Australian Online Pharmacy

Classification of Antibiotics

The main pharmacodynamic characteristics of each antimicrobial drug are the spectrum and degree of its activity against a particular type of microorganisms. Quantitative expression of the activity of the drug is its minimum inhibitory concentration (MPC) for a particular pathogen, while the smaller it is, the greater the activity against this pathogen has the drug. It is very significant that in recent years, the interpretation of the pharmacodynamics of antimicrobial drugs has expanded to include the relationship between the concentrations of the drug in the body or in an artificial model and its activity.

Based on this, there are two groups of antibiotics:

Antibiotics with "concentration-dependent" antimicrobial activity (examples — aminoglycosides, fluoroquinolones, lipopeptides) is characterized by the fact that the degree of bacterial death correlates with the concentration of the antibiotic in the biological environment, in particular in serum. Therefore, the purpose of the dosing regimen of antibiotics with such action is considered to achieve the maximum tolerated concentration of the drug.

Antibiotics with "time-dependent" activity (penicillins), cephalosporins, carbapenems, vancomycin) the most important condition is long-term maintenance of concentration at a relatively low level (3-4 times higher than MPC). Moreover, with increasing drug concentration, the effectiveness of therapy does not increase. The purpose of dosing regimens of such drugs is to maintain the concentration of an antibiotic in the serum and the focus of infection, 4 times higher than the MPC for a certain pathogen, for 40-60 time interval between doses.

Origin and impact

Antibiotics of microbial, plant or animal origin, inhibiting the growth or causing the death of some microorganisms, are most often the product of actinomycetes. In this case, the suffix "mycin"is present in the name of the active substance.

In other cases, antibiotics are produced by non-bacterial bacteria. As medicines they are used because at total impact on the simplest cells they do not affect the functions of the whole body or cause minor damage.

Often such drugs are prescribed during the treatment of cancer as antitumor (cytostatic) drugs.

Usually these funds do not treat viral diseases such as influenza, chickenpox, measles, rubella, hepatitis and others, but a separate number of tetracyclines acts on them comprehensively.

What is the antibiotic

This is a group of drugs that have the ability to block the synthesis of proteins and thereby inhibit the reproduction, growth of living cells.

All types of antibiotics are used to treat infectious processes that are caused by different strains of bacteria: Staphylococcus, Streptococcus, meningococcus. The drug was first developed in 1928 by Alexander Fleming.

Assign antibiotics of some groups in the treatment of cancer pathology in the combined chemotherapy. In modern terminology, this type of drug is often called antibacterial drugs.

Classification of antibiotics by mechanism of action

The first drugs of this type were medicines based on penicillin. There is a classification of antibiotics into groups and mechanism of action.

Some of the drugs have a narrow focus, others – a wide range of actions. This parameter determines how much the drug will affect human health (both in positive and negative terms).

Medications help to cope or reduce the mortality rate of such serious diseases:

  • sepsis;
  • gangrene;
  • meningitis;
  • pneumonia;
  • syphilis.


The action of this group of drugs is aimed at inhibiting the synthesis of proteins by the cells of microorganisms, which prevents them from further multiplying and developing. The result of the action of the drug is to limit the further development of the pathological process. This effect is typical for the following groups of antibiotics:

  • lincosamines;
  • macrolides;
  • aminoglycosides.

Classification of antibiotics according to chemical composition

The main division of drugs is carried out according to the chemical structure. Each of them is based on a different active substance.

This separation helps to fight purposefully with a certain type of microbes or provide a wide range of action on a large number of varieties.

This does not allow the bacteria to develop resistance (resistance, immunity) to a particular type of drug. The main types of antibiotics are described below.


This is the very first group that was created by man. Antibiotics penicillin group (penicillium) has a wide range of effects on microorganisms. Within the group there is an additional division into:

  • natural penicillin - produced by fungi under normal conditions (phenoxymethylpenicillin, benzylpenicillin);
  • semi-synthetic penicillins, have greater resistance against penicillinases, which significantly expands the range of action of the antibiotic (methicillin, oxacillin drugs);
  • extended action – drugs ampicillin, amoxicillin;
  • drugs with a broad spectrum of action – drug of azlocillin, mezlocillin.

In order to reduce the resistance of bacteria to this type of antibiotics, penicillinase inhibitors are added: sulbactam, tazobactam, clavulanic acid. Obvious examples of such medicines are: Tazocin, Augmentin, Disrobed. Assign funds for the following pathologies:

  • respiratory infections: pneumonia, sinusitis, bronchitis, laryngitis, pharyngitis;
  • genitourinary: urethritis, cystitis, gonorrhea, prostatitis;
  • digestive: dysentery, cholecystitis;
  • syphilis.
  • Cephalosporins

    Bactericidal property of this group has a wide spectrum of action. There are the following generation relatosporno:

    • I-e, drugs cephradine, cephalexin, Cefazolin;
    • II-e, funds with cefaclor, cefuroxime, cefoxitin, cefotiam;
    • III-e, medication ceftazidime, Cefotaxime,and cefoperazone, Ceftriaxone, cefodizime;
    • IV-e funds cefpirome, cefepime;
    • V-e, medicine Floridiana, ceftaroline, petrosana.

    There is a large part of the antibacterial drugs of this group only in the form of injections, so they are used more often in clinics. Cephalosporins are the most popular type of antibiotics in hospital treatment. Assign this class of antibacterial agents when:

    • pyelonephritis;
    • the generalization of an infection;
    • inflammation of soft tissues, bones;
    • meningitis;
    • pneumonias;
    • lymphangitis.


    This group of antibacterial drugs have as a base a macrocyclic lactone ring.

    Macrolide antibiotics have bacteriostatic divite against gram-positive bacteria, membrane and intracellular parasites. Macrolides in the tissues are much more than in the blood plasma of patients.

    Means of this type have low toxicity, if necessary, they can be given to a child, a pregnant girl. Microlitic divided into the following types:

    • Natural. Was first synthesized in the 60-ies of XX century, these are means spiramycin, erythromycin, midecamycin, josamycin.
    • A prodrug, the active form was adopted after metabolism, for example, troleandomycin.
    • Semi-synthetic. This means clarithromycin, telithromycin, azithromycin, dirithromycin.


    Active use of this series of drugs is carried out in the treatment of infections that caused gram-negative flora. Antibiotics have a bactericidal effect.

    The drugs show high efficiency, which is not associated with an indicator of the activity of the patient's immunity, making these drugs indispensable for its weakening and neutropenia.

    There are the following generations of these antibacterial agents:

    • Preparations kanamycin, neomycin, levomycetin, streptomycin belong to the first generation.
    • The second includes funds with gentamicin, tobramycin.
    • The third includes drugs amikacin.
    • The fourth generation is represented by isepamicin.


    One of the largest groups of antibacterial agents, have a wide bactericidal effect on pathogens. All medicines – Hiking nalidixic acid. Active use of fluoroquinolones began in the 7th year, there is a classification by generations:

    • medicines of oxolinic, nalidixic acid;
    • products with ciprofloxacin, ofloxacin, pefloxacin, norfloxacin;
    • drugs levofloxacin;
    • drugs with moxifloxacin, Gatifloxacin, hemifloxacin.

    The latter type is called "respiratory", which is associated with the activity against microflora, acting as a rule, the cause of pneumonia. Use medicines of this group for therapy:

    • bronchitis';
    • sinusites';
    • gonorrheas;
    • intestinal infection;
    • tuberculosis';
    • sepsis';
    • meningitis's;
    • prostatitis's.