Pharmacotherapeutic group: corticosteroids and anti-infectives in combination, ATC code: S01CA01.
Dexamethasone:
The anti-inflammatory potency of dexamethasone is approximately 25 times greater than that of hydrocortisone. Like all anti-inflammatory corticosteroids, it inhibits phospholipase A2, the first step in prostaglandin synthesis, thereby preventing the formation of inflammatory mediators such as prostaglandins and leukotrienes. Dexamethasone also inhibits the chemotactic migration of neutrophils to the site of inflammation and reduces leukocyte count and activity.
Chloramphenicol:
Chloramphenicol is a low-molecular-weight, broad-spectrum bacteriostatic antibiotic. It is active against Gram-positive and Gram-negative bacteria, rickettsiae, and mycoplasmas. Its mechanism of action involves selective inhibition of bacterial protein synthesis.
Chloramphenicol is active against the following ocular pathogens: Staphylococcus aureus, streptococci including Streptococcus pneumoniae, Escherichia coli, Haemophilus influenzae, Klebsiella/Enterobacter species, Moraxella lacunata (Morax–Axenfeld bacillus), and Neisseria species. It is not sufficiently active against Pseudomonas aeruginosa or Serratia marcescens.
Resistance to chloramphenicol has been demonstrated in vitro and in vivo in strains of Staphylococcus, Salmonella, Shigella, E. coli, and Pseudomonas aeruginosa. Resistance is partly mediated by a plasmid-borne resistance factor. In vitro susceptibility testing performed on bacteria isolated from the ocular surface in patients with clinical symptoms, using various topical antibiotics, has shown that chloramphenicol exhibits the highest in vitro activity among the antibiotics tested and that resistance to chloramphenicol was the lowest.
⚠️ Warnings
Long-term treatment with chloramphenicol, including topical ocular use, may in very rare cases lead to bone marrow aplasia. The irreversible form may occur after a latent period of weeks or months.
Use of chloramphenicol is associated with a potential risk of aplastic anaemia or other blood dyscrasias. The product should be used only when alternative forms of therapy are ineffective and/or contraindicated.
Prolonged use may lead to secondary ocular infections or promote the development of resistant bacteria. Corticosteroids may mask, induce, or worsen ocular infection.
Long-term use of corticosteroids may cause a pathological rise in intraocular pressure. In predisposed patients and patients with glaucoma, intraocular pressure should be monitored regularly, particularly during long-term treatment.
Intensive, prolonged therapy may contribute to the development or worsening of posterior subcapsular cataract. The product should not be used for longer than 10 days unless otherwise directed by a physician.
In disorders causing thinning of the cornea or sclera, chronic use of corticosteroids is known to be capable of causing perforation. Caution is also required with concurrent use of topical corticosteroids such as dexamethasone and topical NSAIDs (non-steroidal anti-inflammatory drugs) (see section 4.5).
If no improvement is seen after three days of treatment, alternative treatment options should be considered.
Use of corticosteroids after cataract surgery may delay healing and increase the incidence of cyst formation.
Particular caution is required in patients with diabetes mellitus. These patients may be predisposed to elevated intraocular pressure and/or cataract formation.
In general, caution is required when administering corticosteroids to infants (aged 28 days to 3 months) and children under 2 years of age.
In predisposed patients, including children and patients treated with CYP3A4 inhibitors (including ritonavir and cobicistat), Cushing's syndrome and/or adrenal suppression associated with systemic absorption of ophthalmic dexamethasone may occur following intensive or prolonged continuous treatment. In such cases, treatment should be tapered gradually.
Visual disturbances
Visual disturbances may be reported with systemic and topical corticosteroid use. If a patient develops symptoms such as blurred vision or other visual disturbances, referral to an ophthalmologist should be considered for evaluation of possible causes, which may include cataract, glaucoma, or rare conditions such as central serous chorioretinopathy (CSCR), which has been reported following use of systemic and topical corticosteroids.
The use of contact lenses during ocular infection is not recommended, as it may promote the spread of microorganisms.
The eye drops are not intended for injection. They must never be administered subconjunctivally or directly into the anterior chamber of the eye.
Discontinuation of treatment after prolonged use should be carried out gradually, as with systemically administered corticosteroids.
