Imipenem is an antibiotic. The active substance belongs to the group of carbapenems.
What is imipenem?
Imipenem is a broad-spectrum antibiotic because it is effective against many different types of bacteria. Imipenem is the name given to an antibiotic drug that belongs to the carbapenem subclass. Carbapenems are considered broad-spectrum antibiotics because they are effective against many different types of bacteria. They are part of the beta-lactams and usually serve as reserve antibiotics. These agents are usually used only when ordinary antibiotic preparations fail. They are also now increasingly used to combat serious hospital infections. Imipenem is produced semisynthetically from thienamycin. This natural substance is produced by the bacterium Streptomyces cattleya. Imipenem has been approved in Europe since the mid-1980s. The drug is always administered together with cilastatin.
Pharmacologic Action
Imipenem is capable of killing bacteria. The antibiotic exerts this effect by inhibiting the assembly of bacterial cell walls. Imipenem can bind to proteins responsible for docking with penicillin in both gram-negative and gram-positive bacteria. Penicillin resembles imipenem in its chemical structure. A special feature of imipenem is that it is combined with cilastatin. Cilastatin is an enzyme inhibitor. Within the kidneys, it blocks the enzyme dehydropeptidase-I (DHP-I). This participates in the removal of imipenem from the body. In this way, the duration of action of the antibiotic is increased. However, some bacterial species are insensitive to imipenem. Possible causes include weakened attachment of the antibiotic to penicillin proteins, weak permeability of the outer membrane of gram-negative bacterial species, active removal of imipenem from the cells of the bacteria, and the presence of rare enzymes by which the structure of the antibiotic is attacked. If the bacteria are resistant to other carbapenems such as doripenem, ertapenem and meropenem, there is usually also resistance to imipenem. Imipenem is largely excreted from the organism via the kidneys. Around 70 percent of the substance is excreted unchanged. The liver metabolizes the remaining 30 percent. About one percent of the antibiotic is also excreted in the stool.
Medical application and use
The combination of imipenem and cilastatin is administered to treat children and adults for complicated infections of the urinary tract, severe pneumonia that can also be acquired in the hospital, complicated infections of the abdomen or peritoneum, and severe infections of the tendons, muscles, and skin. In addition, imipenem is suitable for the treatment of infections that occur during or after childbirth. It may also be useful to administer it to treat blood poisoning (sepsis). In contrast, the use of carbapenem for meningitis is not considered effective. The spectrum of use of imipenem covers gram-negative, gram-positive and aerobic bacteria. However, it is not effective against mycoplasma, legionella, MRSA, Enterococcus faecium, Clostridium difficile and Stenotrophomonas maltophilia. Imipenem is only moderately effective against Pseudomonas. Neither imipenem nor cilastatin can be absorbed via the digestive tract. For this reason, they are always administered as an intravenous infusion prepared by healthcare professionals. The usual dose for adults and adolescents is 500 milligrams of imipenem and cilastatin given six to eight hours apart. If the patient suffers from kidney disease, the dose can be reduced.
Risks and side effects
Several side effects are conceivable from the use of imipenem and cilastatin. These primarily include nausea, vomiting, diarrhea, elevated liver enzymes, constipation or inflammation of the blood vessels, and an excess of immature blood cells. Occasionally, low blood pressure, lack of white blood cells, lack of all blood cells, muscle cramps, seizures, drowsiness, fever, and an increase in blood counts may also occur. Even mental disorders such as confusion or delusions are within the realm of possibility.The pricking of the infusion sometimes causes redness and pain at the injection site. There are also some known contraindications to taking imipenem. These include hypersensitivity to imipenem, cilastatin, or other carbapenems. Careful consideration of imipenem administration by the physician is required if the patient suffers from brain injuries or epileptic seizures. These promote seizures or confusion. The same applies if liver disease is present, as it could worsen. A study of pregnant patients taking imipenem has not been conducted. However, animal studies showed damage to the offspring. Therefore, imipenem is only used during pregnancy if the benefit to the mother outweighs the risk to her child. Imipenem is not considered suitable for children under one year of age. Interactions between imipenem and other drugs may also occur. For example, patients taking the antiviral ganciclovir at the same time sometimes suffered brain seizures. In epileptics, there is a risk of epileptic seizures breaking out if taken together with valproic acid. For this reason, physicians are always looking for an alternative for the antibiotic.
