Penicillin and Macrolides

Only available on StudyMode
  • Download(s) : 478
  • Published : March 5, 2012
Open Document
Text Preview
Course: Drug DevelopmentModule code: MT 5004Assignment: Essay 1|

Penicillin and Macrolides – The ANTIBIOTICS
Penicillin and Macrolides, each having different properties belong to the same group of medicine called ANTIBIOTICs. Antibiotics refer to the chemical substance secreted or produced by various species of micro-organisms which are capable of inhibiting or killing the bacteria. Antibiotics have enabled the effective treatment of infections including life threatening diseases ranging from respiratory diseases to sexually transmitted diseases (Rang et al.,2007). An antibiotic acts by either limiting or stopping the growth of bacteria. It accomplishes this by probably interfering with the cell wall of the bacteria while having minimal effect on the normal body cells. Classifying bacteria into classes helps in identifying the bacterial species and hence they are classified as gram positive bacteria and gram negative bacteria based upon their staining techniques. Penicillin is the oldest and the best known antibiotic. Basically, it is an antibiotic compound derived from the moulds Penicillium notatum and Penicillin chrysogenum and is active in opposition to gram positive bacteria and few gram negative bacteria. Penicillin turns out to have two rings fused together; one being the β-lactam ring and the other Thiazolidine ring (Ref figure 1) ( β-Lactam Antibiotics: Penicillins). |

Figure 1: General Structure of Penicillin|

All Penicillins have the same fundamental structure, only the group R varies. Penicillin is generally classified as bio-synthetic and semi-synthetic. Bio-synthetic refers to the naturally occurring penicillin. These are the very first agents in the family of penicillin introduced for clinical use. They include Penicillin G, Penicillin V and Benzyl Penicillin. These prove to be effective against Gram positive bacteria like meningococcus and also prove useful in patients with oral-cavity infection. Certain chemical alterations in the structure of naturally occurring penicillin results in formation of semi-synthetic penicillins. For example, penicillin V is made by replacing the -CH2C6H5 group in natural penicillin G with -CH2OC6H5 group. The semi-synthetic class consists of Penicillinase-resistant penicillin and Aminopenicillins. The Penicillinase-resistant penicillin includes Cloxacillin, dicloxacillin, methicilin and Nagcillin while the Aminopenicillins consists of Ampicillin, Amoxocillin and Bacampicillin. Penicillinase-Resistant Penicillin provides a narrower antibacterial spectrum of activity than the natural ones. Aminopenicillins are known to be active against the gram negative bacteria like E. Coli and are used to treat mild infections like sinusitis and bronchitis. The further classified Extended Spectrum Penicillin provides additional action against the gram negative bacteria (Chain, 1945). Macrolides which are also anti bacterial antibiotics are often used in patients appearing sensitive to penicillin. These are bacteriostatic and work by inhibiting the synthesis of vital proteins in bacteria. The Macrolides were isolated from Streptomyces bacteria, and got their name because they have a macrocyclic lactone chemical structure, also called the macrolide ring. The macrolide molecules are made up of large-ring lactones to which one or more deoxy sugar(s) is attached. Also they can be 14/15/16 membered (refer table 1). Erythromycin is the best known medicine in this group. Newer members of the group, azithromycin and clarithyromycin, are particularly useful for their high level of lung penetration. Clarithromycin has been widely used to treat Helicobacter pylori infections, the cause of stomach ulcers (Chain, 1945). Table 1: Classification of Macrolides depending upon the size of their rings 14- membered ring| 15-membered ring| 16 membered ring|

Erthyomycin| Azithromycin| Josamycin|
Roxithromycin| | Spiramycin|
Clarithromycin| | Micomycin|
Dirthromycin| | |

tracking img