Azlocillin

Pharmacological group and classification

Azlocillin (Azlocillin) belongs to the broad group of beta-lactam antibiotics. Within this group, it represents the class of broad-spectrum semisynthetic penicillins, specifically the ureidopenicillin subgroup.

Its closest subgroup "relatives" are piperacillin and mezlocillin. Historically and pharmacologically, ureidopenicillins are compared with another subgroup — carboxypenicillins (carbenicillin, carfecillin, ticarcillin), as both groups were developed to combat severe Gram-negative infections.

Spectrum of antimicrobial activity

The baseline spectrum of activity of azlocillin is similar to that of carboxypenicillins, but the drug has two critically important advantages:

1. Expanded activity: Azlocillin demonstrates higher activity against bacteria of the genus Klebsiella and also more effectively suppresses Gram-positive flora.
2. Antipseudomonal potency: This is the main indication for the drug. Against Pseudomonas aeruginosa, azlocillin is 4–8 times more active than carboxypenicillins.

Comparative activity against Pseudomonas aeruginosa

If we rank semisynthetic penicillins in descending order of their efficacy against Pseudomonas infection (from most potent to least active), the picture looks as follows:

• 1st place (highest activity): Azlocillin and Piperacillin.
• 2nd place (moderate activity): Mezlocillin and Ticarcillin.
• 3rd place (lowest activity in the series): Carbenicillin.

Resistance issue

Despite its high antibacterial activity, azlocillin has a significant vulnerability. The drug is destroyed by $\beta$-lactamases — specific enzymes produced by staphylococci and many Gram-negative bacteria.

This means that in infections caused by $\beta$-lactamase-producing strains, azlocillin monotherapy will be ineffective: bacteria will simply cleave the beta-lactam ring of the antibiotic before it can take effect.

Dosage forms and administration rules

Azlocillin is not absorbed in the gastrointestinal tract, so it is used exclusively parenterally. The drug is available as a powder in vials, from which a solution is prepared ex tempore (immediately before use).

Vial dosages depend on the route of administration:

• For intramuscular (I.M.) administration: 0.5 g, 1.0 g, and 2.0 g vials.
• For intravenous (I.V.) administration: larger volume vials — 4.0 g, 5.0 g, and 10.0 g.

Standard dosing regimen: The drug is administered intramuscularly or intravenously (bolus or infusion). For this purpose, a 10% aqueous solution is prepared. The standard dosage is 2.0 g 4 times a day.

Sample prescription

Let's write a prescription for azlocillin for intramuscular administration according to the standard regimen (2.0 g 4 times a day) for 5 days. One day will require four 2.0 g vials, and the full course requires 20 vials.

```latin Rp.: Azlocillini 2.0 D.t.d. N. 20 S. Intramuscularly. Dissolve the contents of the vial in water for injections (to obtain a 10% solution), administer 2.0 g 4 times a day. ```

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanism of action of beta-lactam antibiotics on the bacterial cell wall.
• Carboxypenicillins: carbenicillin, carfecillin, ticarcillin.
• Other ureidopenicillins: piperacillin and mezlocillin.
• Mechanisms of β-lactamase production by Gram-negative bacteria and staphylococci.
• Principles of treatment for Pseudomonas infections.

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