Apozyth is a medication prescribed to combat infections caused by susceptible organisms, with indications spanning several body systems. It is used for both lower respiratory tract infections, such as bronchitis and pneumonia, and upper respiratory tract infections, including sinusitis and pharyngitis/tonsillitis. Furthermore, it is effective against otitis media (ear infection) and various skin and soft tissue infections. In the realm of sexually transmitted diseases, Azithromycin is specifically indicated for treating non-gonococcal urethritis and cervicitis in both men and women when the cause is Chlamydia trachomatis.
Pharmacokinetics and Distribution of Azithromycin
Apozyth 500 mg Tablet is characterized by several pharmacological traits that enable its effective use in treatment. It possesses acid stability, meaning it can be consumed orally without needing specific protection from stomach acid. The drug is quickly absorbed, with maximal absorption achieved when the medication is taken on an empty stomach. Peak blood levels are reached between 2.1 and 3.2 hours after administration in adults.
A defining feature is the drug's remarkable tissue affinity. Azithromycin is actively delivered by immune cells (phagocytes) directly to the infection site. Consequently, its concentration within body tissues can exceed the level in the bloodstream by more than 50-fold, attributed to its high lipid solubility and a process called ion trapping.
This substantial tissue accumulation contributes to its extended terminal elimination half-life of 68 hours. This prolonged presence permits short-course or single-dose regimens, as bacteriostatic concentrations are maintained in the infected area for multiple days. While a small fraction (about 6%) is excreted unchanged in the urine over a week, the principal route of elimination for Azithromycin is biliary excretion (through bile)
Azithromycin's Microbial Action and Spectrum
Azithromycin exerts its antibacterial effect by specifically targeting the 50S ribosomal subunit within susceptible microorganisms. By binding to this subunit, the drug effectively disrupts microbial protein synthesis—a vital process—without affecting the production of nucleic acids.
Its proven effectiveness in both laboratory settings (in vitro) and clinical treatment covers a broad spectrum of bacteria:
★ Gram-Positive Organisms: This includes major pathogens like Staphylococcus aureus and key Streptococcus species (S. pneumoniae, S. pyogenes, S. agalactiae, and Viridans group streptococci).
★ Gram-Negative Organisms: It is active against bacteria such as Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, and Legionella pneumophila.
★ Atypical Pathogens: The drug is also effective against crucial atypical microbes, including Chlamydia pneumoniae, Chlamydia trachomatis, and Mycoplasma pneumoniae.
Notably, the effectiveness of Azithromycin is not compromised by the production of $beta$-lactamase enzymes by bacteria.
Oral Dosing Guidelines for Azithromycin
Antacids:
When azithromycin is used alongside antacids, dosing should be separated to avoid decreased absorption. The antibiotic should be taken at least one hour before or two hours after the antacid.
Carbamazepine:
Studies conducted in healthy volunteers have shown that taking azithromycin together with carbamazepine does not cause clinically meaningful changes in the blood levels of carbamazepine or its active metabolite.
Cyclosporin:
Some macrolide antibiotics are known to affect cyclosporin metabolism. Since comprehensive pharmacokinetic and clinical interaction data with azithromycin are limited, careful use is recommended when both drugs are prescribed together. If combined therapy is required, cyclosporin blood concentrations should be closely monitored and dosage adjustments made as needed.
Digoxin:
Certain macrolides may reduce the intestinal breakdown of digoxin in some individuals. As a result, concurrent administration of azithromycin and digoxin may lead to increased digoxin levels, and appropriate clinical monitoring is advised.
Ergot Derivatives:
Because of the risk of ergotism, azithromycin should not be administered together with medications containing ergot derivatives.
Methylprednisolone:
Clinical evaluations in healthy subjects have demonstrated that azithromycin does not significantly influence the pharmacokinetic profile of methylprednisolone.
Theophylline:
No pharmacokinetic interaction has been observed when azithromycin and theophylline are given together in healthy individuals. However, routine monitoring of theophylline concentrations remains advisable as standard practice.
Warfarin:
Pharmacodynamic studies indicate that azithromycin does not affect the anticoagulant action of a single 15 mg dose of warfarin in healthy volunteers. Although these drugs can be used concurrently, regular monitoring of prothrombin time (PT) should be maintained.
Terfenadine:
At the recommended dose of 60 mg every 12 hours, azithromycin did not alter the pharmacokinetics of terfenadine. Combined use did not produce clinically relevant effects on cardiac repolarization, as assessed by QTc interval measurements at steady state.
Contraindications
Apozyth 500 mg Tablet should not be used in patients with a known allergy to azithromycin or other macrolide antibiotics. Concomitant use with ergot derivatives is contraindicated. The drug is also not recommended for patients with existing hepatic disorders.
Apozyth 500 mg Tablet is generally well tolerated and is associated with a low frequency of adverse reactions. Most reported effects are mild to moderate in nature. Gastrointestinal symptoms are the most common and may include nausea, abdominal discomfort or cramps, vomiting, bloating, diarrhea, and loose stools, occurring occasionally.
Allergic responses such as skin rash or photosensitivity have been reported, along with rare instances of severe hypersensitivity reactions. Temporary increases in liver enzyme levels have been observed at rates similar to those seen with other macrolide antibiotics and penicillins in clinical studies. Rare cases of cholestatic jaundice have also been documented.
Clinical trials have noted occasional, mild, and reversible decreases in neutrophil counts, although a direct causal link to azithromycin has not been clearly established. In research studies involving higher doses used over extended durations, some patients experienced reversible hearing impairment.
Apozyth 500 mg Tablet is designated as a Pregnancy Category B medication. Findings from animal reproduction studies have not demonstrated any harm to the fetus following exposure to azithromycin. However, sufficient and well-controlled clinical studies in pregnant women are not available.
As results from animal studies may not reliably reflect outcomes in humans, azithromycin should be prescribed during pregnancy only when no appropriate alternative treatment options exist.
It has not been clearly established whether azithromycin passes into human breast milk. For this reason, careful consideration and caution are advised when administering azithromycin to breastfeeding mothers.
As observed with erythromycin and other macrolide antibiotics, rare but potentially serious hypersensitivity reactions, including angioedema and anaphylaxis, have been reported in association with azithromycin use.
Specific data regarding azithromycin overdose are not available. Symptoms commonly linked to excessive intake of macrolide antibiotics may include hearing disturbances, pronounced nausea, vomiting, and diarrhea.
Management of overdose should consist of gastric lavage when appropriate, along with supportive and symptomatic treatment measures.
Use in Renal Impairment:
Patients with mild renal impairment (creatinine clearance greater than 40 ml/min) do not require dosage adjustment. However, due to limited clinical data in individuals with moderate to severe renal dysfunction, azithromycin should be used cautiously in these patients.
Use in Hepatic Impairment:
As azithromycin is primarily eliminated through the liver, it should not be administered to patients with underlying hepatic disease.
Effects on Ability to Drive and Use Machines:
There is no evidence to suggest that azithromycin adversely affects the ability to drive vehicles or operate machinery.
Store in a cool and dry location, protected from direct light and excessive heat. Ensure the product is kept out of the reach of children.