Azithromycin is an antibiotic belonging to the class of macrolides. It is a semisynthetic derivative of erythromycin, the progenitor of this family.
Azithromycin - Chemical Structure
Compared to its precursor erythromycin, azithromycin has greater stability in an acid environment, a greater plasma half-life and also a broader spectrum of action.
Often, when macrolide therapy is required, azithromycin is the first choice antibiotic.
Indications
For what it uses
Azithromycin is used to treat bacterial infections caused by microorganisms sensitive to it.
More precisely, azithromycin is indicated for the treatment of:
- Upper and lower respiratory tract infections, such as sinusitis, middle ear infections, tonsillitis, pharyngitis, bronchitis and pneumonia;
- Odontostomatological infections;
- Skin and soft tissue infections;
- Non-gonococcal urethritis caused by Chlamydia trachomatis ;
- Cervical infections sustained by chlamydia;
- Soft ulcer caused by Haemophilus ducreyi infections.
Warnings
Caution should be exercised when administering azithromycin to patients with severe renal impairment.
Azithromycin is mainly metabolized in the liver, therefore, the administration of the drug in patients suffering from liver disease must be carried out with caution and under the strict control of the doctor.
In the event of hepatic dysfunction, azithromycin treatment should be discontinued immediately.
Azithromycin therapy can promote the onset of superinfections with resistant bacteria or fungi that normally populate the human bacterial flora, such as, for example, Clostridium difficile or Candida albicans .
Clostridium difficile is considered to be responsible for the onset of pseudomembranous colitis, characterized by the appearance of severe diarrhea. Colitis can sometimes be fatal and can appear even months after the treatment with the antibiotic is completed.
Azithromycin may cause a prolongation of the QT interval (the interval of time required by the ventricular myocardium to depolarize and repolarize), with an increased risk of cardiac arrest. Therefore, great caution should be used when administering the drug to patients with pre-existing cardiac conditions.
Azithromycin may worsen the symptoms of pre-existing patients with myasthenia gravis (a neuromuscular disease).
In the event of any type of allergic reaction, treatment with azithromycin should be stopped immediately and adequate therapy should be started.
Interactions
It is not advisable to take azithromycin and antacid drugs at the same time, as the plasma concentration of azithromycin can be reduced.
Azithromycin may increase the plasma concentration of digoxin (a drug used to increase the strength of cardiac contraction), therefore, caution should be used.
Concomitant intake of azithromycin and ergotamine (a drug used in the treatment of migraine) or its derivatives is not recommended due to the possible onset of ergotism.
In patients already on statin therapy (drugs used to treat hypercholesterolemia) azithromycin can cause rhabdomyolysis, which is the rupture of the cells that make up the skeletal muscles with consequent release into the bloodstream of the substances contained in the musculature.
Azithromycin could potentiate the activity of cumarinic oral anticoagulants (such as warfarin ), so - in case of concomitant administration - more frequent prothrombin time checks should be performed.
Azithromycin can increase the plasma concentration of cyclosporine (an immunosuppressive drug used in the prevention of rejection in transplants), therefore - if co-administration of the two drugs is necessary - it is essential to pay close attention and regularly monitor the blood concentration of ciclosporin.
Nelfinavir (an antiviral drug) may increase the plasma concentration of azithromycin.
Azithromycin could increase the effect of theophylline (used in the treatment of bronchial asthma), alfentanil (an opioid drug) and astemizole (an antihistamine drug).
Concomitant use of azithromycin and cisapride can cause cardiovascular disorders.
In any case, it is necessary to inform your doctor if you are taking - or have recently been taken - drugs of any kind, including over-the-counter medicines and herbal and / or homeopathic products.
Side effects
Azithromycin can cause various side effects, although not all patients experience them. Since each person has his own sensitivity to the drug, it is not said that the adverse effects occur all with the same intensity in each individual.
Below are the main side effects that can occur during azithromycin therapy.
Blood and lymphatic system disorders
Treatment with azithromycin can cause disorders of the blood and lymphatic system (ie the system used to produce blood cells). 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 bleeding;
- Leukopenia, ie the reduction in the number of leukocytes in the bloodstream;
- Eosinophilia, ie an increase in the blood concentration of eosinophils.
Superinfections
Treatment with azithromycin can promote the development of infections from resistant bacteria and fungi that are normally part of the human bacterial flora. These superinfections include:
- Clostridium difficile infections that can cause pseudomembranous colitis;
- Oral (thrush) and vaginal candidiasis;
- Vaginal infections;
- Pneumonia and respiratory disorders;
- Gastroenteritis.
Allergic reactions
Azithromycin can cause allergic reactions in sensitive individuals. These reactions can occur in the form of angioedema or anaphylactic reactions.
Nervous system disorders
Azithromycin therapy can cause:
- Headache;
- Drowsiness;
- dizziness;
- paresthesia;
- Hypoaesthesia;
- Loss of sense of taste;
- Psychomotor hyperactivity;
- Convulsions;
- Syncope.
Psychiatric disorders
Azithromycin treatment can induce:
- Insomnia;
- Nervousness;
- agitation;
- Anxiety;
- Hallucinations;
- Delusions;
- Aggression.
Ear and labyrinth disorders
Azithromycin therapy can cause hearing disorders, dizziness and deafness.
Cardiovascular disorders
Treatment with azithromycin can cause various problems with the cardiovascular system, including:
- Hot flashes;
- Hypotension;
- Palpitations;
- QT interval extension;
- Peak twists;
- Ventricular tachycardia;
- Arrhythmias.
Gastrointestinal disorders
Azithromycin therapy can cause:
- Nausea and vomit;
- Diarrhea;
- Abdominal pains;
- Constipation;
- Flatulence;
- Dyspepsia;
- Dysphagia;
- gastritis;
- Abdominal distension;
- Belching;
- Pancreatitis.
Furthermore, the drug can cause dry mouth, mouth ulcers and discoloration of the tongue.
Hepatobiliary disorders
Azithromycin can cause changes in liver function, liver failure, hepatitis and cholestatic jaundice.
Skin and subcutaneous tissue disorders
Treatment with azithromycin may promote the onset of:
- Skin eruptions;
- Urticaria;
- Itch;
- Dermatitis;
- Skin dryness;
- Photosensitivity reactions;
- Hyperhidrosis;
- Stevens-Johnson syndrome;
- Toxic epidermal necrolysis;
- Erythema multiforme.
Kidney and urinary tract disorders
Azithromycin therapy can cause kidney pain and dysuria (difficulty urinating). Furthermore, the drug could favor the onset of acute renal failure and interstitial nephritis.
Other side effects
Other side effects that may occur during azithromycin treatment are:
- Asthenia;
- Temperature;
- Edema;
- Anorexia;
- Changes in vision;
- Myasthenia gravis;
- arthralgia;
- Myalgia;
- Osteoarthritis;
- Dyspnoea;
- Epistaxis.
Overdose
The symptoms that can occur if you take an azithromycin overdose are:
- Malaise;
- Severe nausea;
- He retched;
- Diarrhea;
- Temporary deafness.
If you suspect an overdose of azithromycin, you must inform your doctor immediately and contact the nearest hospital.
Action mechanism
Azithromycin is a macrolide and, as such, exerts its antibiotic action by interfering with the protein synthesis of bacteria.
Protein synthesis in bacterial cells takes place thanks to organelles called ribosomes.
Ribosomes consist of ribosomal RNA and proteins associated with each other to form two subunits:
- The 30S subunit, consisting of 21 proteins and one RNA molecule (16S);
- The 50S subunit, consisting of 34 proteins and two RNA molecules (23S and 5S).
These organelles bind and translate the messenger RNA that comes from the cell nucleus, thus synthesizing the proteins for which it encodes.
Azithromycin binds to the 23S ribosomal RNA molecule present within the 50S subunit.
The azithromycin-RNA binding prevents the RNA itself from completing protein synthesis, thereby inhibiting bacterial cell growth.
Mode of Use - Posology
Azithromycin is available for oral administration in the form of tablets and powder for oral suspension.
The tablets should be swallowed whole, without chewing.
The drug can be taken either on an empty stomach or after a meal.
Food intake before azithromycin administration can reduce any gastrointestinal side effects that may occur.
Following are some indications on the doses of azithromycin usually used.
Adults
In adults, the dose of azithromycin usually administered is 500 mg of drug per day, in a single administration and for three consecutive days.
For Chlamydia trachomatis and Haemophilus ducreyi infections, the usual dose of medication is 1 g per day in a single oral administration.
children
For children with body weight equal to or greater than 45 kg, the dose of azithromycin usually used is the same used for adults, ie, 500 mg of drug per day, for three consecutive days.
In any case, the maximum dose of azithromycin that can be used in any type of pediatric therapy is 1500 mg of drug.
Senior citizens
Even in elderly patients the same doses of azithromycin used in adults can be used, except in the case where such patients are at risk of developing cardiac arrhythmias. In this case, caution is advised.
Pregnancy and breastfeeding
It cannot be excluded that azithromycin is capable of causing damage to the fetus and / or the newborn. Therefore, the use of the drug by pregnant women should be done only in cases of absolute necessity, only under the strict supervision of the doctor and only after a careful evaluation of the relationship between the expected benefit for the mother and the potential risk for the fetus or the newborn.
Since azithromycin is excreted in breast milk, the use of the drug by breastfeeding mothers should be avoided. If taking azithromycin is essential, mothers should stop breastfeeding.
However, pregnant women and breastfeeding mothers should always seek medical advice before taking any medication.
Contraindications
The use of azithromycin is contraindicated in patients with known hypersensitivity to azithromycin itself, to erythromycin, to other macrolides or to ketolides.
