Ciprofloxacin: Mechanism Of Action And Indications

Ciprofloxacin is a drug with antibiotic properties that belongs to the fluoroquinolone family. It is a broad spectrum antibacterial drug, that is, it is effective against diseases caused by both gram + and gram- bacteria.

This characteristic differentiates it from other drugs in the quinolone family, since most are effective only against gram-bacteria.

Regarding its indications, it is usually prescribed for the treatment of moderate urinary infections, as well as the treatment of acute cystitis and lower respiratory tract infections, skin infections, and bone and joint infections.

Ciprofloxacin: broad spectrum antibiotic?

Antibiotics can be broad-spectrum or narrow-spectrum. The former are those that show their action against gram positive and gram negative bacteria, while those with a reduced spectrum are only effective against one type of bacteria.

Now, gram + and gram- bacteria are differentiated by the characteristics of their cell membranes. The former have a cell membrane composed of peptidoglycan and an internal cytoplasmic membrane formed by a double layer of lipids.

On the other hand, gram-, which, in addition to the inner cytoplasmic membrane, have another lipid bilayer in the outermost membrane. Between both membranes there is a space called the periplasmic space.

This space in gram- bacteria is formed by peptidoglycan, which is much larger and wider than in gram + bacteria. As we can see, the cell membrane of gram- is more complex than that of the opposite sign.

To know if it is one type or another, a series of tests must be carried out in the laboratory that allow us to classify the bacteria. The best known technique is the Gram stain. Next, we will see in more detail the following aspects about ciprofloxacin:

• Pharmacokinetics.
• Mechanism of action.
• Adverse reactions

Pharmacokinetics: what happens to the drug in the body?

Pharmacokinetics is a term that encompasses the absorption, distribution, metabolism and elimination processes of drugs. In this sense, it is a drug that is administered orally. It has an absorption of 70%.

However, it is important to know that ionic substances can form chelates with the drug, reducing its absorption. In addition to being administered orally, this drug can also be administered intravenously.

On the other hand, in terms of distribution, fluoroquinolones present a great diffusion, their binding to plasma proteins being minimal.

Regarding metabolism, which are the reactions that the drug undergoes in the body in order to make it more soluble in water and thus favor its elimination, it takes place in the liver. Small concentrations of four metabolites have been reported to be eliminated via the kidneys through the urine:

• Desetilenciprofloxacin.
• Sulfociprofloxacin.
• Oxociprofloxacin.
• Formilciprofloxacin.

Mechanism of action: how does it exert its effect on the body?

Ciprofloxacin owes its antibacterial action to the fact that it inhibits DNA synthesis. To do this, it binds to porins, which are proteins that are part of the membrane and allows the drug to pass into the cell.

Once inside the cell, it binds to DNA gyrase, decreasing its activity. DNA gyrase is an enzyme that reduces molecular stress by supercoiling and enables DNA replication.

In this way, by inhibiting the replication of the bacterium’s DNA, it prevents its proliferation, thus reversing the infection. In addition, human and mammalian cells contain a topoisomerase II, which at high doses can be inhibited by the drug, triggering a certain antineoplastic effect.

On the other hand, if it is administered with other drugs that inhibit protein synthesis, its action decreases, since all the structures on which it acts are protein-based.

Adverse reactions of ciprofloxacin

The most frequently reported adverse drug reactions are nausea and diarrhea. However, below we will mention a series of reactions derived from clinical trials and post-marketing surveillance with ciprofloxacin administered orally and intravenously:

• Dizziness
• Headaches
• Anorexy.
• Eosinophilia.
• Hyperactivity
• Fungal superinfections.

• Sleep and taste disorders.

Although they seem many and varied, they are very rare. It can be said, therefore, that it is a safe drug with few adverse reactions taking it at the appropriate dose.