Azilab

Abacten is indicated for infections (caused by susceptible organisms) in lower respiratory tract infections including bronchitis and pneumonia, in upper respiratory tract infections including sinusitis and pharyngitis/tonsillitis, in otitis media, and in skin and soft tissue infections. In sexually transmitted diseases in men and women, Abacten is indicated in the treatment of non-gonococcal urethritis and cervicitis due to Chlamydia trachomatis.

Abacten is well tolerated with a low incidence of side-effects. Most side-effects observed were mild to moderate in severity. The majority of side-effects were gastrointestinal in origin with nauseas, abdominal discomfort (pain/cramps), vomiting, flatulence, diarrhoea and loose stools being occasionally observed. Allergic reactions such as rash or photosensitivity have occurred and there have also been rare reports of serious hypersensitivity reactions. Reversible elevations in liver transaminases have been seen with a frequency similar to the comparative macrolides and penicillins used in clinical trials. Rarely, cases of cholestatic jaundice have been observed. Transient mild reductions in neutrofil counts have occasionally been observed in clinical trials, although a causal relationship to azithromycin has not been established. Hearing impairment: In investigational studies where higher doses were used for prolonged periods of time, reversible hearing impairment was seen in some patients.

As with erythromycin and other macrolides, rare serious allergic reactions, including angioneurotic oedema and anaphylaxis, has been reported. Some of these reactions with azithromycin have resulted in recurrent symptoms and required a long period of observation and treatment.

Azithromycin is acid-stable and can therefore be taken orally with no need of protection from gastric acids. It is readily absorbed; its absorption is greater on an empty stomach. Time to peak concentration in adults is 2.1 to 3.2 hours for oral dosage forms. Due to the high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations of azithromycin are released. The concentration of azithromycin in the tissues can be over 50 times higher than in plasma. This is due to ion trapping and the high lipid solubility.
Azithromycin's half-life allows a large single dose to be administered and yet maintain bacteriostatic levels in the infected tissue for several days. Following a single 500 mg dose, plasma concentrations of azithromycin declined in a polyphasic pattern with a mean apparent plasma clearance of 630 mL/min and a terminal elimination half life of 68 hours. The prolonged terminal half-life is thought to be due to extensive uptake and subsequent release of drug from tissues. Biliary excretion of azithromycin, predominantly unchanged, is a major route of elimination. Over the course of a week, approximately 6% of the administered dose appears as unchanged drug in urine.
Microbiology: Azithromycin acts by binding to the 50S ribosomal subunit of susceptible microorganisms and, thus, interfering with microbial protein synthesis. Nucleic acid synthesis is not affected. Azithromycin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections:
Aerobic and facultative gram-positive microorganisms
: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes
Aerobic and facultative gram-negative microorganisms
: Haemophilus ducreyi, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae
Other microorganisms
: Chlamydia pneumoniae, Chlamydia trachomatis , Mycoplasma pneumoniae , Betalactamase production should have no effect on azithromycin activity.
Aerobic and facultative gram-positive microorganisms
: Streptococci (Groups C,F,G), Viridans group streptococci
Aerobic and facultative gram-negative microorganisms
: Bordetella pertussis, Legionella pneumophila
Anaerobic microorganisms
: Peptostreptococcus species, Prevotella bivia