Dexamethasone + Chloramphenicol

Uses

For steroid-responsive inflammatory ocular conditions for which a corticosteriod is used and where bacterial infection or a risk of bacterial ocular infection exists. For inflammatory conditions of the palpebral and bulbar conjunctiva, cornea and anterior segment of the globe where the inherent risk of steroid use in certain infective conjunctivitis is accepted to obtain a diminution in oedema and inflammation. For chronic anterior uveitis and corneal injury from chemical, radiation or thermal burns, or penetration of foreign bodies. It is also effective postoperatively.

Dexamethasone + Chloramphenicol is also used to associated treatment for these conditions: Acne, Bacterial Conjunctivitis, Bacterial Conjunctivitis caused by susceptible bacteria, Bacterial Infections, Bacterial dacryocystitis, Bacterial diarrhoea, Conjunctivitis allergic, Corneal Inflammation, Eye swelling, Keratitis bacterial, Ocular Inflammation, Trachoma, Anterior eye segment inflammation, Bacterial blepharitis, Bacterial corneal ulcers, Non-purulent ophthalmic infections caused by susceptible bacteria, Superficial ocular infections, Skin disinfectionAcne Rosacea, Acute Gouty Arthritis, Acute Otitis Externa, Acute Otitis Media, Adrenal cortical hypofunctions, Adrenocortical Hyperfunction, Alopecia Areata (AA), Ankylosing Spondylitis (AS), Anterior Segment Inflammation, Aspiration Pneumonitis, Asthma, Atopic Dermatitis (AD), Berylliosis, Bullous dermatitis herpetiformis, Bursitis, Chorioretinitis, Choroiditis, Congenital Adrenal Hyperplasia (CAH), Congenital Hypoplastic Anemia, Conjunctivitis, Conjunctivitis allergic, Corneal Inflammation, Cushing's Syndrome, Dermatitis, Dermatitis exfoliative generalised, Dermatitis, Contact, Diabetic Macular Edema (DME), Discoid Lupus Erythematosus (DLE), Drug hypersensitivity reaction, Edema of the cerebrum, Epicondylitis, Episcleritis, Erythroblastopenia, Eye Infections, Eye allergy, Eye swelling, Glaucoma, Hypercalcemia, Idiopathic Thrombocytopenic Purpura, Infection, Inflammation, Inflammation of the External Auditory Canal, Intraocular Inflammation, Iridocyclitis, Iritis, Keloid Scars, Leukemia, Acute, Lichen Planus (LP), Lichen simplex chronicus, Loeffler's syndrome, Macular Edema, Malignant Lymphomas, Middle ear inflammation, Mucosal Inflammation of the eye, Multiple Myeloma (MM), Muscle Inflammation caused by Cataract Surgery of the eye, Mycosis Fungoides (MF), Necrobiosis lipoidica diabeticorum, Noninfectious Posterior Uveitis, Ocular Infections, Irritations and Inflammations, Ocular Inflammation, Ocular Inflammation and Pain, Ocular Irritation, Ophthalmia, Sympathetic, Optic Neuritis, Otitis Externa, Pemphigus, Perennial Allergic Rhinitis (PAR), Phlyctenular keratoconjunctivitis, Post-traumatic Osteoarthritis, Postoperative Infections of the eyes caused by susceptible bacteria, Regional Enteritis, Rheumatoid Arthritis, Rheumatoid Arthritis, Juvenile, Sarcoidosis, Scleritis, Seasonal Allergic Conjunctivitis, Seasonal Allergic Rhinitis, Secondary thrombocytopenia, Serum Sickness, Severe Seborrheic Dermatitis, Stevens-Johnson Syndrome, Synovitis, Systemic Lupus Erythematosus (SLE), Trichinosis, Tuberculosis (TB), Tuberculosis Meningitis, Ulcerative Colitis, Uveitis, Vernal Keratoconjunctivitis, Acquired immune hemolytic anemia, Acute nonspecific tenosynovitis, Acute rheumatic carditis, Corticosteroid-responsive dermatoses, Ear infection-not otherwise specified caused by susceptible bacteria, Granuloma annulare lesions, Non-suppurative Thyroiditis, Ocular bacterial infections, Severe Psoriasis, Steroid-responsive inflammation of the eye, Varicella-zoster virus acute retinal necrosis, Watery itchy eyes

How Dexamethasone + Chloramphenicol works

Chloramphenicol is lipid-soluble, allowing it to diffuse through the bacterial cell membrane. It then reversibly binds to the L16 protein of the 50S subunit of bacterial ribosomes, where transfer of amino acids to growing peptide chains is prevented (perhaps by suppression of peptidyl transferase activity), thus inhibiting peptide bond formation and subsequent protein synthesis.

The short term effects of corticosteroids are decreased vasodilation and permeability of capillaries, as well as decreased leukocyte migration to sites of inflammation. Corticosteroids binding to the glucocorticoid receptor mediates changes in gene expression that lead to multiple downstream effects over hours to days.

Glucocorticoids inhibit neutrophil apoptosis and demargination; they inhibit phospholipase A2, which decreases the formation of arachidonic acid derivatives; they inhibit NF-Kappa B and other inflammatory transcription factors; they promote anti-inflammatory genes like interleukin-10.

Lower doses of corticosteroids provide an anti-inflammatory effect, while higher doses are immunosuppressive. High doses of glucocorticoids for an extended period bind to the mineralocorticoid receptor, raising sodium levels and decreasing potassium levels.

Dosage

Dexamethasone + Chloramphenicol dosage

1 or 2 drops is instilled into the affected eyes every 3 or 4 hours, or more frequently if deemed advisable by the prescribing physician. Administration should be continued day and night for the first 48 hours, after which the interval between applications may be increased. Treatment should be continued for at least 48 hours after the eye appears normal.

Side Effects

Adverse reactions seen with Chloramphenicol are transient ocular burning or discomfort. Other reported reactions include stinging, redness, itching, conjunctivitis/keratitis, periocular/facial edema, foreign body sensation, photophobia, blurred vision, tearing, dryness and eye pain.

Toxicity

Oral, mouse: LD₅₀ = 1500 mg/kg; Oral, rat: LD₅₀ = 2500 mg/kg. Toxic reactions including fatalities have occurred in the premature and newborn; the signs and symptoms associated with these reactions have been referred to as the gray syndrome. Symptoms include (in order of appearance) abdominal distension with or without emesis, progressive pallid cyanosis, vasomotor collapse frequently accompanied by irregular respiration, and death within a few hours of onset of these symptoms.

The oral LD₅₀ in female mice was 6.5g/kg and 794mg/kg via the intravenous route.

Overdoses are not expected with otic formulations. Chronic high doses of glucocorticoids can lead to the development of cataract, glaucoma, hypertension, water retention, hyperlipidemia, peptic ulcer, pancreatitis, myopathy, osteoporosis, mood changes, psychosis, dermal atrophy, allergy, acne, hypertrichosis, immune suppression, decreased resistance to infection, moon face, hyperglycemia, hypocalcemia, hypophosphatemia, metabolic acidosis, growth suppression, and secondary adrenal insufficiency. Overdose may be treated by adjusting the dose or stopping the corticosteroid as well as initiating symptomatic and supportive treatment.

Precaution

Dexamethasone and Chloramphenicol Eye drops must be used under strict medical supervision. Because of the possibility of inducing corneal abscess, fungal keratopathy or glaucoma the patient should be referred to an ophthalmologist if the eye has not responded within 48 hours.

Interaction

Decreased effects of iron and vitamin B12 in anaemic patients. Phenobarbitone and rifampin reduce efficacy of chloramphenicol. Impairs the action of oral contraceptives.

Drug interaction can be occurred with following drugs:Diuretics, cardiac glycosides, antidiabetics, NSAIDs, anticoagulants, antacids etc. Besides, if patients undergo long-term therapy of glucororticoids with concomitant salicylates, any reduction in glucocorticoid dosage should be made with caution, since salicylate intoxication has been reported in such cases.

Volume of Distribution

A 1.5mg oral dose of dexamethasone has a volume of distribution of 51.0L, while a 3mg intramuscular dose has a volume of distribution of 96.0L.

Elimination Route

Rapidly and completely absorbed from gastrointestinal tract following oral administration (bioavailability 80%). Well absorbed following intramuscular administration (bioavailability 70%). Intraocular and some systemic absorption also occurs after topical application to the eye.

Absorption via the intramuscular route is slower than via the intravenous route. A 3mg intramuscular dose reaches a C_max of 34.6±6.0ng/mL with a T_max of 2.0±1.2h and an AUC of 113±38ng*h/mL. A 1.5mg oral dose reaches a C_max of 13.9±6.8ng/mL with a T_max of 2.0±0.5h and an AUC of 331±50ng*h/mL. Oral dexamethasone is approximately 70-78% bioavailable in healthy subjects.

Half Life

Half-life in adults with normal hepatic and renal function is 1.5 - 3.5 hours. In patients with impaired renal function half-life is 3 - 4 hours. In patients with severely impaired hepatic function half-life is 4.6 - 11.6 hours. Half-life in children 1 month to 16 years old is 3 - 6.5 hours, while half-life in infants 1 to 2 days old is 24 hours or longer and is highly variable, especially in low birth-weight infants.

The mean terminal half life of a 20mg oral tablet is 4 hours. A 1.5mg oral dose of dexamethasone has a half life of 6.6±4.3h, while a 3mg intramuscular dose has a half life of 4.2±1.2h.

Clearance

A 20mg oral tablet has a clearance of 15.7L/h. A 1.5mg oral dose of dexamethasone has a clearance of 15.6±4.9L/h while a 3.0mg intramuscular dose has a clearance of 9.9±1.4L/h.

Elimination Route

Corticosteroids are generally eliminated predominantly in the urine. However, dexamethasone is 15

Pregnancy & Breastfeeding use

US FDA Pregnancy category C. There are no adequate and well-controlled studies in pregnant women. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Caution should be exercised when Dexamethasone ophthalmic solution is administered to a nursing woman.

Contraindication

It is contraindicated in fungal, viral, tuberculous and other infections of the eye and in glaucoma. It is also contraindicated in patients hypersensitive to any component of this product. The use of anti-infective and steroid is always contraindicated after uncomplicated removal of a corneal foreign body.

Special Warning

Safety and efficacy in pediatric patients have not been established.

Acute Overdose

If a rise of intraocular pressure occurs, the treatment has to be discontinued

Storage Condition

Store below 25° C preferably in a refrigerator; do not freeze, away from light. Keep out of reach of children.

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