320 Section 9/ Chemotherapygram negative organisms. They are
hydrolysed by penicillinase.
AMPICILLIN
It is a broad spectrum penicillin which
is not destroyed by gastric acid but is
penicillinase susceptible. It is more effective
than benzyl penicillin against a variety of
gram negative microorganisms.
After oral administration it is readily but
incompletely absorbed and food interferes
with its absorption. Peak plasma level are
reached within two hours after oral
administration and one hour after IM
administration. It is excreted in urine in
unchanged form and high amount is also
present in the bile.
Adverse effects include skin rash,
nausea, epigastric distress, diarrhoea, drug
fever, urticaria etc.
It is used in infection caused by
susceptible gram positive and gram
negative organisms (respiratory tract, soft
tissue, gonococcal, GI and genitourinary
infections), septicaemia, meningitis, chronic
bronchitis, otitis media, sinusitis, invasive
salmonellosis and cholecystitis.
AMOXYCILLIN
Amoxycillin is a semisynthetic
penicillin, a close congener of ampicillin and
active against gram positive and negative
organisms. Its absorption is more complete
than ampicillin. Food does not interfere with
its absorption. Its absorption after oral
administration is complete hence less
incidence of diarrhoea. It is eliminated in
urine in unchanged form.
Adverse effects include nausea,
epigastric distress, diarrhoea, skin rash,
urticaria, serum sickness, thrombocytopenia,
leucopenia, eosinophilia etc.
It is used in respiratory, genitourinary,
skin and soft tissue, ENT infections caused
by pneumococci, streptococci, staphylo-
cocci, H. influenzae, E. coli and other suscep-
tible organisms. Also useful in Chlamydia
trachomatis in pregnancy, meningitis due to
susceptible strains of gram negative micro-
organisms, enteric fever, gonococcal urethri-
tis, bacteriaemia and septicaemia.
Amoxycillin is also used in chemoprophy-
laxis during dental procedures.
Amoxycillin is also used in combina-
tion with clavulanate potassium. The for-
mulation of amoxycillin with clavulanic acid
protects amoxycillin from degradation by
beta lactamase enzymes and effectively ex-
tends the antibiotic spectrum of amoxycillin
to include β lactamase producing bacteria
normally resistant to amoxycillin and other
betalactam antibiotics.
Amoxycillin along with bromhexine
and carbocisteine is used in bronchitis,
bronchopneumonia, bronchiectasis,
sinusitis and otitis media.
Amoxycillin along with cloxacillin is
used in lower respiratory tract, skin and soft
tissue, urinary tract and postoperative
infections, osteomyelitis, gynaecological
infections, septicaemia, bacterial endocarditis
and bacterial meningitis.
Amoxycillin along with probenecid is
used in bacterial septicaemia, skin and soft
tissue infection, acute and chronic
respiratory tract infections.