Ampicillin: Dosage And Precautions
Ampicillin is an antibiotic drug that belongs to the penicillin family: it is a β-lactam antibiotic. It is the first semi-synthetic penicillin developed.
It was synthesized between 1959 and 1961 by the pharmaceutical laboratory GlaxoSmithKline or GSK. It has been used since 1961 to treat many infections of bacterial origin.
The reason for the development of ampicillin is that the bacteria started to become resistant to penicillin. After this fact, they wanted to discover a drug with a spectrum greater than that.
Thus, ampicillin is, together with amoxicillin, one of the main aminopenicillins that we have available on the market. It is used in the treatment of infections caused by gram +, gram – and anaerobic microorganisms. However, we will see the clinical use of this medication later.
How does ampicillin exert its effect on the body?
It is a bactericidal antibiotic, that is, it is capable of causing the death of the pathogenic microorganism. Its antimicrobial action is due to its ability to inhibit bacterial cell wall synthesis.
The cell wall is a vital structure for bacteria; if they cannot synthesize it, they die. To inhibit the synthesis of this structure, ampicillin blocks the last phase of its formation. Specifically, it binds to proteins known as PBPs or penicillin binding proteins , which are specific to the bacterial cell wall.
By blocking wall synthesis, ampicillin kills the bacteria. However, there are several bacteria that have a resistance mechanism to this type of antibiotic. They have enzymes called beta-lactamases that are able to break down the chemical structure of ampicillin, making it ineffective.
Ampicillin Indications
As we mentioned, ampicillin is used to treat bacterial infections. Specifically, it is indicated to fight diseases triggered by some of the following bacteria:
- Listeria monocytogenes.
- Haemophilus influenzae that do not produce beta-lactamases.
- Neisseria meningitidis.
- Bordetella pertussis.
Ampicillin is therefore used to treat infections caused by microorganisms sensitive to this medication. Some examples are otitis media, sinusitis and cystitis.
Pharmacokinetics: what happens to ampicillin in the body?
Pharmacokinetics includes the processes of absorption, distribution, metabolism and elimination of a drug. In this sense, ampicillin can be administered orally and parenterally, depending on the patient’s needs. Oral absorption is approximately 30-55% of the dose.
Remember that if ampicillin is taken by mouth after food is consumed, absorption will be inhibited. Therefore, this medication should be taken on an empty stomach.
Once absorbed, it requires plasma proteins for distribution, albeit in a very low percentage. It is widely distributed; It is able to cross the blood-brain barrier and is useful in the treatment of meningitis. However, it does not cross the placenta.
Finally, it is metabolized into molecules that have no activity and is mainly eliminated in the urine.
Dosage: what are the recommended doses?
The differentiation must be made depending on its parenteral or oral administration. First, for parenteral administration, the recommended doses are:
- Adults and young people: can be administered intravenously or intramuscularly at a dose between 0.5 and 1 g every 6 hours.
- Children and infants: the administration routes are the same and the dose is reduced to 100/200 mg / kg / day divided into administrations every 4 and 6 hours.
As for oral administration, observe the following recommendations:
- Adults and young people: there are doses between 0.25 and 1 g. It should also be administered every 6 hours. You should never exceed a total dose of 14 g per day.
- Children: the dose is reduced to 50-100 mg / kg / day in equal doses every 6 hours.
However, the instructions given by the physician for each patient and for a specific case must be followed. Antibiotics should never be taken without a prescription.
