Penicillins second generation

From WikiMD's Wellness Encyclopedia

(Redirected from Metacillin)

Information about Penicillins second generation[edit source]

The penicillinase-resistant [also referred to as second generation penicillins] are semisyntheic modifications of natural penicillins that are resistant to bacterial enzyme beta-lactamase, which accounts for typical penicillin resistance.

Mechanism of action of Penicillins second generation[edit source]

The natural penicillins from which the second generation penicillins are made are bactericidal antibiotics naturally derived from the mold, Penicillium chrysogenum. Their basic structure includes a thiazolidine ring connected to a beta-lactam ring with a variable side chain. As a class, the penicillins bind to bacterial proteins and inhibit synthesis of the bacterial cell wall, causing cell lysis particularly in rapidly growing organisms. Bacterial resistance to penicillin is usually mediated by beta-lactamase, an enzyme which destroys the beta-lactam ring of penicillin, rendering it inactive. The penicillinase-resistant penicillins resist the hydrolysis of the beta-lactam ring by the bacterial enzymes. They are active against most organisms that are susceptible to the natural penicillins (although less active than penicillin G) and have extended coverage against resistant forms.

Mechanism of action of Penicillins second generation[edit source]

Three major penicillinase-resistant penicillins are available in the United States: dicloxacillin (dye klox" a sil' in), oxacillin (ox" a sil' in) and nafcillin (naf sil' in).

  • Dicloxacillin is orally available; oxacillin and nafcillin have both oral and parenteral formulations, the latter being given by the intramuscular or intravenous route. Other formulations available abroad or in the past include methicillin, cloxacillin and flucloxacillin, which have been associated with a higher frequency of side effects including hepatic injury.


The major indications for dicloxacillin, oxacillin and nafcillin are moderate-to-serious infections with susceptible penicillinase-producing staphylococci; these agents are also active against organisms susceptible to natural penicillins, but are less active than the natural penicillins.


Penicillin antibiotics[edit source]

Penicillins second generation Resources
Wikipedia
WikiMD
Navigation: Wellness - Encyclopedia - Health topics - Disease Index‏‎ - Drugs - World Directory - Gray's Anatomy - Keto diet - Recipes

Search WikiMD

Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD

WikiMD's Wellness Encyclopedia

Let Food Be Thy Medicine
Medicine Thy Food - Hippocrates

Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.

Contributors: Prab R. Tumpati, MD