CLINICAL PHARMACOLOGY
Ampicillin for Injection, USP diffuses readily into most body tissues and fluids. However, penetration into the cerebrospinal fluid and brain occurs only when the meninges are inflamed. Ampicillin is excreted largely unchanged in the urine and its excretion can be delayed by concurrent administration of probenecid. The active form appears in the bile in higher concentrations than those found in serum. Ampicillin is the least serum-bound of all the penicillins, averaging about 20% compared to approximately 60 to 90% for other penicillins. Ampicillin for Injection, USP is well tolerated by most patients and has been given in doses of 2 grams daily for many weeks without adverse reactions.
Microbiology
While in vitro studies have demonstrated the susceptibility of most strains of the following organisms, clinical efficacy for infections other than those included in the
INDICATIONS AND USAGE
section has not been demonstrated.
The following bacteria have been shown in in vitro studies to be susceptible to Ampicillin for Injection, USP:
GRAM-POSITIVE ORGANISMS: Hemolytic and nonhemolytic streptococci, D.
pneumoniae
, nonpenicillinase-producing staphylococci, Clostridia spp., B.
anthracis
, Listeria
monocytogenes
, and most strains of enterococci.
GRAM-NEGATIVE ORGANISMS: H.
influenzae
, N.
gonorrhoeae
, N.
meningitidis
, Proteus mirabilis, and many strains of Salmonella, Shigella, and E. coli.
AMPICILLIN does not resist destruction by penicillinase.
Susceptibility Tests
Ampicillin Susceptibility Test Discs, 10 mcg, should be used to estimate the in vitro susceptibility of bacteria to Ampicillin for Injection, USP.
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