How and where is penicillin made

PenicillinsDrug groupsAntibioticsBeta-lactam antibioticsPenicillins are bactericidal active ingredients from the group of beta-lactam antibiotics, which are used for the treatment of bacterial infectious diseases. Natural penicillin comes from molds of the genus Penicillium and was discovered in London in 1928. It was used therapeutically from the 1940s. The effects are based on the inhibition of bacterial cell wall formation. Due to the short half-life, the drugs usually have to be administered several times a day. The most common adverse effects include gastrointestinal upset, allergic reactions, and skin rashes.

synonymous: penicillin antibiotics


Penicillins are now available in the form of film-coated tablets, capsules, solutions for injection and infusion, as powders for the preparation of an oral suspension and as syrups.

Penicillin was discovered by Alexander Fleming at St. Mary's Hospital in London in September 1928. He worked with staph cultures in petri dishes. One of the plates was covered with mold (Penicillium) has been contaminated. In the vicinity of the fungal colony, the staphylococci became transparent and dissolved. So the fungus formed a substance that killed the bacteria. Fleming called it penicillin.

The group led by Howard Florey and Ernst Boris Chain at Oxford University later succeeded in purifying, isolating and producing the antibiotic. Penicillin was first produced on a large scale in the USA in the 1940s and used to treat infections. Penicillin G (benzylpenicillin) is one of the earliest and natural penicillins. By varying the fermentation medium, different active ingredients could be obtained.

Structure and properties

The basic structure of penicillins is 6-aminopenicillanic acid, which consists of a thiazoline ring and a beta-lactam. Cyclic amides are called lactams. The 6-aminopenicillanic acid is made up of the two amino acids cysteine ​​and valine.

The older penicillins such as benzylpenicillin are acid-labile and can therefore only be administered parenterally. Acid-stable oral penicillins have been developed that are also available orally, such as the aminopenicillin amoxicillin. By modifying the side chain, the properties of the natural penicillins could be changed decisively (see below).


Penicillins (ATC J01C) have antibacterial properties against gram-positive and sometimes also against gram-negative pathogens. They inhibit bacterial cell wall synthesis by binding to so-called penicillin-binding proteins (PBP). The PBP includes the D-Ala-D-Ala transpeptidase, which is involved in the synthesis of the peptidoglycan. Penicillins are so-called suicide inhibitors because they irreversibly bind to the enzymes by opening the beta-lactam ring.

Mechanism of action of penicillins, click to enlarge. Illustration © PharmaWiki


For the treatment of bacterial infectious diseases with sensitive pathogens.


Because of their short half-life, penicillins usually have to be administered several times a day or as an infusion.

Active ingredients

The following active ingredients are currently registered as human medicinal products in Switzerland:

There are also numerous other penicillins, such as ampicillin.

Classification of penicillins

Penicillins are divided into different groups. They arise from the variation of the side chain:

  • Natural penicillins like benzyl penicillin are derived from Penicillium-Species (Penicillium chrysogenum).
  • Oral penicillins such as amoxicillin are orally bioavailable and can be taken e.g. in the form of tablets or as a suspension.
  • Acid-stable penicillins such as phenoxymethylpenicillin remain stable on contact with gastric acid.
  • Penicillinase-resistant penicillins such as oxacillin and flucloxacillin are resistant to penicillin-degrading enzymes in bacteria.
  • Aminopenicillins such as ampicillin and amoxicillin carry an amino group.
  • Broad-spectrum penicillins such as piperacillin have a broader spectrum of activity than the early active ingredients, e.g. also against pseudomonads.

Some penicillins are combined with beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam to reduce resistance and increase effectiveness.


Penicillins are contraindicated in case of hypersensitivity, including to other beta-lactam antibiotics. The complete precautionary measures can be found in the medicinal product information sheet.


Penicillins are organic anions and are actively secreted by the kidneys. Other organic anions can competitively inhibit the elimination. Probenecid was developed during World War II to "stretch" penicillin (pharmacokinetic booster). However, it came too late in the market to actually be used.

unwanted effects

The most common adverse effects include:

see also

Beta-lactam antibiotics, beta-lactamase inhibitors, rash on amoxicillin

  • Pharmaceutical product information (CH, USA)
  • Pharmacotherapy textbooks
  • Martin W.J. The penicillins. J Lancet, 1967, 87 (3), 79-88 Pubmed
  • Miller E.L. The penicillins: a review and update. J Midwifery Womens Health, 2002, 47 (6), 426-34 Pubmed
  • Nathwani D., Wood M.J. Penicillins. A current review of their clinical pharmacology and therapeutic use. Drugs, 1993, 45 (6), 866-894 Pubmed
  • New H.C. The penicillins. II. Overview of pharmacology, toxicology, and clinical use. NY State J Med, 1977, 77 (6), 962-7 Pubmed
  • Other sources

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on February 15, 2021.
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