Drug Characteristics and Clinical Application of Ampicillin

Ampicillin  is a semi-synthetic broad-spectrum penicillin, which is a β-lactam antibiotic that can treat a variety of bacterial infections common in veterinary clinics. Mainly used for Escherichia coli, Salmonella, Pasteurella, Shigella, Streptococcus, Enterococcus and other respiratory system, reproductive system, digestive system infection.

Physical and chemical properties

Ampicillin is slightly soluble in water, insoluble in chloroform, ethanol, ether or fixed oil; soluble in dilute acid solution or dilute alkali solution, but unstable in water and strong acid-base solution. Therefore, the stability and drug dissolution of veterinary oral preparations determine one of the key technical indicators for its efficacy.

Therefore, in animal clinics, ampicillin preparations usually include soluble powders, injections, powder injections, tablets, and the like. For poultry medicine, soluble powder is the most economical and convenient dosage form; for cattle, sheep, pigs and other large animals, injection and powder injection are the most commonly used dosage forms.

pharmacological action

The antibacterial mechanism of ampicillin is mainly by acting on the cell wall of bacteria, inhibiting and preventing the synthesis of bacterial cell wall, so it can not only inhibit its proliferation, but also directly kill various sensitive bacteria. It works best on all reproductive stages of sensitive bacteria.

Its anti-gram-positive bacteria effect is similar to that of penicillin, especially for Streptococcus viridans and Enterococcus, but it is poor for other Gram-positive bacteria, especially for penicillin-resistant Staphylococcus aureus.

In the spectrum of action against Gram-negative bacteria, it is sensitive to Escherichia coli, Typhoid and Paratyphoid Bacillus, Shigella, Proteus mirabilis, Influenza Bacillus, etc., but is prone to drug resistance.


Oral preparations of ampicillin are easily absorbed after oral administration or injection, and can be distributed into various tissues after absorption. It can reach antibacterial concentrations in blood, urine and bile, and can penetrate into human cerebrospinal fluid and synovial fluid, but the content is low. The amount of penetration can be significantly increased when there is inflammation.

Ampicillin is mainly excreted in urine and bile. Within 24 hours after oral administration, 15% of the dose was excreted from the urine; about 56% of the dose was excreted within 24 hours after intramuscular injection; 70% of the dose was excreted within 24 hours after intravenous injection. The vast majority of the excretion of various routes of administration were excreted within the first 6 hours.


Oral use: one dose, per kilogram body weight, 30-60 mg for livestock and poultry, 2-3 times/d; 20-40 mg for dogs and cats, 2-3 times/day, for 3 days.

Intramuscular or intravenous injection: one dose, per kilogram body weight, 10-20 mg for livestock, poultry, dogs, and cats, 2-3 times/d, for 2-3 days, for 3 days.

Inject into the milk duct, one dose, per milk room, 200 mg for cows, once/d.

drug compatibility

It cannot be used in combination with macrolides, tetracyclines, amide alcohols, lincosamides and other reproductive period bacteriostatic agents, otherwise, the interaction between the two will be weakened after compatibility.

When ampicillin is used in combination with sulfa drugs and some antipyretic and analgesic drugs (such as analgin, carbaspirin calcium), these drugs can reduce the excretion of ampicillin, so it will increase its blood concentration .

Ampicillin cannot be mixed with calcium, vitamin B group, vitamin C, amino acid and other preparations for compatibility use, otherwise it will reduce its drug bioavailability or promote the degradation and effect of ampicillin.


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