From the Guidelines
Ampicillin should be used in the treatment of bacterial infections, particularly those caused by gram-positive organisms and some gram-negative bacteria, with a typical dose of 150 mg/kg per day divided every 8 hours for infants 8-21 days old, as recommended by the most recent guidelines 1.
Indications for Use
Ampicillin is commonly prescribed for:
- Urinary tract infections (UTIs)
- Bacterial meningitis
- Gastrointestinal infections
- Respiratory tract infections
- As prophylaxis before certain surgeries ### Similar Drugs Similar drugs in the penicillin class include:
- Amoxicillin (often preferred for oral use due to better absorption)
- Penicillin V
- Dicloxacillin
- Nafcillin
- Extended-spectrum penicillins like piperacillin and ticarcillin offer broader coverage against gram-negative bacteria ### Mechanism of Action Ampicillin works by inhibiting bacterial cell wall synthesis, causing cell death.
Important Considerations
Important considerations include:
- Checking for penicillin allergies before use, as cross-reactivity is common within this class
- Being aware that ampicillin can reduce the effectiveness of oral contraceptives
- Potential interactions with certain medications like allopurinol and methotrexate ### Dosage and Administration The dosage and administration of ampicillin vary depending on the infection type and patient age, with the most recent guidelines recommending:
- 150 mg/kg per day divided every 8 hours for infants 8-21 days old 1
- 50 mg/kg per dose every 24 hours for infants 22-28 days old 1
- 50 mg/kg per dose every 24 hours for infants 29-60 days old 1
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of Ampicillin capsules, Ampicillin for Oral Suspension and other antibacterial drugs, Ampicillin capsules and Ampicillin for Oral Suspension should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria Ampicillin capsules and Ampicillin for oral suspension are indicated in the treatment of infections caused by susceptible strains of the designated organisms listed below: Infections of the genitourinary tract including gonorrhea - E. coli, P. mirabilis, enterococci, Shigella, S. typhosa and other Salmonella and nonpenicillinase-producing N. gonorrhoeae Infections of the respiratory tract - Nonpenicillinase-producing H. influenzae and staphylococci, and streptococci including Streptococcus pneumoniae. Infections of the gastrointestinal tract -Shigella, S. typhosa and other Salmonella, E. coli, P. mirabilis, and enterococci. Meningitis - N Meningitidis
Ampicillin should be used to treat infections caused by susceptible bacteria, including:
- Genitourinary tract infections such as gonorrhea, caused by E. coli, P. mirabilis, enterococci, Shigella, S. typhosa, and other Salmonella
- Respiratory tract infections caused by nonpenicillinase-producing H. influenzae, staphylococci, and streptococci, including Streptococcus pneumoniae
- Gastrointestinal tract infections caused by Shigella, S. typhosa, and other Salmonella, E. coli, P. mirabilis, and enterococci
- Meningitis caused by N. meningitidis Drugs that are like ampicillin include other beta-lactam antibiotics 2
From the Research
When to Use Ampicillin
Ampicillin is used to treat various infections, including:
- Upper airway infections such as otitis media, bronchitis, and pneumonia 3
- Urinary tract infections caused by Escherichia coli, Proteus mirabilis, and enterococci 3
- Gonorrhoea 3
- Hemophilus meningitis 3
- Typhoid fever 3
Drugs Similar to Ampicillin
Some drugs similar to ampicillin include:
- Amoxicillin, which has been shown to have in vitro activity equal to ampicillin and produces higher blood levels for a longer period of time 3
- Pivampicillin, which offers an advantage over ampicillin with twice the blood levels of a comparable dose 3
- Epicillin, which has no superiority to ampicillin 3
- Cyclacillin, which has initially high blood levels but is less active and rapidly cleared from the body 3
- Amoxicillin-sulbactam, which has broad-spectrum antibacterial activity against most common pathogens of the respiratory and urinary tracts 4
- Ampicillin-sulbactam, which is effective against Gram-positive and Gram-negative aerobic and anaerobic bacteria, but not against Pseudomonas aeruginosa and pathogens producing extended-spectrum beta-lactamases 5
- Sultamicillin, which is a mutual prodrug of ampicillin and sulbactam, and is effective in the treatment of upper and lower respiratory tract infections 6, 7
Indications for Use
These drugs are indicated for use in various infections, including: