Antibiotic Proliferation

There is a staggering array of antibiotics available to the modern clinician, from the old standby, penicillin, to the newest antibiotic available. “Old” antibiotics, penicillin and the sulfonamides, are effective most of the time in treating routine outpatient infections.^[38] When enough infections that don’t respond to the ‘old standbys’ arise, new antibiotics soon follow.

Between 1945 and 1968, drug companies invented 13 new categories of antibiotics, but between 1968 and today, just two new categories of antibiotics have been added. According to the National Institutes of Health the lack of new antibiotics is threefold:^[39]

• There is not much money in it;
• Inventing new antibiotics is technically challenging;
• In light of drug safety concerns, the FDA has made it difficult for companies to get new antibiotics approved.

Antibiotics come in numerous “flavors,” there are hundreds of types and brands of antibiotics. These antibiotics each have a unique purpose in medicine and many have been developed strictly to replace an out-dated brand that no longer works.  The different categories of antibiotics in use today are:^[40]

• Penicillins
• Cephalosporins
• Carbapenems
• Macrolides
• Aminoglycosides
• Quinolones (Fluoroquinolones)
• Sulfonamides
• Tetracyclines
• Other Antibiotics

Each one of these categories has possibly dozens of different generic types and even more brand names associated with it.  For instance, penicillin, not the largest category by any means, but quite impressive:

Penicillins

Generic	Brand Name
Amoxicillin	Amoxil, Polymox, Trimox, Wymox
Ampicillin	Omnipen, Polycillin, Polycillin-N, Principen, Totacillin
Bacampicillin	Spectrobid
Carbenicillin	Geocillin, Geopen
Cloxacillin	Cloxapen
Dicloxacillin	Dynapen, Dycill, Pathocil
Flucloxacillin	Flopen, Floxapen, Staphcillin
Mezlocillin	Mezlin
Nafcillin	Nafcil, Nallpen, Unipen
Oxacillin	Bactocill, Prostaphlin
Penicillin G	Bicillin L-A, Crysticillin 300 A.S., Pentids, Permapen, Pfizerpen, Pfizerpen-AS, Wycillin
Penicillin V	Beepen-VK, Betapen-VK, Ledercillin VK, V-Cillin K
Piperacillin	Pipracil
Pivampicillin
Pivmecillinam
Ticarcillin	Ticar

Despite all these categories and types, all antibiotics fall into one of two classifications: bactericidal and bacteriostatic.

Bactericidal antibiotics kill invading bacteria while bacteriostatic antibiotics stop new bacteria from being created. Bactericidal antibiotics include the cephalosporins and penicillins. Bacteriostatic antibiotics include tetracyclines and sulfonamides. The many variations seen and even synthetic creations are a result of the resistance that rapidly develops when a new antibiotic is unleashed on the public.


Special thanks to Dr. Grace Liu, PHARMD, from Animal Pharm for contributions to this article.

[38] Davies, J. "Antibiotic Resistance: Origins and Countermeasures ..." 2010. <http://www.ncbi.nlm.nih.gov/books/NBK45710/>

[39] Brian Vastag. "NIH superbug outbreak highlights lack of new antibiotics ..." 2012. 3 May. 2014 <http://www.washingtonpost.com/national/health-science/nih-superbug-outbreak-highlights-lack-of-new-antibiotics/2012/08/24/ec33d0c8-ee24-11e1-b0eb-dac6b50187ad_story.html>

[40] "List of Antibiotics - eMedExpert.com." 2007. 3 May. 2014 <http://www.emedexpert.com/lists/antibiotics.shtml>