Pharmacotherapeutic group: corticosteroids and anti-infectives in combination, ATC code: S01CA01. Dexamethasone:
The anti-inflammatory potency of dexamethasone is approximately 25 times 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 numbers and activity.
Chloramphenicol:
Chloramphenicol is a low-molecular-weight bacteriostatic antibiotic with a broad spectrum of activity. It is effective against Gram-positive and Gram-negative bacteria, rickettsiae and mycoplasmas. Its mechanism of action consists of 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 and Serratia marcescens.
Resistance to chloramphenicol has been demonstrated both 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 on bacteria isolated from the ocular surface of patients with clinical signs of infection, using various topical antibiotics, has shown that chloramphenicol exhibits the highest in vitro activity of the antibiotics tested and that resistance to chloramphenicol was the lowest.
⚠️ Warnings
Prolonged treatment with chloramphenicol, including topical ophthalmic application, may in very rare cases lead to bone marrow aplasia. The irreversible form may emerge after a latent period of weeks or months.
The 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.
Long-term use may lead to secondary ocular infections or promote the development of resistant bacteria. Corticosteroids may mask, induce or aggravate an ocular infection.
Long-term use of corticosteroids may cause pathological elevation of intraocular pressure. In predisposed patients and patients with glaucoma, intraocular pressure should be monitored regularly, particularly during prolonged treatment.
Intensive, long-term treatment may contribute to the onset or worsening of posterior subcapsular cataract. The product should not be used for more than 10 days unless otherwise directed by the physician.
In conditions causing thinning of the cornea or sclera, chronic use of corticosteroids is known to be capable of causing perforation. Caution is also required when topical corticosteroids such as dexamethasone are used concomitantly with topical NSAIDs (non-steroidal anti-inflammatory drugs) (see section 4.5).
If there is no improvement 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 (28 days to 3 months of age) and to 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 ocular dexamethasone may occur following intensive or prolonged continuous treatment. In such cases, treatment should be discontinued gradually.
Visual disturbances
Visual disturbances may be reported with systemic and topical corticosteroid use. If a patient presents with 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 diseases such as central serous chorioretinopathy (CSCR), which has been reported after the use of systemic and topical corticosteroids.
The use of contact lenses during an ocular infection is not recommended, as it may lead to 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 following long-term use should be carried out gradually, as for systemically administered corticosteroids.
