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Versapen: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Versapen - General Information

Versapen is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name "penicillin" can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Versapen has in vitro activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of Versapen results from the inhibition of cell wall synthesis and is mediated through Versapen binding to penicillin binding proteins (PBPs).

 

Pharmacology of Versapen

Versapen is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name "penicillin" can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Versapen has in vitro activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of Versapen results from the inhibition of cell wall synthesis and is mediated through Versapen binding to penicillin binding proteins (PBPs).

 

Additional information about Versapen

Versapen Indication: Not Available Mechanism Of Action: Versapen is a semisynthetic penicillin prodrug which itself has no antibacterial activity, but is converted in the body to ampicillin and has actions and uses similar to those of ampicillin. Versapen is prepared by reacting ampicillin with acetone. Ampicillin rapidly decomposes because of the intramolecular attack of the side chain amino group on the lactam ring. Versapen locks up the offending amino group and prevents the decompolsition Versapen, once hydrolyzed to ampicillin (and acetone) binds to the penicillin binding proteins found in susceptible bacteria. This inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins Drug Interactions: Not Available Food Interactions: Not Available Generic Name: Hetacillin Synonyms: Not Available Drug Category: Anti-Bacterial Agents; Penicillins Drug Type: Small Molecule; Approved Other Brand Names containing Hetacillin: Hetacillin potassium; Versapen; Versapen-k; Absorption: Not Available Toxicity (Overdose): Not Available Protein Binding: Not Available Biotransformation: Hydrolyzed to active ampicillin via esterases Half Life: Not Available Dosage Forms of Versapen: Not Available Chemical IUPAC Name: (2S,5R,6R)-6-[(4R)-2,2-dimethyl-5-oxo-4-phenylimidazolidin-1-yl]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid Chemical Formula: C19H23N3O4S Hetacillin on Wikipedia: https://en.wikipedia.org/wiki/Hetacillin Organisms Affected: Enteric bacteria and other eubacteria