. Due to their broad antimicrobial spectrum of activity, they are used as drugs. Some examples are ertapenem, imipenem, doripenem, meropenem and tebipenem. Carbapenems have the status of reserve antibiotics. Within Europe, more and more resistance to carbapenems is being recorded.
What are carbapenems?
Carbapenems are antibiotics that belong to the group of beta-lactams. In principle, carbapenems are relatively well-tolerated antibiotics. Due to their spectrum of activity, they are divided into two groups. This is because they have a relatively broad spectrum of activity in both the gram-negative and gram-positive areas. In addition, the beta-lactamase they contain is characterized by high stability. The first group of carbapenems includes, for example, imipenem or cilastatin, meropenem and doripenem. It should be noted here that cilastatin alone has no antimicrobial effect. Ertapenem belongs to the second group. It differs from the other carbapenems in that it is only slightly effective against Acinetobacter and Pseudomonas. All carbapenems are ineffective against methicillin-resistant staphylococci. In principle, all carbapenems have a bactericidal effect. Since carbapenems are beta-lactam antibiotics, they are primarily used for the treatment of certain bacterial infectious diseases that are caused by sensitive pathogens. Their bactericidal effect extends to aerobic and anaerobic as well as gram-negative and gram-positive pathogens. In the majority of cases, the corresponding drugs are administered intravenously as infusions.
Pharmacologic action
The effect of carbapenems is due, on the one hand, to the special way in which they bind to penicillin-binding proteins. On the other hand, the active ingredient inhibits the cell wall synthesis of the bacteria. The excretion of carbapenems occurs via the kidneys. However, the carbapenem imipenem is a highly kidney-damaging or nephrotoxic substance. To prolong the half-life, the antibiotic is usually combined with cilastatin, which inhibits dehydropeptidase. In this way, the hydrolytic degradation of the drug is delayed in the kidney. At the same time, nephrotoxicity is reduced. Such a combination is not necessary with the other carbapenems. All carbapenems are partially metabolized and subsequently eliminated renally. The half-life in persons with healthy kidneys is approximately one hour. Due to their relatively broad spectrum, carbapenems have an enormous effect on the intestinal flora. In addition, bacteria that are resistant to carbapenems can proliferate during treatment and subsequently cause secondary infections. In terms of their chemical structure, carbapenems differ from other beta-lactams. Here, the characteristic five-membered ring of the respective beta-lactam has a carbon atom instead of a sulfur atom. Initially, the lead substance of the carbapenems was obtained from a fungal species called Streptomyces cattleya. However, this lead substance, thienamycin, is not stable in the body. For this reason, carbapenems are now produced synthetically.
Medical application and use
In principle, all carbapenems are so-called reserve antibiotics. This means that they are used only in special and difficult-to-control infectious conditions. This is because uncritical use supports the formation of resistance and increases side effects. Carbapenems are also used, for example, when resistance to other beta-lactams already exists. They are also used in the case of serious nosocomial infections caused by unknown germs, especially if the originally intended therapy is ineffective. In addition, carbapenems are also used in severe mixed infections, for example in peritonitis (inflammation of the peritoneum) with anaerobes and pyogenic pathogens. The spectrum of activity of carbapenems includes almost all pathogenic gram-negative and gram-positive bacteria with the exception of mycoplasma and chlamydia. Carbapenems are also effective against Pseudomonas aeruginosa. Carbapenems are available exclusively by parenteral route.The use of meropenem and imipenem or cilastatin is particularly useful for serious or even life-threatening infections of the kidney, urinary tract and abdomen. Serious infections of the joints and genital organs, soft tissues and skin also justify the use of the drugs. Furthermore, serious infections of the respiratory tract as well as meningitis and sepsis are also treated with the active substances. The carbapenem ertapenem is used primarily for infections of the skin and pneumonia. Inflammations of the inner lining of the heart (endocarditis) can also be treated with carbapenems. The dosage of the active ingredients is based on the specialist information. In most cases, they are administered intravenously, sometimes as an injection.
Risks and side effects
Various side effects may occur as part of the use of carbapenems. Among the most common side effects are nausea, diarrhea and vomiting, skin rashes, and other discomfort at the infusion site. Headache and inflammation of the vein also sometimes occur. Occasionally, hypersensitivity reactions have been reported. Carbapenems must not be used if hypersensitivity is already known. Also, if the patient is sensitive to other beta-lactam antibiotics, treatment with carbapenems is contraindicated. In addition, interactions may occur if carbapenems are taken concomitantly with some other agents.
