Ampicillin - Ampicillin capsule prescribing information
INDICATIONS AND USAGE
To reduce the development of drug-resistant bacteria and maintain the effectiveness of ampicillin capsules and other antibacterial drugs, ampicillin capsules should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. When culture and susceptibility information are available, they should be considered in selecting of modifying antimicrobial therapy, in the absence of such data, local epidemiology and susceptibility patterns contribute to the empiric selection of therapy.
Ampicillin capsules 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 . Meningitides .
Bacteriology studies to determine the causative organisms and their susceptibility to ampicillin capsules should be performed. Therapy may be instituted prior to the results of susceptibility testing.
DOSAGE AND ADMINISTRATION
Adults and pediatric patients weighing over 20 kg:
For genitourinary or gastrointestinal tract infections other than gonorrhea in men and women, the usual dose is 500 mg qid in equally spaced doses; severe or chronic infections may require larger doses. For the treatment of gonorrhea in both men and women, a single oral dose of 3.5 grams of ampicillin administered simultaneously with 1 gram of probenecid is recommended. Physicians are cautioned to use no less than the above recommended dosage for the treatment of gonorrhea. Follow-up cultures should be obtained from the original site(s) of infection 7 to 14 days after therapy. In women, it is also desirable to obtain culture test-of-cure from both the endocervical and anal canals. Prolonged intensive therapy is needed for complications such as prostatitis and epididymitis.
For respiratory tract infections , the usual dose is 250 mg qid in equally spaced doses.
Pediatric patients weighing 20 kg or less:
For genitourinary or gastrointestinal tract infections , the usual dose is 100 mg/kg/day total, qid in equally divided and spaced doses. For respiratory tract infections, the usual dose is 50 mg/kg/day total, in equally divided and spaced doses three to four times daily. Doses for children should not exceed doses recommended for adults.
All Patients, Irrespective of Age and Weight :
Larger doses may be required for severe or chronic infections. Although ampicillin is resistant to degradation by gastric acid, it should be administered at least one-half hour before or two hours after meals for maximal absorption. Except for the single dose regimen for gonorrhea referred to above, therapy should be continued for a minimum of 48 to 72 hours after the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. In infections caused by hemolytic strains of streptococci, a minimum of 10 days’ treatment is recommended to guard against the risk of rheumatic fever or glomerulonephritis (see PRECAUTIONS–Laboratory Tests ). In the treatment of chronic urinary or gastrointestinal infections, frequent bacteriologic and clinical appraisal is necessary during therapy and may be necessary for several months afterwards. Stubborn infections may require treatment for several weeks. Smaller doses than those indicated above should not be used.
CONTRAINDICATIONS
The use of ampicillin is contraindicated in individuals with a history of serious hypersensitivity reactions (e.g., anaphylaxis or Stevens-Johnson syndrome) to ampicillin or to other beta-lactam antibacterial drugs. Ampicillin is also contraindicated in infections caused by penicillinase-producing organisms.
Ampicillin is contraindicated in patients with a previous history of cholestatic jaundice/hepatic dysfunction associated with treatment with ampicillin.
ADVERSE REACTIONS
As with other penicillins, it may be expected that untoward reactions will be essentially limited to sensitivity phenomena. They are more likely to occur in individuals who have previously demonstrated hypersensitivity to penicillin and in those with a history of allergy, asthma, hay fever, or urticaria.
The following adverse reactions have been reported as associated with the use of ampicillin:
Infections and Infestations: Clostridioides difficile - associated diarrhea (see WARNINGS section).
Gastrointestinal : glossitis, stomatitis, nausea, vomiting, enterocolitis, pseudomembranous colitis, and diarrhea. These reactions are usually associated with oral dosage forms of the drugs.
Hypersensitivity Reactions : Severe cutaneous adverse reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), angioedema, and acute generalized exanthematous pustulosis (AGEP) have been reported in beta-lactam antibiotics (see WARNINGS ). An erythematous, mildly pruritic, maculopapular skin rash has been reported fairly frequently. The rash, which usually does not develop within the first week of therapy, may cover the entire body including the soles, palms, and oral mucosa. The eruption usually disappears in three to seven days. Other hypersensitivity reactions that have been reported are: skin rash, pruritus, urticaria, erythema multiforme, and an occasional case of exfoliative dermatitis. Linear IgA bullous dermatosis has been reported. Anaphylaxis is the most serious reaction experienced and has usually been associated with the parenteral dosage form.
NOTE : Urticaria, other skin rashes, and serum sickness-like reactions may be controlled by antihistamines, and, if necessary, systemic corticosteroids. Whenever such reactions occur, ampicillin should be discontinued unless, in the opinion of the physician, the condition being treated is life-threatening, and amenable only to ampicillin therapy. Serious anaphylactic reactions require emergency measures (see WARNINGS ).
Liver : Moderate elevation in serum glutamic oxaloacetic transaminase (SGOT) has been noted, but the significance of this finding is unknown.
Hemic and Lymphatic Systems : Anemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported during therapy with penicillins. These reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena.
Other adverse reactions that have been reported with the use of ampicillin are laryngeal stridor and high fever. An occasional patient may complain of sore mouth or tongue as with any oral penicillin preparation.
Drug Interactions
When administered concurrently, the following drugs may interact with ampicillin.
Allopurinol : Substantially increased incidence of skin rashes in patients receiving both drugs as compared to patients receiving ampicillin alone. It is not known whether this potentiation of ampicillin rashes is due to allopurinol or the hyperuricemia present in these patients.
Bacteriostatic Antibiotics : Chloramphenicol, erythromycins, sulfonamides, or tetracyclines may interfere with the bactericidal effect of penicillins. This has been demonstrated in vitro; however, the clinical significance of this interaction is not well-documented.
Oral Contraceptives : May be less effective and increased breakthrough bleeding may occur.
Probenecid : May decrease renal tubular secretion of ampicillin resulting in increased blood levels and/or ampicillin toxicity.
To reduce the development of drug-resistant bacteria and maintain the effectiveness of ampicillin and other antibacterial drugs, ampicillin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
DESCRIPTION
Ampicillin trihydrate is a semisynthetic penicillin derived from the basic penicillin nucleus, 6-aminopenicillanic acid. Ampicillin is designated chemically as (2S, 5 R , 6 R )-6-[( R )-2-Amino-2-phenylacetamido]-3,3- dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid. Its structural formula is:
Molecular formula: C 16 H 19 N 3 O 4 S · 3 H 2 O
Molecular weight: 403.5
Ampicillin capsules, USP for oral administration provide ampicillin trihydrate equivalent to 250 mg and 500 mg ampicillin USP. Inactive ingredients: ammonium hydroxide, black iron oxide, gelatin, magnesium stearate, potassium hydroxide, propylene glycol, shellac, sodium lauryl sulfate and titanium dioxide. Meets USP dissolution test 2.
CLINICAL PHARMACOLOGY
Ampicillin is bactericidal at low concentrations and is clinically effective not only against the gram-positive organisms usually susceptible to penicillin G but also against a variety of gram-negative organisms. It is stable in the presence of gastric acid and is well absorbed from the gastrointestinal tract. It diffuses readily into most body tissues and fluids; however, penetration into the cerebrospinal fluid and brain occurs only with meningeal inflammation. Ampicillin is excreted largely unchanged in the urine; its excretion can be delayed by concurrent administration of probenecid which inhibits the renal tubular secretion of ampicillin. In blood serum, ampicillin is the least bound of all the penicillins; an average of about 20 percent of the drug is bound to plasma proteins as compared to 60 to 90 percent of the other penicillins. The administration of 500 mg dose of ampicillin capsules results in an average peak blood serum level of approximately 3.0 mcg/mL.
Microbiology
Mechanism of Action
Ampicillin is similar to penicillin in its bactericidal action against susceptible bacteria during the stage of active multiplication. It acts through the inhibition of cell wall biosynthesis that leads to the death of the bacteria.
Mechanism of Resistance
Resistance to ampicillin is mediated primarily through enzymes called beta-lactamases that cleave the beta-lactam ring of ampicillin, rendering it inactive.
Antimicrobial Activity
Ampicillin has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections, as described in the INDICATIONS AND USAGE section.
Gram-positive Bacteria
Enterococcus spp.
Staphylococcus spp. (non-penicillinase-producing)
Streptococcus pneumoniae
Streptococcus pyogenes
Viridans group streptococci
Gram-negative Bacteria
Escherichia coli
Haemophilus influenzae (non-penicillinase-producing)
Neisseria gonorrhoeae
Neisseria meningitidis
Proteus mirabilis
Salmonella spp.
Shigella spp.
The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to 0.12 mcg/mL for ampicillin. However the efficacy of ampicillin in treating clinical infections due to these bacteria has not been established in adequate and well-controlled trials.
Gram-positive Bacteria
Bacillus anthracis
Corynebacterium xerosis
Anaerobic Bacteria
Clostridium spp.
Susceptibility Testing
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
HOW SUPPLIED
Ampicillin capsules, USP: Each capsule, for oral administration, contains ampicillin trihydrate equivalent to 250 mg or 500 mg ampicillin USP, and are supplied as:
250 mg: white opaque colored cap and body, hard gelatin capsule filled with white to off-white granular powder, imprinted with “AMP” on cap and “250” on body, with black ink.
Bottles of 100 NDC 59651-550-01 Bottles of 500 NDC 59651-550-05
500 mg: white opaque colored cap and body, hard gelatin capsule filled with white to off-white granular powder, imprinted with “AMP” on cap and “500” on body, with black ink.
Bottles of 100 NDC 59651-551-01 Bottles of 500 NDC 59651-551-05
Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].
Dispense in a tight container.
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Distributed by: Aurobindo Pharma USA, Inc. 279 Princeton-Hightstown Road East Windsor, NJ 08520 Manufactured by: Aurobindo Pharma Limited Hyderabad-500 032, India Revised: 08/2025
