Full Prescribing Info
Azithromycin monohydrate.
Each film-coated tablet contains: Azithromycin (as monohydrate) 500 mg.
Azithromycin is a nitrogen-containing macrolide or azalide with actions and uses similar to those of erythromycin. It is used in the treatment of a wide variety of infections caused by susceptible organisms.
Pharmacology: Pharmacokinetics: Following oral administration about 40% of a dose of Azithromycin is bioavailable. Absorption from the capsule formulation, but not the tablet formulation, is reduced by food. Peak plasma concentrations are achieved 2 to 3 hours after a dose, but Azithromycin is extensively distributed to the tissues, and tissue concentrations subsequently remain much higher than those in the blood; in contrast to most other antibacterials, plasma concentrations are therefore of little value as a guide to efficacy. High concentrations are taken up into white blood cells. There is little diffusion into the CSF when the meninges are not inflamed. Small amounts of azithromycin are demethylated in the liver, and it is excreted in bile as unchanged drug and metabolites. About 6% of an oral dose (representing about 20% of the amount in the systemic circulation) is excreted in the urine. The terminal elimination half-life is probably in excess of 40 hours.
Microbiology: Antimicrobial Action: Azithromycin has the same antimicrobial actions as erythromycin, only, azithromycin is less active than erythromycin against streptococci and staphylococci, but has greater activity than erythromycin in vitro against some Gram-negative pathogens such as Haemophilus influenzae and Moraxella catarrhalis (Branhamella catarrhalis), as well as having activity against some of the Enterobacteriaceae such as Escherichia coli and Salmonella and Shigella spp. Azithromycin is also more active than erythromycin against Chlamydia trachomatis and some opportunistic Mycobacteria, including Mycobacterium avium complex. It has activity against the protozoa Toxoplasma gondii and Plasmodium falciparum.
Used in situations where microorganisms sensitive to azithromycin have caused the following: Upper respiratory tract infections, sinusitis, pharyngitis, tonsillitis; Acute otitis media; Acute exacerbation of chronic bronchitis, mild to moderately severe community acquired pneumonia; Skin & soft tissue infection; Uncomplicated Chlamydia trachomatis, urethritis & cervicitis.
Dosage/Direction for Use
The usual adult dose of 500 mg is a daily single dose for 3 days. Alternatively, an initial dose of 500 mg may be followed by 250 mg daily for a further 4 days or as prescribed by the physician.
Patients with a history of allergic or hypersensitivity reactions to azithromycin, erythromycin or any of the macrolide antibiotics.
Special Precautions
Azithromycin should not be used in patients with hepatic impairment.
As with erythromycin and other macrolides, rare serious allergic reactions including angioedema and anaphylaxis (rarely fatal), have been reported. Some of these reactions with azithromycin monohydrate have resulted in recurrent symptoms and required a longer period of observation and treatment.
Since liver is the principal route of elimination for azithromycin monohydrate, the use of azithromycin monohydrate should be undertaken with caution in patients with significant hepatic disease. Cases of fulminant hepatitis potentially leading to life-threatening liver failure have been reported with azithromycin monohydrate. Liver function tests/investigations should be performed in cases where signs and symptoms of liver dysfunction occur such as rapid developing asthenia associated with jaundice, dark urine, bleeding tendency or hepatic encephalopathy.
In patients receiving ergot derivatives, ergotism has been precipitated by co-administration of some macrolide antibiotics. There are no data concerning the possibility of an interaction between ergot and azithromycin monohydrate. However, because of the theoretical possibility of ergotism, azithromycin and ergot derivatives should not be co-administered.
As with any antibiotic preparation, observation for signs of superinfection with non-susceptible organisms, including fungi is recommended.
Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including azithromycin monohydrate, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.
C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.
In patients with severe renal impairment (CFR <10 ml/ min) a 33% increase in systemic exposure to azithromycin monohydrate was observed.
Prolonged cardiac repolarization and QT interval, imparting a risk of developing cardiac arrhythmia and torsades de pointes, have been seen in treatment with other macrolides. A similar effect with azithromycin monohydrate cannot be completely ruled out in patients at increased risk for prolonged cardiac repolarization, therefore cautions is required when treating patients: With congenital or documented QT prolongation.
Currently receiving treatment with other active substances known to prolong QT interval such as antiarrhythmics of class IA and III; cisapride and terfenadine.
With electrolyte disturbance, particularly in cases of hypokalemia and hypomagnesemia.
With clinically relevant bradycardia, cardiac arrhythmia or severe cardiac insufficiency.
Exacerbations of the symptoms of myasthenia gravis and new onset of myasthenia syndrome have been reported in patients receiving azithromycin monohydrate therapy.
Safety and efficacy for the prevention or treatment of MAC (Mycobacterium Avium Complex) in children have not been established.
Patients with rare hereditary problems of galactose intolerance, the Lapp lactose deficiency or glucose-galactose malabsorption should not take this medicine.
Adverse Reactions
The most common adverse effects with azithromycin are gastrointestinal disturbances but are usually mild and less frequent than with erythromycin. Transient elevations of liver enzyme values have been reported and, rarely, cholestatic jaundice. Rashes, headache and dizziness may occur. Severe hypersensitivity reactions occur rarely but may be prolonged. Transient alterations in neutrophil counts have been seen in patients receiving azithromycin.
Drug Interactions
Antacid, Carbamazepine, Cimetidine, Terfenadine, Zidovudine, Didanosine, Cyclosporin, Digoxin, Methylprednisolone, Coumarin-type oral Anticoagulants, Rifabutin, Efavirenz, Fluconazole, Indinavir, Nelfinavir, Trimethoprim/Sulfamethoxazole.
Store at temperatures not exceeding 30°C.
MIMS Class
ATC Classification
J01FA10 - azithromycin ; Belongs to the class of macrolides. Used in the systemic treatment of infections.
FC tab 500 mg x 3's.
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