Penicillins
ADDITIONAL DATA
discovered by Alexander Fleming
from Penicillum molds
more bacterial species have synthesized the enzyme penicillinase
nafcillin
oxacillin
treatment of
1. streptococcal infections
a. pharyngitis
b. tonsillitis
c. scarlet fever
d. endocarditis
e. pneumococcal infections
f. rat-bite fever
g. diptheria
h. anthrax
i. syphilis
j. gonococcal infections
k. meningococcal meningitis
needs to be taken for 7 to 10 days
ADVERSE EFFECTS
1. nausea
2. diarrhea
3. rash
4. superinfections
Penicillins
1
5. glossitis
6. stomatitis
7. gastritis
8. sore mouth
9. furry tongue
PHARMACOKINETICS
absorbed from the GI tract
peak levels in 1 hour
sensitive to gastric acid levels
enters breast milk
C/Is and CAUTIONS
allergies- (Penicillin sensitivity test are available)
use on pregnant woman should be limited
perform Culture and Sensitivity test
Effective against
gram-positive organism
gram-negative cocci
non-beta lactamase producing anaerobes
little activity against
gram negative rods
susceptible to hydrolysis by B-lactamase
MECHANISM OF ACTION
bactericidal-
Penicillins
2
inhibit bacterial growth through interfering with the transpeptidation reaction
of bacwall syntesis
RESISTANCE
1. inactivation of antibiotic by B-lactamase- most common mechanism of resistance
2. modification of target PBPs
3. impaired penetration of drug to target PBPs- only in gram. negative
4. antibiotic efflux
CLINICAL USES
should be given 1-2 hours before or after meal, except for amoxicillin
do not use fruit juices, soft drinks, milk
Penicillin
A. Penicillin G
streptococci
meningococci
some enterococci
penicillin-susceptible pneumococci
staphylococci confirmed to be non-β-lactamaseproducing,
Treponema pallidum
spirochetes,
some Clostridium species,
Actinomyces
and certain other Grampositive rods,
and non-β-lactamase-producing Gram-negative anaerobic organisms.
B. Penicillin V
Penicillins
3
oral form
minor infections
poor bioavailability
4 x a day
Penicillins Resistant to Staphylococcal
BetaLactamase (Methicillin, Nafcillin, and
Isoxazolyl Penicillins)
Listeria monocytogenes
enterococci
methicillin-resistant strains of S. aureus
diclocaxillin- treatment of mild to moderate Staphylococcal infections
Extended-Spectrum Penicillins
(Aminopenicillins, Carboxypenicillins, and
Ureidopenicillins)
have greater activity against Gram (-) bacteria
inactivated by B-lactamases
amoxicillin - absorbed orally to treat bacterial sinusitis, otitis, lower
respiratory tract infection
Ampi and amoxocillin - oral B-lactam antibiotics against pneumococci
ampicillin- shigellosis (diarrhea)
cannnot be used for UTI and typhoid fever
enterococci
L. monocytogenes
E. coli
Salmonella sp/
Penicillins
4
ADVERSE REACTIONS
1. hypersensitivity - Type 1 hypersensitivity skin testing
2. anaphylactic shock
3. pts. with renal failure —> seizures
4. Nafcillin - neutropenia and interstitial nephritis
5. Oxacillin- hepatitis
6. Methicillin- interstitial nephritis
7. Ampicillin - pseudomembranous colitis
DRUG-DRUG INTERACTIONS
w/ tetracylcines —> decrease in effectiveness
parenteral penci + parenteral aminoglycosides = inactivation of aminoglycosides
(SHOULD BE AVOIDED)
Penicillins
5