CHLOROMYCETIN HYDROCORTISONE
Clinical safety rating: avoid
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
Chloromycetin (chloramphenicol) is a bacteriostatic antibiotic that inhibits protein synthesis by binding to the 50S ribosomal subunit, preventing peptide bond formation. Hydrocortisone is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2 and reducing prostaglandin and leukotriene synthesis.
| Metabolism | Chloramphenicol is metabolized primarily in the liver by glucuronidation via UDP-glucuronosyltransferases (UGTs) and also undergoes reduction to inactive metabolites. Hydrocortisone is metabolized in the liver via reduction and conjugation. |
| Excretion | Renal: ~80-90% of chloramphenicol as inactive metabolites (glucuronide conjugate) and 5-10% unchanged. Biliary: <3% of unchanged drug. Fecal: minimal. |
| Half-life | Chloramphenicol: 1.5-4 hours in adults with normal hepatic function; prolonged to 3-7 hours in neonates and up to 15 hours in severe liver disease. Hydrocortisone: 1-2 hours. |
| Protein binding | Chloramphenicol: ~50-80% bound primarily to albumin. Hydrocortisone: ~90% bound to corticosteroid-binding globulin (CBG) and albumin. |
| Volume of Distribution | Chloramphenicol: 0.6-1 L/kg, indicating wide distribution including CSF, bile, and aqueous humor. Hydrocortisone: 0.4-0.5 L/kg. |
| Bioavailability | Chloramphenicol: Oral ~80-90%; ophthalmic drops: negligible systemic absorption (<5%) with typical dosing. Hydrocortisone: Oral ~96%; ophthalmic drops: minimal systemic absorption (<1%). |
| Onset of Action | Ophthalmic: within 1-2 hours for chloramphenicol; hydrocortisone effects begin within 2-4 hours. Topical (otic): similar ophthalmic onset. |
| Duration of Action | Chloramphenicol: bacteriostatic levels persist for 6-8 hours after ophthalmic dose; systemic treatment every 6 hours. Hydrocortisone: anti-inflammatory effect lasts 4-8 hours after topical application. |
| Molecular Weight | Chloramphenicol: 323.13 Da; Hydrocortisone: 362.46 Da |
Apply 1-2 drops or a small amount (approximately 0.5 cm ribbon) into the affected eye(s) every 3-4 hours, or more frequently as needed. For severe infections, may be used every 2 hours. Not to exceed 6 times daily. Otic: Instill 3-4 drops into the affected ear(s) 2-3 times daily.
| Dosage form | FOR SUSPENSION |
| Renal impairment | No dose adjustment required for renal impairment as systemic absorption is minimal following topical ophthalmic or otic use. |
| Liver impairment | No dose adjustment required for hepatic impairment due to negligible systemic absorption. |
| Pediatric use | Children ≥2 years: Same as adult dosing. For younger children, use with caution and under medical supervision; dose should be based on severity of infection and body weight, typically 1 drop or small amount applied to affected eye(s) every 4-6 hours. |
| Geriatric use | Use with caution due to increased risk of adverse effects such as elevated intraocular pressure or cataract formation with prolonged use. No specific dose adjustment, but monitor intraocular pressure and corneal integrity regularly. |
| 1st trimester | Avoid; chloramphenicol crosses placenta and is associated with gray baby syndrome, though risk is low with short-term use. Hydrocortisone: avoid high doses due to possible increased risk of oral clefts. |
| 2nd trimester | Avoid; chloramphenicol may cause bone marrow suppression in fetus and neonate. Hydrocortisone: use only if clearly needed. |
| 3rd trimester | Avoid; chloramphenicol may cause gray baby syndrome in neonate. Hydrocortisone: prolonged use may lead to adrenal suppression in neonate. |
Clinical note
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
| FDA category | Positive |
| Placental transfer | Chloramphenicol readily crosses the placenta, achieving fetal serum concentrations 30-80% of maternal levels. Hydrocortisone crosses placenta; fetoplacental metabolism reduces active drug. |
■ FDA Black Box Warning
Chloramphenicol is associated with serious and fatal blood dyscrasias (aplastic anemia, bone marrow hypoplasia, thrombocytopenia, granulocytopenia). It should not be used for trivial infections or prophylaxis.
| Common Effects | adrenal insufficiency |
| Serious Effects |
Hypersensitivity to chloramphenicol or hydrocortisoneKnown or suspected viral infections (e.g., herpes simplex, vaccinia, varicella, ocular herpes)Fungal infections of the eye or surrounding structuresHistory of chloramphenicol-induced bone marrow suppression
| Precautions | Prolonged use may result in overgrowth of nonsusceptible organisms including fungi. Caution in patients with prior hypersensitivity reactions. Use with caution in hepatic impairment. Discontinue use if signs of bone marrow suppression occur. |
| Food/Dietary |
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| Breastfeeding | Chloramphenicol is excreted into breast milk and may cause bone marrow suppression or gray baby syndrome in nursing infants; avoid breastfeeding. Hydrocortisone is present in milk but generally considered compatible at low doses; however, combination product not recommended. |
| Lactation Rating | Avoid |
| Teratogenic Risk | Chloramphenicol crosses the placenta. First trimester: theoretical risk of gray baby syndrome; avoid. Second/third trimesters: associated with gray baby syndrome (cardiovascular collapse, cyanosis, death) in neonates; contraindicated. Hydrocortisone: increased risk of cleft palate (first trimester), fetal adrenal suppression (prolonged use). |
| Fetal Monitoring | Monitor maternal CBC, LFTs, bilirubin. Fetal ultrasound for growth restriction (hydrocortisone). Neonatal observation for signs of gray baby syndrome (pallor, cyanosis, hypothermia, abdominal distension) if exposure near term. |
| Fertility Effects | Chloramphenicol: no known effect on fertility. Hydrocortisone: may impair ovulation; no effect on spermatogenesis. |
| No significant food interactions reported for topical or ophthalmic use. Systemic chloramphenicol may be affected by food intake (absorption slightly delayed but not clinically significant). Avoid alcohol as it may cause disulfiram-like reaction with systemic chloramphenicol. |
| Clinical Pearls | Chloromycetin (chloramphenicol) is a bacteriostatic antibiotic that inhibits protein synthesis; combined with hydrocortisone for anti-inflammatory effect. Primarily used topically or ophthalmically due to risk of aplastic anemia with systemic use. Monitor for bone marrow suppression; avoid prolonged use. Not first-line for routine infections. |
| Patient Advice | Do not use this medication for longer than prescribed to avoid side effects. · Contact doctor immediately if you experience unusual bleeding, bruising, or signs of infection (fever, sore throat). · For eye or ear drops: avoid touching the dropper tip to any surface to prevent contamination. · Inform your doctor of all other medications you are taking, especially other antibiotics or corticosteroids. · Report any vision changes, eye pain, or worsening of symptoms. |