MEDORG-SEMIFINALS-ANTIBACTERIALS

Antibacterials

• substance produced by microorganisms which has the capacity to inhibit the growth and to cause the destruction of other microorganisms

Bacteriostatic and Bactericidal

Types of Antibacterials:

Penicilin

• MOA: interfere with the last step of bacterial cell wall synthesis

• cross-linking of peptide bond

• Beta-lactam attached to thiazolidine ring

Pen G and Pen V

• Natural penicillins:

Benzyl Penicillin (Pen G)

• poorly absorbed from the intestinal tract, oral doses must be large

• not effective orally; IM only not IV or SQ

• its rapid elimination form the bloodstream led to the development of repository forms

Pen G procaine and Pen G Benzathine

• Repository forms of Pen G:

Penicillin V

• acid stable

Anti-staphylococcal/Penicillinase resistant penicillins

• narrow spectrum

Methicillin

• off the market due to high incidence of Interstitial nephritis

Isoxazolyl Penicillins

• relatively small amounts are excreted through kidneys, with the major portion excreted in the bile

• can be given to patients with renal problems

Aminopenicillins

• have an antibacterial spectrum similar to that of Pen G but are more effective against gram (+) bacilli

Ampicillin

• poor GI absorption; more frequently administered parenterally

Amoxicillin

• better GI absorption than ampicillin

Bacampicillin

• prodrug of ampicillin

Carboxypenicillins

• against: pseudomonas aeruginosa, enterobacter, proteus, bacteroides

Ticarcillin + Clavulanic acid

• 2 to 4 times as active as carbenicillin against pseudomonas aeruginosa

Ureidopenicillins

• against Klebsiella

Piperacillin + tazobactam

• 10 times as active as carbenicillin against pseudomonas

Cephalosporins

• beta-lactam attached to dihydrothiazine ring

Monobactam

• the beta-lactam ring is not dused to another ring

Aztreonam

• bactericidal

• active against many gram negative organisms, including Enterobacter and P. aeruginosa

Carbapenems

• broadest in activity

• resistant to beta-lactamases

Vancomycin

• effective against MRSE/MRSA

Vancomycin

• used for potentially life-threatening antibiotic associated colitis due to Clostridium difficile

Vancomycin

• slow intravenous infusion is employed for treatment of systemic infections

Vancomycin

• AE: flushing (red man syndrome or red neck syndrome)

Bacitracin

• from Bacillus subtilis

• cyclic peptide or a mixture of polypeptide

• active against a wide variety of gram (+) organisms

Polymyxin

• effective primarily against gram (+) organisms

Gramicidin

• useful against gram (-) organisms

mycin

• derived from Streptomyces

micin

• derived from Micromonospora

Aminoglycosides

• the highly polar structure of aminoglycosides prevents adequate absorption after oral administration

Aminoglycosides

• are so named because their structures consist of amino sugars linked glycosidically

• effective against psuedomonas, acinetobacter, enterobacter

Tetracycline

• broades spectrum antibiotic

• has activity against gram (+), gram (-), spirochetes, mycoplasma, ricketssia, and chlamydia

Tetracycline

• the hydrochloride salts content are used most commonly for oral administration and usually are encapsulated because they are bitter

Chloramphenicol

• unclassified antibiotic

• DOC for typhoid fever

Chloramphenicol Palmitate

• palmitic acid ester of chloramphenicol

• a tasteless prodrug of chloramphenicol intended for pediatric use

Chloramphenicol sodium succinate

• the water soluble sodium salt of hemisuccinate ester of chloramphenicol

• because of its low solubility, is preferred for intravenous administration

Macrolides

• spectrum of activity resembles pen G but also effective against mycoplasma, chlamydia, campylobacter and legionella

Erythromycin

• formerly Ilotycin

• alternative to penicillin

Erythromycin

• esters of erythromycin base (e.g., stearate, estolate, and ethylsuccinate) have improved acid stability, and their absorption is less altered by food

Clarithromycin

• more potent than erythromycin against streptococci and staphylococci

Azithromycin

• once a day dosing

• the elimination half-life, 40 to 68 hours, is prolonged because of extensive tissue sequestration and binding

Clindamycin

• one of the most potent agents available against non-spore forming anaerobic bacteria (Bacteroides fragilis)

Quinolones

• pattered after nalidixic acid (inhibits multiplication of bacteria and is used for UTI)

• the introduction of fluorine atom forming fluoroquinolones enhances antibacterial activity

Ciprofloxacin

• is the most potent fluoroquinolone

Nitrofurantoin

• the first nitroheterocyclic compounds to be introduced into chemotherapy

• used as an antiprotozoal agent

Metronidazole

• the most useful of a group of antiprotozoal