Dexamethasone/ Polymyxin B/ Neomycin

Registered South African indications:

• Acute or chronic non-purulent conjunctivitis
• Blepharoconjunctivitis
• Keratoconjunctivitis
• Non-specific superficial keratitis
• Deep keratitis
• Acne rosacea keratitis
• Iridocyclitis
• Mild acute iritis
• Recurrent marginal ulceration
• Corneal ulceration
• Non-purulent blepharitis
• Scleritis
• Episcleritis
• Scleroconjunctivitis
• Herpes zoster ophthalmicus
• Post-operative infection prophylaxis

Contraindications

• Hypersensitivity to the active ingredient or any of the excipients in this combination product
• Herpes simplex keratitis
• Vaccinia, varicella, and other viral infection of cornea or conjunctiva
• Fungal diseases of ocular structures
• Mycobacterial ocular infections

Cautions

• Pregnancy
• Breastfeeding
• Prolonged use
• Patients predisposed to raised intraocular pressure
• Intensive therapy
• Patient at risk of adrenal suppression
• Concomitant use of contact lenses
• Children
• May impair ability to drive and operate machinery

Forms avail. in SA and covered in this monograph: opd, oin

Acute or chronic non-purulent conjunctivitis
Blepharoconjunctivitis
Keratoconjunctivitis
Non-specific superficial keratitis
Deep keratitis
Acne rosacea keratitis
Iridocyclitis
Mild acute iritis
Recurrent marginal ulceration
Corneal ulceration
Non-purulent blepharitis
Scleritis
Episcleritis
Scleroconjunctivitis
Herpes zoster ophthalmicus
Post-operative infection prophylaxis

Dexamethasone/ Polymyxin B/ Neomycin
1mg/6000 IU/3500 IU (per ml)
1mg/6000 IU/3500 IU (per g)

• Ophthalmic (opd): Apply 1-2 drops into conjunctival sac(s), 4-6hrly
• Ophthalmic (oin): Apply small amount to affected conjunctival sac(s), 6-8hrly

Reduce dose when satisfactory improvement has been attained

Administer any other ophthalmic medicinal products at least 5min apart

See adult dosage

Pregnancy

• Caution
• There are no or limited amount of data from the use of dexamethasone/ polymyxin b/ neomycin (ophthalmic) in pregnant women
• Aminoglycoside antibiotics, such as neomycin, do cross the placenta after intravenous dosing in pregnant women. Non-clinical and clinical systemic exposure to aminoglycosides has been shown to induce ototoxicity and nephrotoxicity. At the low dose administered via this topical product, neomycin is not expected to cause ototoxicity or nephrotoxicity from in utero exposure. Prolonged or repeated corticoid use during pregnancy has been associated with an increased risk of intra-uterine growth retardation. Infants born of mothers who have received substantial doses of corticosteroids during pregnancy should be observed carefully for signs of hypoadrenalism
• Studies in animals with some active components of dexamethasone/ polymyxin b/ neomycin (ophthalmic) have shown reproductive  and not recommended in pregnancy

Breastfeeding

• Caution; not recommended
• It is unknown whether topical ophthalmic dexamethasone, neomycin or polymyxin B are excreted in human milk. Because systemic corticosteroids and aminoglycosides may be distributed into milk, a risk to the suckling child cannot be excluded. A decision must be made whether to discontinue/abstain from breastfeeding or to discontinue therapy with dexamethasone/ polymyxin b/ neomycin (ophthalmic) taking into account the benefit of breastfeeding for the child and the benefit of the product to the woman

Renal Impairment

• No dose adjustment recommended  

Hepatic Impairment

• No dose adjustment recommended

Elderly

• No dose adjustment recommended  

Porphyria Information

• Probably not porphyrinogenic (PNP)

Drugs in Sport

• Permitted - No warnings

Central Nervous System Disorders

• Headache

Endocrine and Metabolic Disorders

• Cushing's syndrome
• Adrenal suppression

Immune, Blood and Lymphatic System Disorders

• Hypersensitivity reaction

Sensory Disorders

• Keratitis
• Increased intraocular pressure 
• Photophobia
• Mydriasis
• Eyelid ptosis
• Eye pain
• Eye swelling
• Eye pruritus
• Ocular discomfort
• Foreign body sensation in eyes
• Eye irritation
• Ocular hyperaemia
• Increased lacrimation
• Blurred vision
• Corneal thinning

• Topical steroids
• Topical non-steroidal anti-inflammatory drugs
• CYP3A4 inhibitors
• Aminoglycosides

None routine. Specific cases may require

• Ophthalmic examination
• Intraocular pressure

Dexamethasone
Suppresses inflammation by inhibiting oedema, fibrin deposition, capillary leakage, and phagocytic migration during the inflammatory response. Glucocorticoids inhibit vascular endothelial growth factor, a potent promoter of vascular permeability.

Polymyxin B
Polymyxin B has a bactericidal action against almost all gram-negative bacilli, it interacts with the lipopolysaccharide of the cytoplasmic outer membrane of Gram-negative bacteria, altering membrane permeability and causing cell death. 

Neomycin
Neomycin is an aminoglycoside antibiotic which acts by binding to a specific protein on the 30S ribosomal subunit of the microbe. This results in faulty alignment or recognition with respect to mRNA and probably tRNA during initiation of microbial peptide chain formation. The mRNA is misread on the recognition region of the ribosome, resulting in the wrong amino acid being inserted into the peptide. This result in production of non-functional peptide chains.

COMBINATION PREPARATIONS

Dexamethasone/ Polymyxin B/ Neomycin

Eye drops (per ml)  1mg/6000 IU/3500 IU

• Maxitrol drops (Novartis South Africa) originator

Eye ointment (per g) 1mg/6000 IU/3500 IU

• Maxitrol Ointment (Novartis South Africa) originator