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What Is the Difference Between Penicillin & Amoxicillin?

author image Kathleen Blanchard, R.N.
Kathleen Blanchard is a registered nurse, with more than 10 years of experience in cardiovascular health, emergency room and ICU. She writes professionally for Emaxhealth.com. and AskMen.com. Blanchard is currently employed as a senior case manager and has held certification as a critical care registered nurse (CCRN), advanced trauma life support (ATLS), and advanced cardiac life support (ACLS).
What Is the Difference Between Penicillin & Amoxicillin?
What Is the Difference Between Penicillin & Amoxicillin? Photo Credit www.fotosearch.com

Penicillin is an antibiotic, as is amoxicillin. The difference between the two is subtle. Penicillin is synthetically produced. Amoxicillin is a semi-synthetic penicillin drug. Amoxicillin might be considered an improved form of penicillin. Both drugs are used to treat a wide array of infectious diseases. Amoxicillin is used more often than penicillin to treat diseases because it has been shown to be more effective for eradicating some infections than the original penicillin. Amoxicillin has the ability to withstand stomach acid, releasing more antibiotic into the blood stream. Penicillin is not as well absorbed as amoxicillin.

Amoxicillin Is More Effective Than Penicillin

According to a 1996 study published in "The Pediatric Infectious Disease Journal," children with pneumonia were found to respond to oral amoxicillin as well as those who were hospitalized and given intravenous penicillin. Comparison of amoxicillin and penicillin produced the same outcomes. Treating children at home with oral amoxicillin was concluded to be more desirable than the trauma of hospitalization.

The semi-synthetic nature of amoxicillin makes it better able to penetrate the walls of certain bacteria, compared to penicillin, which is synthetic. Amoxicillin, compared to penicillin, kills a wider array of bacteria. Bacteria killed by penicillin do not respond any differently to amoxicillin--both are equally effective against some bacteria.

Amoxicillin Can Be Taken for a Shorter Period of Time

Amoxicillin does not have to be taken as long as penicillin. It does the job in a shorter period of time. A study published June 2007 in the journal "Thorax" compared amoxicillin and penicillin for treatment of strep throat. The study authors concluded, "The efficacy and safety of amoxicillin--50 mg/kg/day twice daily--for 6 days were not statistically different from those of penicillin--45 mg/kg/d three times a day--for 10 days in the treatment of GAS tonsillopharyngitis."

Amoxicillin and Penicillin Both Come From Mold

Penicillin and amoxicillin essentially do the same job. Both drugs are produced from the mold penicillium. The antibacterial properties of synthetic penicillin, later leading to development of semi-synthetic amoxicillin, came about in 1928 when Alexander Fleming accidentally found that penicillium mold could destroy bacteria.

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