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Ampicillin

  • Medical and Pharmacy Editor: John P. Cunha, DO, FACOEP
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

Brand Name: Ampi, Omnipen, Penglobe, Principen

Generic Name: Ampicillin

Drug Class: Penicillins, Amino

What Is Ampicillin and How Does It Work?

Ampicillin is a prescription penicillin-type antibiotic used to treat many different types of infections caused by bacteria, such as ear infections, bladder infections, pneumonia, gonorrhea, and E. coli or salmonella infection.

Ampicillin is available under the following different brand names: Ampi, Omnipen, Penglobe, and Principen.

Dosage of Ampicillin:

Capsules

  • 250 mg
  • 500 mg

Oral Suspension

  • 125 mg/5 ml
  • 250 mg/5 ml

Powder for injection

  • 125 mg
  • 250 mg
  • 500 mg
  • 1 g
  • 2 g
  • 10 g (adult dosing only)

Dosing Considerations

General Dosing Guidelines

Adults:

  • Orally: 250-500 mg every 6 hours
  • Intravenously/intramuscularly: 1-2 g every 4-6 hours or 50-250 mg/kg/day divided every 4-6 hours, not to exceed 12 g/day

Pediatric:

  • 400 mg/kg/day intravenously/intramuscularly divided every 6 hours
  • 50-100 mg/kg/day orally divided every 4-6 hours, not to exceed 12 g/day
  • Severe infection: 200-400 mg/kg/day intravenously/intramuscularly divided every 6 hours
  • Potential toxic dose: Children under 6 years: 300 mg/kg

Neonates under 28 days:

  • Under 7 days:
  • Infants under 2 kg: 50-100 mg/kg/day intravenously/intramuscularly divided every 12 hours
  • Infants over 2 kg: 75-150 mg/kg/day intravenously/intramuscularly divided every 8 hours
  • Infants under 1.2 kg: 50-100 mg/kg/day intravenously/intramuscularly divided every 12 hours
  • Infants 1.2-2 kg: 75-150 mg/kg/day intravenously/intramuscularly divided every 8 hours
  • Infants over 2 kg: 100-200 mg/kg/day intravenously/intramuscularly divided every 6 hours

Endocarditis Prophylaxis

Adults:

Pediatric:

  • 50 mg/kg intravenously/intramuscularly (with or without gentamicin 1.5 mg/kg for gastrointestinal/genitourinary) within 30-60 minutes before procedure
  • Dosing considerations:
    • American Heart Association guidelines recommended only for high-risk patients

Endocarditis

  • 12 g/day continuous intravenous infusion or divided every 4 hours

Genitourinary Tract Infections (excluding Gonorrhea)

Adults:

  • 1-2 g intravenously every 6 hours with gentamicin if enterococcus suspected

Pediatric:

  • Children under 40 kg: 50-100 mg/kg/day intravenously/intramuscularly divided every 6 hours
  • Children over 40 kg: 500 mg intravenously/intramuscularly divided every 6 hours

Gastrointestinal Tract Infections

Adults:

  • 500 mg intravenously every 6 hours; larger doses may be necessary in severe or chronic infection

Pediatric:

  • Children under 20 kg: 50-100 mg/kg/day orally divided every 6 hours
  • Children over 20 kg: 500 mg orally every 6 hours
  • Children under 40 kg: 50 mg/kg/day intravenously/intramuscularly divided every 6-8 hours
  • Children over 40 kg: 500 mg intravenously/intramuscularly every 6 hours

Gonorrhea

Adults:

  • 3.5 g intravenously administered once simultaneously with 1 g of probenecid

Pediatric:

  • Children under 20 kg: safety and efficacy not established
  • Children over 20 kg: 3.5 g orally administered once simultaneously with 1 g of probenecid

Respiratory Tract Infections

Adults:

  • 250 mg intravenously every 6 hours

Pediatric:

  • Children under 20 kg: 50 mg/kg/day orally divided every 6-8 hours
  • Children over 20 kg: 250 mg orally every 6 hours
  • Children under 40 kg: 25-50 mg/kg/day intravenously/intramuscularly divided every 6-8 hours
  • Children over 40 kg: 250-500 mg intravenously/intramuscularly every 6 hours

Bacterial Meningitis

  • 150-200 mg/kg/day intravenously every 6-8 hours

Group B Streptococcus

Neonatal prophylaxis

  • 2 g intravenously initially, followed by every 4 hour until delivery

Listeria Infection

  • 2 g intravenously every 4 hours

Cholera

Pediatric:

  • 50 mg/kg/day orally divided every 6 hours for 3 days; not to exceed 2 g/day

Administration

  • Take oral dosage form on an empty stomach

Dosing Modifications

Renal Impairment

  • Creatinine Clearance less than 10 ml/min: administer every 12-24 hours
  • Creatinine Clearance 10-50 ml/min: administer every 6-12 hours
  • Creatinine Clearance over 50 ml/min: administer every 6 hours

Hepatic Impairment

  • Not studied

What Are Side Effects Associated with Using Ampicillin?

Common Side effects of Ampicillin include:

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Ampicillin?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Ampicillin has no known severe interactions with other drugs.

Serious Interactions of ampicillin include:

Ampicillin has moderate interactions with at least 29 different drugs.

Mild interactions of ampicillin include:

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns or for more information about this medicine.

What Are Warnings and Precautions for Ampicillin?

Warnings

  • This medication contains ampicillin. Do not take Ampi, Omnipen, Penglobe, or Principen if you are allergic to ampicillin or any ingredients contained in this drug
  • Keep out of reach of children
  • In case of overdose, get medical help or contact a Poison Control Center immediately

Contraindications

Effects of Drug Abuse

  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Ampicillin?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Ampicillin?"

Cautions

  • Allergy to cephalosporins and/or carbapenems
  • Adjust dose in renal failure; evaluate rash and differentiate from hypersensitivity reaction
  • Endocarditis prophylaxis: Use only for high-risk patients, per American Heart Association Guidelines
  • Prolonged use associated with fungal or bacterial superinfection

Pregnancy and Lactation

  • Use of ampicillin may be acceptable during pregnancy
  • Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies were done and showed no risk
  • Ampicillin is excreted in breast milk; use with caution while breastfeeding
Reviewed on 6/7/2017

Medscape. Ampicillin.
https://reference.medscape.com/drug/ampi-omnipen-ampicillin-342475#0
RxList. Principen.
https://www.rxlist.com/principen-drug.htm

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