Beta Lactum Flashcards
All beta lactam have in their structure?
a beta-lactam ring
The antibiotics under this group consist of:
Penicillins.
Cephalosporins.
Carbapenems.
Monobactams
Source
Natural: from molds (Fungi) only penicillin G and Penicillin V
Semisynthetic.
Disadvantages of penicillin G
1- Acid-sensitive -Can’t be Taken otally
2) B-lactamase - sensitive
3) Narrow-spectrum
4- short acting
To solve acid resistance
Penicillin v
To solve B lactamase resistance
Methicillin
To solve short acting
a. Procaine penicillin G/ 12h.
b. Fortified Procaine Penicillin G/ 24h and quick onset.
c. Benzathine Penicillin G/ month.
To solve narrow spectrum
- Ampicillin -> incomplete oral absorption ( short duration)
- Amoxicillin-> complete oral absorption
- Pro- ampicillin
Short acting can be Long actin when we increase
Frequency
Absorption
According to preparations
Penicillin V , ampicillin and amoxicillin -> absorbed orall
Distribution
No pass B.B.B Pass easily inflamed meanings.
Pass placenta barrier but has no negative effects ( not teratogenic )
Metabolism
Metabolized by bacterial enzymes:
Penicillinase~ Penicilloic acid ~ Inactive & Hapten causes allergic reactions.
What hapten do ?
Allergic reactions
Side effects
Ampicillin causes “maculopapular rash”
Jarisch-Herxheimer reaction
Diarrhea and superinfection.
Case of maculopapular rash
Allergy.
b) Leukemia.
c) Infectious mononucleosis (diagnostic test).
d) Patients treated by allopurinol.
Cause of Jarisch-Herxheimer reaction
Due to syphlitis
Indication
- Respiratory tract infections TB
2) unnary tract infections
3) G I T infections
4) Meningitis
5- Endocarditis.
6-Syphilis
Lactamase inhibitors
1.Ampicillin+ Sulbactam forms Unasyn
2. Amoxycillin + clavulanic acid forms Augmentin and Hibiotic.
Mechanism of action
- Bactrio static -> (prevent growth and
Reproduction )
2.Bactericidal: Kills the bacteria
#Penicillins bind to specific penicillin binding proteins (PBPs) that inhibits transpeptidase enzyme leads to inhibition of cross linking between peptidoglycan layers causing inhibition of cell wall synthesis
Cephalosporins
Source and chemistry
as Penicillin
Cephalosporins
Source and chemistry
as Penicillin
Lactamase producing bacteria are PEPSI
Proteus,
E. Coli,
Pseudomonas,
Staph
H. Influenza).
Spectrum
Broad
Spectrum
Broad
excretion of Cephalosporins
Active Renal tubular excretion
Distribution of
Cannot pass b.b.b
Exception in execration of Cephalosporins
1.Cefotaxime is Partially’ de-acetylated & partially excreted unchanged in urine.
2. Ceftriaxone & Cefoperazone undergo Biliary excretion.
Adverse effects of Cephalosporins
1.Hypersensitivity: as penicillin.
2. Diarrhea and superinfections: as penicillin.
3.Never give ceftriaxone and Ca in same line as may form insoluble salt causing biliary stones
4. Nephrotoxicity; especially if given with aminoglycosides
First generation members ( cannot pass 3B)
Cephalexin
Cephradine.
Cefazolin
Cefapirin
Second generation members ( cannot pass 3B) except …
Cefuroxime
cefaclor.
Cefuroxime
cefamandole
Cefoxitin
Except (Cefuroxime)
Third generation members ( pass3B) except
Except cefoperazone.
1. Cefixime
2. Cefotaxime
3. Ceftriaxone
4. Cefoperazone
5. Ceftazidime
6. Moxalactam.
Fourth generation members
Cefepime
Imipenem source and chemistry
Synthetic
β Lactam antibiotics.
Imipenem distribution
Given IV and Pass BBB during meningitis.
Adverse effect of Imipenem
Allergy and partial cross-allergy with penicillin, GIT disturbances and seizures
Indication of Imipenem
sserious hospital acquired (Nosocomial) infections.
How to make imipenem safe for kidney
Imipenem + Cilastatin forms Tienam
Why Imipenem nephrotoxic
due to dihydropeptidase enzyme
Benefits of meropenem
Not nephrotoxic
Rare To produce seizures
Ertapenem benefits
has longer half life (given once/lay]
→ Doesn’t produce Seizures
→not nephrotoxic
