文档介绍：Antibiotic drugs
Among the hundreds pounds produced by anisms that have inhibitory action on other anisms, only a relatively small number have a favorable therapeutic index. These are the clinically useful antibiotics. In the present discussion, particular attention will be paid to the potency, antibacterial spectrum, metabolism, and mode of action of these various antibiotic drugs.
Penicillin is a highly effective bactericidal antibiotic which has very low toxicity. If it were not for penicillin allergy, the antibiotic would approach perfection for infections caused by anisms. Penicillin is obtained from cultures of Penicillin chrysogenum. The semisynthetic penicillins are made by modification of the mold product.
Penicillin is anic acid. Its sodium, potassium, and procaine salts monly used. There are several other naturally occurring penicillins that differ from penicillin G in having a side chain other than benzyl. Some of these are penicillin F, dihydro F (amylpenicillin), and also K and X. None of these naturally pounds has a significant advantage over penicillin G, and some, such as K, may be much less effective in vivo because of a high degree of plasma protein binding.
Although several biosynthetic penicillins have been prepared by adding various precursors of the side chain to the Penicillium culture medium, more recently anew procedure has opened up a field for the preparation of new penicillins. A key intermediate, 6-aminopenicillanic acid, is produced by fermentation, and new penicillins are prepared by adding various groups to this intermediate.
Penicillin has pletely synthesized through cooperative efforts of several groups of workers. Total synthesis is much too difficult mercial production.
The available penicillins may be placed in several groups. Penicillin G, or benzylpenicillin, is the prototype. Semisynthetic penicillins, which have a broader antibacterial spectrum but are still susceptible to penicillinase, represent an important group. O