Benzylpenicillin (formerly known as penicillin G) is a β-lactam antibiotic used in the treatment of many types of infections.
Benzylpenicillin was one of the first natural penicillins to be discovered and is still used today in therapy.
Indications
For what it uses
Benzilpenicillin - Chemical Structure
Benzylpenicillin is indicated for the treatment of infections caused by bacteria sensitive to the benzylpenicillin itself.
In particular, the drug is very useful in the treatment of infections of the airways and in infections of the genito-urinary tract.
Warnings
Before taking benzylpenicillin it is necessary to have excluded any hypersensitivity to other types of penicillins or to cephalosporins (other β-lactam antibiotic drugs).
In the event of allergic reactions, treatment with benzylpenicillin should be stopped immediately.
In patients with renal insufficiency, benzylpenicillin excretion is slowed. Furthermore, the use of the drug at high doses in this category of patients may favor the onset of metabolic encephalopathies with consequent disturbances of consciousness, abnormal movements and convulsive crises.
Caution should be used when administering penicillin in patients with a history of asthma.
During long-term treatment with benzylpenicillin - especially at high doses - renal and hematopoietic function should be regularly monitored and electrolyte levels should also be monitored.
In any case, the renal and cardiovascular functions of the patients must, however, be regularly checked. If there are abnormalities of the aforementioned functions, a reduction in the usual dose of benzylpenicillin may be necessary.
Prolonged use of benzylpenicillin can cause superinfections with non-sensitive germs and fungi (such as, for example, Candida albicans infections). Such superinfections require adequate drug treatment.
Interactions
The concomitant administration of benzylpenicillin and antibiotics with bacteriostatic action (ie able to inhibit bacterial growth) may decrease the bactericidal effect (ie able to kill bacteria) of benzylpenicillin, since it slows the rate of bacterial growth.
Concomitant use of benzylpenicillin and probenecid (a drug used in the treatment of hyperuricemia and gout) causes an increase in the plasma concentration of benzylpenicillin itself.
However, you need to tell your doctor if you are taking - or if you have recently been - drugs of any kind, including non-prescription drugs and herbal and / or homeopathic products.
Side effects
Benzylpenicillin can cause various side effects, although not all patients experience them. This depends on the different sensitivity that each patient has towards the drug. Therefore, it is not said that the undesirable effects are all manifested with the same intensity in each individual.
The following are the main adverse effects that may occur during benzylpenicillin therapy.
Allergic reactions
Benzylpenicillin can trigger allergic reactions in sensitive individuals. These reactions can occur in the form of:
- Maculopapular skin eruptions;
- Urticaria;
- Chills;
- Temperature;
- Edema;
- arthralgia;
- Anaphylaxis, sometimes with fatal results.
Blood and lymphatic system disorders
Treatment with benzylpenicillin can cause disorders of the system responsible for the production of blood cells (hemolymphopoietic system). Such disturbances can cause:
- Hemolytic anemia;
- Plateletopenia (ie the decrease in the number of platelets in the bloodstream), with a consequent increase in the risk of abnormal bleeding and / or bleeding;
- Leukopenia (ie the reduction in the number of leukocytes in the bloodstream), with consequent increased susceptibility to the contraction of new infections.
However, these types of side effects are rare and appear mainly following intravenous administration of benzylpenicillin.
Nervous system disorders
Benzylpenicillin therapy can cause hyperreflexia, convulsions and / or coma.
Kidney and urinary tract disorders
Treatment with benzylpenicillin can cause kidney disease and renal failure.
Other side effects
Other side effects that may occur during treatment with benzylpenicillin are:
- Neuropathy;
- Potassium intoxication which is sometimes lethal;
- Jarisch-Herxheimer reaction, a reaction that occurs when large amounts of toxins are released into the body resulting from the killing of the bacteria by the benzylpenicillin itself.
Overdose
In the case of benzylpenicillin overdose, neurological adverse reactions may occur and high amounts of the drug may be present in the cerebrospinal fluid.
There is no real antidote for the treatment of benzylpenicillin overdoses, therefore, the treatment is purely symptomatic and supportive. However, hemodialysis can be useful.
In any case, if you suspect you have taken an overdose of medication, you must immediately inform your doctor or contact your nearest hospital.
Action mechanism
Benzylpenicillin interferes with the synthesis of peptidoglycan, ie with the synthesis of the bacterial cell wall.
Peptidoglycan is a polymer consisting of two parallel chains of nitrogenated carbohydrates, joined together by transverse bonds between amino acid residues. These bonds are formed thanks to the action of a particular enzyme, transammidase.
Benzylpenicillin - as, indeed, all penicillins - binds to transammidase preventing it from performing its action. In doing so, weak areas are created inside the peptidoglycan at the points where the transamidase has not catalyzed the formation of the aforementioned transverse bonds. These weak points lead to the lysis of the bacterial cell and, finally, to its death.
Mode of Use - Posology
Benzylpenicillin is available for intramuscular or intravenous infusion. It is in the form of a powder for solution for injection which must be dissolved in a suitable solvent just before its administration.
The dosage of benzylpenicillin must be established by the doctor.
Generally, the dose of drug used in adults is 1-2 million units in doses refracted over 24 hours. In children, on the other hand, lower dosages are used.
Pregnancy and breastfeeding
The use of benzylpenicillin in pregnant women and breast-feeding mothers should only be done in cases of real need and only under the strict supervision of the doctor.
Benzylpenicillin is able to cross the placenta and is excreted in small amounts in breast milk, therefore, caution should be used.
In any case, pregnant women and breastfeeding mothers, before taking benzylpenicillin - or any other medication - must first seek medical advice.
Contraindications
The use of benzylpenicillin is contraindicated in patients with known hypersensitivity to benzylpenicillin itself, to other penicillins or to cephalosporins.
