Ampicillin introduced in 1961 has been administered in the treatment of diverse
infections by both oral and parenteral means. Oral
infections of the upper airways such as
otitis media,
bronchitis, and
pneumonia have responded with high success rates since the microorganisms involved have remained sensitive to
ampicillin. Similarly, out-patient
urinary tract infections caused by Escherichia coli, Proteus mirabilis, and enterococci are cured.
Typhoid fever may yet be treated with
ampicillin, but
shigellosis has become refractory with the development of resistant strains.
Ampicillin has assumed a prominent role in the treatment of gonorrhoea. Parenteral
ampicillin is still a mainstay of the treatment of
Hemophilus meningitis, but the recent appearance of
ampicillin resistant strains may become a serious problem. A number of derivatives and analogues of
ampicillin have been developed. Among the compounds,
hetacillin,
metampicillin and
pivampicillin which hydrolyze in the body to yield
ampicillin, only
pivampicillin appears to offer advantage over the parent compound. Blood levels are twice those of a comparable dose of
ampicillin. However, more comparisons with
ampicillin in clinical situations are needed. The other analogues of
ampicillin are
epicillin,
cyclacillin and
amoxicillin.
Epicillin has no superiority to
ampicillin, and the
cyclacillin data do not show clear superiority over
ampicillin in spite of initially high blood levels, since the compound is less active and so rapidly cleared from the body.
Amoxicillin, on the other hand, has been shown to have it vitro activity equal to
ampicillin and to produce higher blood levels for a longer period of time. Clinical studies have substantiated efficacy in treatment of
otitis media,
pharyngitis,
bronchitis,
pneumonitis, and
urinary tract infections at doses half those of
ampicillin. It has been effective in gonorrhoea and
typhoid, but not in
shigellosis. It would seem that to date only
pivampicillin and
amoxicillin, particularly the later, should be considered as replacements of
ampicillin in oral
therapy.