MONOBACTAMS AND TRIBACTAM



MONOBACTAMS
Developed in response to a desire for specific drugs aimed at gram  negative bacteria (as opposed to broad acting antibiotics).  Eg: aztreonam, tigemonam 
Aztreonam only binds to gram negative PBP. 
It has no real beta-lactam ring  and hence is  very beta-lactamase stable. 
These drugs have a very narrow spectrum and are useful only against aerobic gram negative organisms, but they can be used instead of aminoglycoside drugs (which also work against gram negative bacteria) because of their far less nephrotoxic side-effect profile
 Aztreonam: This drug is a monocyclic beta-lactam (a monobactam).  
Aztreonam interacts with penicillin binding proteins and induces the formation  of long filamentous bacteria.
Antimicrobial spectrum: The antimicrobial spectrum of aztreonam differs from that of other beta-lactams. It more closely resembles the spectrum of the aminoglycosides. Gram positive and anaerobic bacteria are resistant. Susceptible organisms include:  (It has an unusual spectrum being active only against Gram-negative aerobic rods) Enterobacteriaceae, Pseudomonas, Hemophillus and Neisseria. Aztreonam is resistant to the beta-lactamase produced by gram negative organisms.
Side effects:
Generally, the drug is well tolerated. Patients who are allergic to penicillins do not exhibit cross-reactions with aztreonam.
Toxicity is similar to that of benzyl penicillin, with no apparent cross allergy.   
These do not cause the gastrointestinal disturbances associated with carbapenems and other broad spectrum beta lactam antibiotics. 
Their inactivity against gram positive bacteria may lead to superinfection with yeasts and gram positive aerobes including Enterococcus   spp.and S.aureus
The empirical dose in animals is 30-50mg/kg,IV every 8 hours. 
It is  used in a wide variety of iinfections involving gram negative bacteria (urinary tract, lower respiratory tract, septicemia) with success as  relatively nontoxic drug in human medicine

TRIBACTAMS
They have a tricyclic structure related to that of carbapenems. 
Sanfeterinem cilexetil is the prodrug of sanfetrinem.
It has high stability to many beta lactamases and a broad spectrum of activity similar to that of carbapenems.

Comments

Post a Comment

Popular posts from this blog

Skeletal muscle relaxants

Image
Skeletal muscle relaxants Physiology of SKM Contraction 1. Motor nerve impulse à 2. Release of ACh à 3. Binds with N M receptors at NMJ à 4. Depolarization & development of EPP at motor end plate (Mainly due to influx of Na + ) à 5. Muscle action potential (MAP) – contraction of SKM à 6. ACh is rapidly inactivated by ChE leading to repolarization à 7. Muscle is ready for a fresh nerve impulse. MECHANISM OF ACTION OF MUSCLE RELAXANTS Centrally acting muscle relaxants -           Reduce SKM tone by a selective action in the cerebrospinal axis, without altering consciousness. -           They selectively depress spinal and supraspinal polysynaptic reflexes involved in the regulation of muscle tone without significantly affecting monosynaptically mediated stretch reflex. -           Polysynaptic pathways in ascending reticula...
Read more

CNS Stimulants

CNS Stimulants The CNS stimulants are classified into three major categories a.        Cortical stimulants b.       Medullary stimulants c.        Spinal stimulants Cortical stimulants These are further divided into three types 1.        Classical cortical stimulants – Cocaine, Xanthines, Ephedrine and Amphetamine 2.        Psychotomimetics – Lysergic acid 3.        Antidepressants (Thymoleptics) – Imipramine , tranylcypramine and Isoniazid. Classical cortical stimulants ·          Cocaine, Amphetamine, Ephedrine and Xanthine are cortical stimulants. ·          These drugs affect mainly the sensory cortex but the motor cortex is also stimulated with high dose. Cocaine ·     ...
Read more

Pharmacokinetics - Drug absorption and Transport of drugs across biological membranes

Transport of drugs across biological membranes All pharmacokinetic processes involved transport of the drug across biological membranes. Biological Membrane Biological membranes may be viewed as mosaics of functional units composed of lipoprotein complex. Most membranes are composed of a fundamental structure called the unit membrane or plasma membrane. This boundary, which is 80 to 100 A° thick, surrounds single cell and nuclei. More complex barriers such as the intestinal epithelia and the skin are composed of multiples of this functional structure. The plasma membrane consists of a bilayer of amphipathic lipids with their hydrocarbon chains oriented inward to form a continuous hydrophobic phase and their hydrophilic heads oriented outward. Individual lipid molecules in the bilayer can move laterally, endowing the membrane with fluidity, flexibility, high electrical resistance and relative impermeability to highly polar molecules. The known fluidity of the phospholipids i...
Read more