Azithromycin is a drug widely used to treat different organs, from the lungs to the gastrointestinal system.
Currently, it is classified by the World Health Organization as an antimicrobial of utmost importance in current medicine.
Azithromycin gained popularity in the media when a group of scientists claimed that the concomitant use of azithromycin and hydroxychloroquine are effective in treating COVID-19.
Throughout the article, we will explain everything you need to know about this much-talked about medication.
What is azithromycin?
Azithromycin is an antimicrobial used to treat a myriad of diseases (as we will see later).
Despite its increasing popularity in the media, azithromycin was discovered in 1980 by a group of researchers in the former Yugoslavia. A year later, it was patented by the company Pliva.
Its international commercialization, especially in the United States and Western Europe, began in 1988.
Since its introduction to the market, it has become a very frequently used antibiotic. Currently, it is the 57th most prescribed drug in the U.S.
What is azithromycin for?
Azithromycin is a broad-spectrum antimicrobial medicine. This means it can be used against a plethora of susceptible bacteria.
The term susceptible refers to those bacteria that are sensitive to certain antibacterials and, therefore, can be eliminated relatively easily.
Azithromycin is particularly useful against a group of bacteria called Gram-positive (those bacteria whose walls stain purple during microscopic studies).
It is also used against Gram negative bacteria (whose wall stains pink).
These two types of bacteria are the most common infectious agents in medical practice.
It is also useful against bacteria that do not have a cell wall (causing a type of pneumonia) and other unusual classes of bacteria.
Composition of azithromycin
Azithromycin is a macrolide and, in turn, a member of the azalide subfamily.
The prototype drug (the drug from which the rest is derived), and the most widely used, is erythromycin. Modifications in the biochemical structure of erythromycin give rise to azalides.
The mechanism of action of macrolides in general is to inhibit protein synthesis by bacteria. Specifically, the blocked proteins play a very important role in cell division.
Macrolides are generally slow-acting bacteriostatics. They do not degrade or destroy the bacteria, they only stop the replication of the bacteria. In this way, the infection is prevented from evolving.
Presentations and dose of azithromycin
Azithromycin is currently marketed as a generic drug. Its most common presentation are tablets, oral suspensions, intravenous injections and even ophthalmic solutions.
Its oral presentation is due to the fact that the medicine is stable in an acidic environment (a very low pH), such as the stomach. It is carried to the intestines, where it is reabsorbed into the circulation and performs its function.
The concentration of the drug in doses each presentation starts from 2.5, 2 and 1 grams. There are also presentations of 600 mg, 500 mg, 250 mg, 200 mg/5 mL and 100 mg/5 mL.
Diseases treated with azithromycin
As we have already explained, macrolides are broad-spectrum antibiotics.
They are effective as a treatment against diseases that affect different organs, starting from the respiratory system (trachea, larynx, bronchi and lungs), going through skin infections to the genital system.
Bronchitis
Lower respiratory tract infections that affect the bronchi can be treated with azithromycin.
Not all cases of acute bronchitis require antibiotic treatment, but if necessary, azithromycin is part of the first line of options that are administered to the patient.
Its effectiveness lies in its anti-inflammatory properties, which manage to reduce the release of pro-inflammatory molecules or free radicals that cause tissue injury.
Bronchitis is generally caused by gram-negative bacteria such as Bordetella pertussis, which causes whooping cough, or other types of bacteria, such as Chlamydia pneumoniae and Mycoplasma pneumoniae.
Studies have shown that even low concentrations of azithromycin are capable of inhibiting the action of these last two microorganisms.
Pneumonia
Lung infection can be caused by a large number of different bacteria.
Patients suffering from chronic obstructive pulmonary disease (COPD) are more prone to pneumonia due to loss of airway defenses.
Among the most common causative agents to cause pneumonia we find Streptococcus Pneumoniae and Haemophilus Influenzae. The drug has been shown to be highly effective against these.
However, within the same species of bacteria treated with azithromycin, there are strains resistant to it because they have developed defense mechanisms. They are known as resistant strains.
Over the years, there has been an increase in the number of said strains. Despite this, azithromycin continues to be a widely used antibiotic to treat most cases.
A study published in the Respiratory Medicine Journal showed that the use of azithromycin reduced the rate of hospitalizations caused by pneumonia or any complications caused by it.
Sexually transmitted diseases
There are a plethora of sexually transmitted diseases (STDs) that can be treated using azithromycin, such as syphilis, genital ulcers (chancre), urethritis, and gonococcal and non-gonococcal cervicitis.
A study published by the Department of Microbiology at the University of Iceland where the efficacy of azithromycin was compared against doxycycline in 168 patients. Of these, 113 were given azithromycin for four weeks.
More than 90% of the patients with gonorrhea or chlamydia demonstrated very favorable results, again demonstrating the effectiveness of this drug.
ear infections
Otitis media is generally caused by Haemophilus Influenzae, Moraxella Catarrhalis, or Streptococcus Pneumoniae; all microorganisms that fight azithromycin.
However, azithromycin is not the first choice against acute ear infections. It’s amoxicillin. However, in patients who are allergic to the latter, the use of azithromycin is employed.
nasal infections
The inside of our nose is covered with a mucous layer, whose function, among many others, is to trap inhaled foreign substances. When there is a bacterial infection at this level, inflammation is generated.
In most cases, the culprit is a virus. However, they can also be caused by bacteria.
When there is a persistent infection of intermediate severity, certain antibiotics, such as amoxicillin, are used.
throat infections
Pharyngitis (inflammation of the pharynx or throat) can be caused by streptococcal bacteria. Generally, beta-lactams are used against these and not azithromycin.
The latter is used in case of allergies to the former. However, azithromycin offers a certain advantage because it fights a greater number of bacteria and can eliminate those that are particularly resistant.
skin infections
Our skin is home to multitudes of bacteria that act as a barrier by creating a toxic environment for most invading microorganisms.
However, when there is a break in the skin, benign bacteria become infectious by entering the skin and causing infections. In uncomplicated skin infections, azithromycin has been shown to be effective and safe for the person.
A study published in the Journal of Antimicrobial Chemotherapy showed that the drug eradicated approximately 90% of the agents that cause skin infections.
gastrointestinal infections
Azithromycin is the treatment of choice to treat enteritis caused by Campylobacter.
Other types of infections such as typhoid fever or enteritis caused by Shigella specimens are usually treated with other antibiotics.
However, comparative studies have shown that azithromycin offers similar benefits to other antibiotics (eg, ciprofloxacin) in treating these conditions.
Azithromycin is also administered as a safety measure for those patients who require colorectal surgery, thus avoiding possible infections.
contraindications of azithromycin
Current global recommendations indicate that administering azithromycin to pregnant patients requires careful consideration. Only if the possible benefits outweigh the possible risks, azithromycin is given.
No complications derived from its administration in pregnant patients have been detected. However, the medical community cautions against continued study of the drug.
Azithromycin can reach significant levels of accumulation in breast milk (up to 50%).
As in the previous point, there is not enough medical evidence to dictate a positive or negative statement about its use during lactation.
Despite this, azithromycin is currently contraindicated in pregnant and lactating women.
Azithromycin Precautions
Patients with pre-existing cardiovascular problems, are under treatment to treat arrhythmias, or low levels of potassium and magnesium in the blood are at increased risk of developing adverse cardiac effects.
The main reason is the disturbance of the electrical activity of the heart due to the effect of the macrolide, generating irregular activities and, subsequently, arrhythmias and heart failure.
Another precaution is the indiscriminate administration of the drug for infections that do not require it, which leads to a loss of its effectiveness since the microorganism develops defense mechanisms against azithromycin.
Therefore, international recommendations place azithromycin as a drug used only for certain cases that warrant it.
Azithromycin Side Effects
Adverse effects have been reported from the administration of this medicine. However, these unwanted effects are rare, most only occurring in 0.7% of cases. Others, on the other hand, are more common.
Gastrointestinal disorders
Gastrointestinal disturbances are the most observed adverse effects. Among these, we have: diarrhea, nausea, vomiting and abdominal pain.
A study published by the International Journal of Antimicrobial Agents showed that, in patients with chronic bronchitis treated with azithromycin, they presented adverse symptoms in at least 18.3% of the cases.
In certain cases, a hepatotoxicity reaction due to damage to the liver, effect of azithromycin, has also been reported.
Nervous system disorders
Neurological alterations are less common than the previous ones, but cases have been reported where the person develops nervousness and even delirium. However, these cases occurred mainly in elderly patients.
Cases have been reported where patients, who were administered azithromycin, developed moderate to severe deafness due to neuronal and sensitive involvement at the level of the inner ear.
allergic skin reactions
Hypersensitivity reactions are possible complications or adverse reactions.
Among these, we find the appearance of an exanthema (rash), fever, pruritus (itching sensation) and eosinophilia.
The latter is a parameter used by laboratories to determine if an allergic reaction to the drug has occurred.
Fatigue
Fatigue has been another observable side effect in experimental clinical studies in adults.
In this case, fatigue is not a direct effect of the biochemical actions of the drug. It is secondary to the appearance of alterations in other body systems, such as hematological alterations or damage to the liver.
Vertigo
In the elderly population, or those with some kind of renal or hepatic insufficiency, accumulation of azithromycin in the blood may occur. By extension, it accumulates in greater amounts in the tissues.
Certain tissues, such as the liver, usually, and the inner parts of the ear. The affectation of the latter by the effect of a drug is called ototoxicity.
As the inner ear is involved in the coordination of movements, posture and balance, its disturbances lead to symptoms such as tinnitus and vertigo.
Visual disturbances
Certain bacteria can affect the eyeball, such as Chlamydia Trachomatis. To treat them, azithromycin is administered in its oral presentation or in eye drops.
As an adverse response to the drug, irritation of the eyeball, disproportionate sensitivity to light (photosensitivity), burning sensation, and even blurred vision may occur.
University Professional in the area of Human Resources, Postgraduate in Occupational Health and Hygiene of the Work Environment, 14 years of experience in the area of health. Interested in topics of Psychology, Occupational Health, and General Medicine.