Download Antibacterial Drugs:

Antibacterial Drugs:
**Mechanisms of action
( site of action )
1. Nucleic acid synthesis inhibition:
e.g
Sulphonamides, trimethoprim,
quinolones, nitrofurantoin,
refampicin.
• 2.Protein synthesis
inhibition:e.g.
• Macrolides,
aminoglycosides,
Chloramphenicol,
tetracycline
3. Cell wall synthesis inhibition:
e.g
Vancomycin, cephalosporins,
penicillins
**
The β – lactam antibiotics:
• These are the pencillines
and cephalosporines
whose basic structure
include β – lactam ring
Resistance is commonly due
to bacterial enzyme called β –
lactamases (( pencillinase and
cephalosporinase )) which can
cleave the ring and inactivate
the antibiotic.
** The penicillins:
• All penicillins are bactericidal with
wide range of activity for both
gram +ve and certain gram –ve
organism
• It should never given
interathecally
Their adverse effects include:
•
•
•
•
•
skin rash
anaphylaxis
drug fever
interstitial nephritis
haemolysis
** Benzylpenicllin:
• It is rapidly absorbed following
intramuscular injection and
excreted by the kidneys withen
few hours and addition of
probenecid will delay its
excreation and allow smaller
doses with less frequent
** Procain
Penicillin:
• addition of procainamide,
• given i.m,
• Active against: streptococci,
meningococci, anthrax,
tetanus, syphilis and
diphtheria.
** Phenoxymethyl
penicillin
(( Penicillin V ))
• Incompletely absorbed
from the stomach
• Active against:
streptococci
.
** Cloxacillin & flucloxacillin
• They are stable to
staphylococcal β – lactimases
• For oral therapy flucloxacillin is
superior to cloxacillin
** Temocillin:
•It is active against
pencillinase producing
gram –ve bacilli.
** Ampicillin;
• It has a bactericidal action against
both gram +ve and certain gram –ve
organisms
• It is susceptible to degradation by β –
lactimase and not well absorbed with
food.
• Skin rash in patients with infectious
mononucleosis
** Amoxycillin:
• It is an analog of ampicillin
which has similar
antibacterial spectrum but it
is more reliably absorbed
from GIT
** Augmentin
• It is a combination of amoxicillin
and sodium clavulanate
• Clavulanic acid is a potent
inhibitors for many β –
lactemases and it can protect
amoxicillin from inactivation by
them.
** Ticarcillin:
• It is an analogue of carbencillin
with more activity against
Pseudomonus spp.
• A combination of ticarcillin and
clavulanic acid is called
Timentin.
** Mezlocillin,
azlocillin
and pipracillin;
• They have a wider range
of activity and more
effective against many
gram –ve bacilli.
The Cephalosporins;
• 1st generation e.g cephalexin, cephradin
• 2nd generation e.g cephaclor, cefuroxime
• 3rd generation e.g cefotaxime,
cephitrixone
• 4th generation e. g cefepime, cefpirome
• Wide range of activity
• 10 % of penicillin sensitive may als allergic
to them
**
Imipenem:
• Β- lactam antibiotic with a
very broad spectrum which
include aerobic and
anaerobic gram +ve and
gram –ve organisms.
The Macrolide
antibiotics
** Erythromycin:
• Used in treatment of infection caused by
gram +ve organisms in penicillin allergic
patients.
• It is effective in Whooping cough,
pneumonia, mycoplasma and Chlamydia.
• S/E : diarrhea, vomiting, abdominal pain,
and cholestatic jaundice.
**Clarithromycin:
• Greater activity than
erythromycin and higher
tissue concentration
** Azithromycin:
• More activity against
gram –ve organisms
including H. Influenzae.
** Spiromycin:
• A macrolide used in treatment of
Txoplasmosis.
• The Tetracyclines: is a bacteriostatic
agent used in Brucellosis,
mycoplasma, typhus fever, Q – fever
• It should not prescribed for pregnant
female, children and patients with
renal failure.
The aminoglycosides:
• They include gentamycin, streptomycin,
amikacin
• Active against gram –ve bacilli
• Streptomycin has anti TB and used in
treatment of Brucellosis
• They are nephrotoxic and ototoxic
• Neomycin is too toxic to be given
parantraly and used orally in hepatic
encephalopathy.
*** Chloramphenicol:
• It is effective in enteric fever and against
H. Influenzae
• It may cause pancytopenia
• It should never be given to premature
infant or to the newborn because of the
risk of development of gray baby
syndrome.
*** Clindamycin / Lincomycin
• Effective against most gram +ve
organisms including penicillin resistant
staphylococci
• It pentrate well into bones so it is useful for
osteomyelitis and effective in lung abscess
• Common cause of pseudomembranous
colitis
** Sodium
fusidate
• It is useful in infection caused
by penicillin resistant
staphylococci
• It is well absorbed and the oral
rout can be used instead the
parenteral rout
**
Spectinomycin
• Used for treatment of
gonorrhoea if penicillin is
contraindicated because
of allergy or bacterial
resistance.
Vancomycin and teicoplanin:
• Used for serious staphylococcal
infection including methicillin
resistant and it is used in
antibiotic associated colitis.
• They are nephrotoxic and ototoxic
** Sulphonamides/
Trimethoprim / Co – trimoxazol
• Used in treatment of cystitis,
UTI, typhoid fever and
pneumonia
• S/E skin rash, nephritis and
haemolysis
*** Quinolone antibiotics
• Ciprofloxacin is the most important one
• Effective against aerobic gram –ve bacilli.
• Used in treatment of typhoid fever, UTI,
gonorrhoea
• They are contraindicated in children and
pregnancy
** Metronidazole
• Effective against anaerobic
bacteria and intestinal
protozoa e.g Giardia
Lambelia and Entameba
histilytica.
** Tinidazole
•It is similar to
metronidazole but
with longer half life
*** Antituberculous
• Refampicin,
• INH,
• Pyrazinamide,
• Ethambutol and
• Streptomycin
drugs
*** Antifungal
drugs
• For topical application:
Nystatin, Clotrimazol
• For oral administration:
Ketoconazole, Grisofulvin
• For intravenous infusion:
Amphotericin, Flucytocin
*** Antiviral drugs
• Acyclovir: effective against herpes simplex and H.
zoster
• Famciclovir: antiherpes agent with activity against E
B virus and hepatitis B virus
• Ganciclovir: antiherpes agent with activity against
cytomegalovirus
• Amantadine: used for prophylaxis of influenza A.
• Ziduvidine used for HIV infection.
• Ribavirine: against RNA viruses e.g Influenza, RSV
Antiparasitic drugs:
• Antimalarial: Chloroquine,
premaquine, proguanil
• Anti intestinal protozoa:
Metronidazole, tinidazole
• Antihelmenth drugs: Mebendazole,
Albendazole
• Antibilharzial agents: Praziquantel.