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Structural formula
Structural formula of ampicillin
Non-proprietary name Ampicillin
other names

(2 S , 5 R , 6 R ) -6- (2-Amino-2-phenyl-acetyl) amino-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane 2-carboxylic acid ( IUPAC )

Molecular formula
  • C 16 H 19 N 3 O 4 S (ampicillin)
  • C 16 H 18 N 3 NaO 4 S
External identifiers / databases
CAS number
  • 69-53-4 (ampicillin)
  • 69-52-3 (ampicillin sodium salt )
EC number 200-709-7
ECHA InfoCard 100,000,645
PubChem 6249
ChemSpider 6013
DrugBank DB00415
Wikidata Q244150
Drug information
ATC code
Drug class


Molar mass 349.41 g · mol -1
Physical state


Melting point

199–202 ° C (decomposition)


slightly soluble in water

safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS labeling of hazardous substances
07 - Warning 08 - Dangerous to health


H and P phrases H: 315-317-319-334-335
P: 261-280-305 + 351 + 338-342 + 311
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Ampicillin is a semi-synthetic, antibiotic active substance from the group of β-lactam antibiotics ( aminopenicillins ). Because of its effectiveness against gram-positive pathogens (as well as some gram-negative rods), it is classified as a broad spectrum antibiotic or broad spectrum penicillin.

Chemically, ampicillin is one of the aminopenicillins and was first synthesized by John C. Sheehan .


application areas

Broad-spectrum penicillins are used for infections of all kinds against which "conventional" penicillins are ineffective. These include u. a. certain infections of the gastrointestinal tract, respiratory tract, middle ear, biliary tract and urinary tract. In particular, they are suitable for treating infections with gram-negative rods, which have a natural resistance to standard penicillins.

Mechanism of action

The bacteriolytic effect of ampicillin sets in after bacteria have divided. As with all β-lactam antibiotics, it is based on blocking the enzyme D-alanine transpeptidase, which is necessary for the formation of a new murein layer . Ampicillin prevents the new synthesis of a stable cell wall. The division of human cells is not hindered because human cells do not contain a murein layer.

The β-lactam antibiotic ampicillin not only blocks the division of bacteria, including cyanobacteria , but also the division of cyanelles, the photosynthetically active organelles of the Glaucocystaceae , and the chloroplasts of bladder moss , liverworts ( Marchantia polymorpha ) and moss ferns ( Selaginella nipponica ) . However , they have no effect on the division of the plastids in more highly developed vascular plants such as tomatoes . This is an indication that in higher plants due to evolutionary changes in plastid division, β-lactam antibiotics generally no longer have any effect on chloroplasts.

Tolerability, side effects

Ampicillin is over other broadband penicillins, such as amoxicillin at peroral intake worse tolerated because it is relatively poorly absorbed from the intestine. As a result, a high proportion of the active ingredient remains in the intestine and damages the digestive microbial colonization ( intestinal flora ) there. With ampicillin, gastrointestinal complaints are very common. Side effects include diarrhea, nausea and vomiting. A very rare effect, however, is the cause of pseudomembranous colitis .

One of the most common skin reactions is hives .

Like all penicillins, ampicillin can also often trigger an allergy , which can lead to anaphylactic shock (which occurs very rarely) . Often - and not to be confused with an allergy - is also a measles- like drug eruption (a rash called "ampicillin rash"), which can occur 7 to 10 days after the first dose, even if the drug has already been discontinued. This non-urticarial rash is particularly common and pronounced in connection with infectious mononucleosis . The occurrence of this rash does not speak against the subsequent use of penicillin or its derivatives (such as ampicillin).

Occasionally there may be an increase in transaminases.

Headache, dizziness, changes in the blood count ( eosinophilia , neutropenia , anemia ), inflammatory reaction of the blood vessels ( vasculitis ), interstitial nephritis (inflammation of the kidneys) and laryngeal edema affecting the airways have been reported rarely to very rarely .

Interactions with other means

In the case of oral contraceptives (contraceptives in tablet form; "pill"), influencing the intestinal flora can lead to a reduced absorption of the contraceptive in the blood and thus to a reduced effectiveness.

For theoretical considerations, there is a requirement that bacteriostatic antibiotics should not be combined with penicillins as they limit their effectiveness. The reason for this is seen in the fact that penicillins intervene in the division phase of the bacteria and thus find no point of attack if division is prevented by bacteriostatic means. This turns out to be irrelevant in actual use, the combination of ampicillin and other penicillins z. B. with the bacteriostatically effective macrolides is a tested and established standard therapy z. B. from pneumonia .

Indomethacin , phenylbutazone , probenecid , salicylates and sulfinpyrazone lead to a prolonged and increased concentration of penicillins in the blood and should therefore not be taken together with penicillins.


Penicillin allergy, hypersensitivity to the active ingredient ampicillin.


Due to the primary amino group, ampicillin, unlike benzyl penicillin (penicillin G), is also effective after oral intake. Ampicillin is taken orally or parenterally several times a day over a period of several days.

Molecular biology

Ampicillin is one of the most widely used selection agents in molecular biology . It is in the transformation of vectors the bacterial cells in culture medium added, in which the cells are to be increased. Only those cells can survive which, during transformation, have taken up the vector that carries ampicillin resistance. To such transgenic E. coli bacteria in z. B. To selectively cultivate LB medium, a final concentration of up to 0.2 mg / ml medium is used. Other antibiotics such as B. Kanamycin or tetracyclines are used for selection media.


It can be synthesized from 6-aminopenicillanic acid .

Trade names


Standacillin (A), generics (D)

Combination preparations (ampicillin / sulbactam)

Unasyn (A), Unacid (D), Generics + Sulbactam (D, A)

Veterinary medicine

Ampiciph, Ampisan, Ampitab, Aniclox, Apicin, Frommcillin, Gelstamp, Mastipent, Totocillin

Web links

  • Vetpharm entry for ampicillin , accessed August 4, 2012.

Individual evidence

  1. ^ A b The Merck Index : An Encyclopedia of Chemicals, Drugs, and Biologicals , 14th Edition (Merck & Co., Inc.), Whitehouse Station, NJ, USA, 2006; ISBN 978-0-911910-00-1 .
  2. a b Datasheet Ampicillin trihydrate from Sigma-Aldrich , accessed on October 20, 2016 ( PDF ).
  3. ↑ Technical information Ampicillin-ratiopharm (summary of product characteristics) from ratiopharm GmbH - as of July 2007.
  4. a b Kasten, Britta and Reski, Ralf (1997): β-Lactam antibiotics inhibit chloroplast division in a moss (Physcomitrella patens) but not in tomato (Lycopersicon esculentum). In: Journal of Plant Physiology. 150, 1997, pp. 137-140, doi : 10.1016 / S0176-1617 (97) 80193-9 .
  5. Tounou, E. et al . (2002): Ampicillin Inhibits Chloroplast Division in Cultured Cells of the Liverwort Marchantia polymorpha . In: Cytologia 67 ; 429-434; doi : 10.1508 / cytologia.67.429 .
  6. Izumi, Y. et al . (2003): Inhibition of plastid division by ampicillin in the pteridophyte Selaginella nipponica Fr. et Sav. In: Plant Cell Physiol . 44 (2); 183-189; PMID 12610221 ; PDF (free full text access).
  7. ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 338.
  8. Marianne Abele-Horn (2009), p. 338.
  9. Marianne Abele-Horn (2009), p. 338.
  10. Marianne Abele-Horn (2009), p. 338.
  11. Guideline "Pneumonia, Community Acquired, Treatment and Prevention of Adult Patients" of the German Society for Pneumology and Respiratory Medicine , version dated February 25, 2016.