Azithromycin is a macrolide antibacterial with a broad and essentially bacteriostatic action against many Gram-positive and to a lesser extent some Gram-negative bacteria, as well as other organisms including Mycoplasmas spp., Chlamydiaceae, Rickettsia spp.,and spirochaetes. Azithromycin and other macrolides bind reversibly to the 50S subunit of the ribosome, resulting in blockage of the transpeptidation or translocation reactions, inhibition of protein synthesis, and hence inhibition of cell growth. Its action is predominantly bacteriostatic but high concentrations are slowly bactericidal against the more sensitive strains. Because macrolides penetrate readily into white blood cells and macrophages there has been some interest in their potential synergy with host defence mechanisms in vivo. It is active 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, Salmonella and Shigella spp. Azithromycin is also active against Chlamydia trachomatis and some opportunistic mycobacteria, including Mycobacterium avium complex. It has activity against the protozoa Toxoplasma gondii and Plasmodium falciparum.


Following oral administration about 40% of a dose of Azithromycin is bioavailable. 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. 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 is excreted in the urine. The terminal elimination half-life is about 68 hours.


Azithromycin (zithrox) has a wide spectrum of activity and may be used to treat a wide range of infections caused by the following susceptible organisms
(a) Gram positive: Streptococcus pneumoniae, Str. pyogenes, Staphylococcus aureus, Baccillus anthracis, Corynebacterium diptheriae and Clostridium spp.
(b) Gram negative: Neisseria menengitidis, N. gonorrhoeae, Moraxella catarrhalis, Bordetella spp, Listeria monocytogenes, Brucella spp, Haemophilus ducreyi, H. influenzae, Helicobacter pylori and Campylobacter jejuni.
(c) Others sensitive: Actinomyces spp, Chlamydia, rickettsias, Treponema pallidum, some mycoplasmas and mycobacteria.
Azithromycin may also be used as a component of regimens in the prophylaxis and treatment of opportunistic infections like Mycobacterium avium complex (MAC) and may be used for prophylaxis


Zithrox® is used in patients with various conditions including anthrax, actinomycosis, the prophylaxis of endocarditis, leptospirosis, listeriosis,  mouth infections, otitis media, pharyngitis, the prevention of perinatal streptococcal infections, rheumatic fever and infections in splenectomised patients and staphylococcal and streptococcal skin infections.


Adults: For infections due to susceptible organisms:
(Including otitis media, respiratory-tract and skin infections) The usual dose of Azithromycin is 500mg as a single dose daily for 3 days.
Alternatively, an initial  dose of 500mg may be followed by 250mg daily for a further 4 days.
For uncomplicated genital infections:
The equivalent of 1g of Zithrox® as a single dose. A  single dose of 2g may be given for uncomplicated gonorrhoea.
For prophylaxis of disseminated MAC infections:
Azithromycin 1.2g may be given once weekly.

Children: In children over 6 months of age, a single daily dose of Azithromycin 10mg/kg body-weight should be given once daily for 3 days.
Body Weight (Kg)                   Dose (mg)       Dose (mL)
upto15                 100             2.5
15-25                200               5.0
26-35                  300               7.5
36-45                 400             10.0
Above 45kg Zithrox®  Tablets should be used as per the Adult dose  schedule.


Precautions: Zithrox® should be avoided in those known to be hypersensitive to it, or those who have previously developed jaundice.  Zithrox® should be used with care in patients with existing liver disease or hepatic impairment.

Adverse Effects: Gastro-intestinal disturbances are the most frequent adverse effect but are usually mild and less frequent. Transient elevations of liver enzyme values have been reported and, rarely, cholestatic jaundice. Rashes, headache and dizziness may occur. Transcient alterations in neutrophil counts have been seen in patients receiving Azithromycin. It should not be used in patients with hepatic impairment.
Interactions: Concurrent administration of antacids containing aluminium or magnesium salts can reduce the rate, but not the extent, of absorption of Azithromycin. Increased rifabutin toxicity has been reported in patients receiving Azithromycin and rifabutin.

Store in a dry place below 25°C. Protect from light.  Keep all medicines out of the reach of children.

Prescription Only Medicine (POM)
®Regd. TM                                                       Ref. No.: INS108/01.08

  • ZITHROX®250 Tablets F/C

    PresentationLight yellow, circular, biconvex film coated tablet embossed 'COSMOS' on one side and plain on the other side. Each film coated tablet contains: Azithromycin Dihydrate USP equivalent to Azithromycin 250mg. Pack size - 6's

  • ZITHROX®500 Tablets F/C

    PresentationLight yellow, capsule-shaped film coated tablet embossed 'COSMOS' on one side and a breakline on the other side. Each film coated tablet contains: Azithromycin Dihydrate USP equivalent to Azithromycin 500mg. Pack size - 3's

  • ZITHROX® Dry Powder for Suspension

    PresentationPinkish White granular powder which on reconstitution forms a pink viscous suspension with cherry flavour. Each 5mL spoonful of the resultant suspension contains: Azithromycin Dihydrate USP equivalent to Azithromycin 200mg. Pack size - 15ml