Description

Ceftriaxone is a third-generation cephalosporin antibiotic. It is a broad-spectrum, bactericidal drug, meaning it kills a wide range of bacteria. It is administered parenterally, either through intramuscular (IM) injection or intravenous (IV) infusion. Ceftriaxone is known for its long half-life, which allows for once-daily dosing in many cases. This is a significant advantage in treatment, particularly for outpatient therapy. It is also well-known for its ability to penetrate the central nervous system (CNS), making it highly effective for treating infections of the brain and spinal cord.

Indications

Ceftriaxone is a versatile antibiotic used to treat a wide array of serious bacterial infections, including:

• Meningitis: Its ability to cross the blood-brain barrier makes it a primary choice for treating bacterial meningitis, especially those caused by Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae.

• Lower Respiratory Tract Infections: Such as community-acquired pneumonia.

• Genitourinary Infections: Including complicated urinary tract infections (UTIs) and gonorrhea. It is a standard first-line treatment for uncomplicated gonorrhea.

• Skin and Soft Tissue Infections: It is used to treat various bacterial infections of the skin and underlying tissues.

• Bone and Joint Infections: Such as osteomyelitis.

• Sepsis or Septicemia: Due to its broad-spectrum activity, it is often used as a first-line treatment for blood infections.

• Intra-abdominal Infections: Including peritonitis and other infections within the abdominal cavity.

• Surgical Prophylaxis: It is commonly administered before certain surgical procedures to prevent post-operative infections.

• Lyme disease: It is used for the treatment of disseminated Lyme borreliosis.

Mechanism of Action

Ceftriaxone is a beta-lactam antibiotic, and its mechanism of action is very similar to that of other drugs in this class, including cefotaxime and penicillins. It works by interfering with the synthesis of the bacterial cell wall, which is essential for the bacteria’s survival. The key steps are:

1. Inhibition of Penicillin-Binding Proteins (PBPs): Ceftriaxone binds to and inactivates a group of enzymes called penicillin-binding proteins (PBPs) located in the bacterial cell membrane.

2. Disruption of Peptidoglycan Cross-linking: PBPs are responsible for the transpeptidation reaction, a critical final step in the formation of the bacterial cell wall. This reaction cross-links the peptidoglycan chains, providing structural integrity and rigidity to the cell wall.

3. Osmotic Lysis: By inhibiting this cross-linking process, ceftriaxone leads to the formation of a defective, unstable cell wall. The weakened cell wall can no longer withstand the internal osmotic pressure of the bacterial cell, causing the cell to swell and burst (lyse).

4. Bactericidal Effect: This process of cell lysis directly kills the bacteria, giving ceftriaxone its bactericidal effect.

A major advantage of ceftriaxone is its stability against many beta-lactamase enzymes produced by bacteria. This allows it to be effective against many bacteria that have developed resistance to earlier-generation antibiotics.