- Piperacillin is a broad-spectrum ureidopenicillin antibiotic with a molecular formula of C23H27N5O7S and a molecular mass of 517.56 g/mol. Its structure features a beta-lactam ring fused to a thiazolidine ring, characteristic of penicillins, with an additional ureido group and a piperazine side chain. These modifications enhance its activity against gram-negative bacteria, particularly Pseudomonas aeruginosa, and classify it as a member of the ureidopenicillin subclass.
- The antibiotic exerts its bactericidal action by inhibiting bacterial cell wall synthesis. It specifically binds to penicillin-binding proteins (PBPs), enzymes involved in the cross-linking of peptidoglycan chains. This inhibition disrupts cell wall integrity, leading to osmotic instability and bacterial cell lysis. Piperacillin’s extended spectrum of activity is attributed to its ability to penetrate the outer membrane of gram-negative bacteria more effectively than earlier penicillins.
- Piperacillin demonstrates broad-spectrum activity against a wide range of gram-positive and gram-negative bacteria, including Enterobacteriaceae (e.g., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis), Pseudomonas aeruginosa, and anaerobic organisms such as Bacteroides fragilis. It is also effective against many Streptococcus and Enterococcus species, though its activity against methicillin-resistant Staphylococcus aureus (MRSA) is limited. Piperacillin is often combined with a beta-lactamase inhibitor, such as tazobactam, to enhance its stability against beta-lactamase-producing organisms.
- The pharmacokinetic profile of piperacillin includes rapid distribution following intravenous administration, achieving therapeutic concentrations in most tissues and body fluids, including the lungs, kidneys, and bile. It is minimally protein-bound and primarily excreted unchanged in the urine, with a half-life of approximately 1 hour in patients with normal renal function. Dosage adjustments are required in patients with impaired kidney function to avoid accumulation and toxicity.
- Despite its efficacy, piperacillin is associated with potential adverse effects, including hypersensitivity reactions (e.g., rash, anaphylaxis), gastrointestinal disturbances (e.g., nausea, diarrhea), and, rarely, neutropenia or electrolyte imbalances. Its use is generally well-tolerated, but careful monitoring is required in patients with a history of penicillin allergy.
