What is the drug class of Ampicillin (Antibiotic)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: May 15, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Ampicillin is a beta-lactam antibiotic belonging to the penicillin class of antibiotics, specifically categorized as an aminopenicillin. This classification is based on its mechanism of action, which involves inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins, ultimately causing bacterial cell death 1. Ampicillin is effective against many gram-positive and some gram-negative bacteria, including strains of Streptococcus, Listeria, Enterococcus, Haemophilus influenzae, Escherichia coli, and Salmonella.

Key Characteristics of Ampicillin

  • It is typically administered orally or intravenously, with common adult dosages ranging from 250-500 mg orally every 6 hours or 1-2 g intravenously every 4-6 hours, depending on the infection being treated 1.
  • Like other penicillins, ampicillin can cause allergic reactions in susceptible individuals, and its effectiveness has been reduced over time due to the development of bacterial resistance through beta-lactamase production 1.
  • The drug's spectrum of activity and resistance patterns are crucial considerations in its clinical use, as outlined in various guidelines for the management of infections such as community-acquired pneumonia and infective endocarditis 1.

Clinical Use and Guidelines

  • Ampicillin is used in the treatment of various bacterial infections, with specific dosing recommendations provided for different patient populations, including pediatric patients 1.
  • Guidelines for the management of infective endocarditis, for example, recommend ampicillin as part of combination therapy for certain types of enterococcal infections, highlighting the importance of susceptibility testing and individualized treatment plans 1.
  • The choice of ampicillin versus other antibiotics depends on factors such as the suspected or confirmed pathogen, local resistance patterns, and patient-specific factors like allergy history and renal function 1.

From the FDA Drug Label

When ampicillin is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed Oral ampicillin-class antibiotics are poorly absorbed during labor Ampicillin is excreted in trace amounts in human milk Therefore, caution should be exercised when ampicillin-class antibiotics are administered to a nursing woman. The drug class of ampicillin is antibacterial or antibiotic, more specifically it belongs to the class of ampicillin-class antibiotics or beta-lactam antibiotics 2.

  • Main uses: treating bacterial infections
  • Key characteristics:
    • Mechanism of action: not explicitly stated in the label, but it is known that ampicillin works by inhibiting bacterial cell wall synthesis
    • Administration: available in IV form, and oral form (although oral form is poorly absorbed during labor)
    • Special considerations: use with caution in pregnant or nursing women, and patients with certain medical conditions.

From the Research

Drug Class of Ampicillin

  • Ampicillin is classified as a beta-lactam antibiotic, specifically a penicillin-type antibiotic 3, 4, 5, 6.
  • Beta-lactam antibiotics work by inhibiting the synthesis of the bacterial cell wall, ultimately leading to the death of the bacterial cell 6.
  • Ampicillin is often combined with a beta-lactamase inhibitor, such as sulbactam, to enhance its effectiveness against beta-lactamase-producing bacteria 3, 4, 5.

Mechanism of Action

  • Ampicillin, like other beta-lactam antibiotics, targets bacterial penicillin-binding proteins and disrupts peptidoglycan synthesis 6.
  • The drug covalently interacts with these proteins, inhibiting their function and ultimately leading to the death of the bacterial cell 6.

Resistance Mechanisms

  • Bacteria can develop resistance to ampicillin and other beta-lactam antibiotics through various mechanisms, including the production of serine beta-lactamase enzymes 6.
  • These enzymes can degrade beta-lactam antibiotics, rendering them ineffective against the bacterial cell 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.