METIMYD
Clinical safety rating: caution
Comprehensive clinical and safety monograph for METIMYD (METIMYD).
Metimyd contains sulfacetamide (a sulfonamide antibiotic) and prednisolone (a corticosteroid). Sulfacetamide inhibits bacterial dihydropteroate synthase, blocking folate synthesis. Prednisolone suppresses inflammation by binding glucocorticoid receptors, inhibiting phospholipase A2, and reducing prostaglandin and leukotriene synthesis.
| Metabolism | Sulfacetamide is metabolized via acetylation in the liver; prednisolone is primarily metabolized in the liver by CYP450 enzymes (e.g., CYP3A4). |
| Excretion | Primarily renal: approximately 70% unchanged drug excreted via glomerular filtration and tubular secretion; biliary/fecal elimination accounts for less than 10%. |
| Half-life | Sulfacetamide: terminal elimination half-life is 7–13 hours in adults with normal renal function; prolonged in renal impairment (up to 20–40 hours). |
| Protein binding | Sulfacetamide: 10–30% bound to plasma albumin. |
| Volume of Distribution | Sulfacetamide: approximately 0.3–0.4 L/kg; distributes into extracellular fluid and achieves therapeutic levels in ocular tissues. |
| Bioavailability | Ophthalmic solution: systemic absorption is minimal (<5%) due to local administration; oral bioavailability of sulfacetamide is approximately 100% but not clinically used. |
| Onset of Action | Ophthalmic solution: relief of symptoms within 30 minutes to 1 hour after instillation. |
| Duration of Action | Ophthalmic solution: clinical effect lasts 4–6 hours per dose; sustained use required for resolution of infection. |
| Molecular Weight | 360.36 |
1–2 drops into the conjunctival sac every 4 hours for 7–10 days; for severe infections, up to every 2 hours initially.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | No clinically significant renal elimination; adjustment not required based on GFR. |
| Liver impairment | Not studied; no adjustment recommended for Child-Pugh class A or B; use with caution in class C due to potential systemic accumulation. |
| Pediatric use | Children ≥2 years: 1–2 drops every 4 hours; for severe infection, every 2 hours initially. Safety in infants <2 years not established. |
| Geriatric use | No specific dose adjustment; use lowest effective dose due to possible increased sensitivity and reduced tear production. |
| 1st trimester | Avoid use during first trimester unless clearly needed; sulfonamides may cause jaundice in neonates when used near term. |
| 2nd trimester | Use with caution if benefit outweighs risk; no known teratogenicity from topical ophthalmic use. |
| 3rd trimester | Contraindicated near term due to risk of kernicterus in neonates from sulfonamide displacement of bilirubin. |
Clinical note
Comprehensive clinical and safety monograph for METIMYD (METIMYD).
| Placental transfer | Sulfonamides cross the placenta; prednisolone is metabolized by placental 11β-HSD2, reducing fetal exposure. |
| Breastfeeding | Systemic absorption from topical ophthalmic use is minimal; however, sulfonamides excreted in breast milk may cause hemolytic anemia in G6PD-deficient infants or kernicterus in jaundiced infants. Use with caution. |
■ FDA Black Box Warning
None explicitly stated in FDA labeling; however, corticosteroids may suppress immune response and increase risk of secondary infections. Sulfonamides may cause severe hypersensitivity reactions.
| Serious Effects |
Hypersensitivity to sulfonamides or corticosteroidsViral infections of the cornea (e.g., dendritic keratitis)Fungal infections of the eyeMycobacterial infections of the eye
| Precautions | Prolonged use may increase intraocular pressure (IOP) in glaucoma patients, Risk of secondary ocular infections (e.g., fungal, viral) due to immunosuppression, Corneal perforation in patients with corneal thinning, Sulfonamide hypersensitivity reactions including Stevens-Johnson syndrome, Systemic absorption may occur with prolonged use |
| Food/Dietary | No known food interactions. Avoid alcohol if concurrent corticosteroid systemic absorption is a concern, though minimal with ophthalmic use. |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C (FDA). Prednisolone acetate: increased risk of cleft palate with first-trimester exposure; risk of adrenal suppression in neonates with chronic maternal use. Sulfacetamide: no evidence of teratogenicity in animal studies; risk of kernicterus in third trimester due to bilirubin displacement. Avoid combination sulfonamides near term. |
| Fetal Monitoring | Monitor for maternal blood glucose elevation, blood pressure changes, signs of infection. Fetal monitoring for growth restriction and adrenal suppression with prolonged corticosteroid use. Assess neonatal bilirubin and signs of kernicterus if sulfacetamide used near term. |
| Fertility Effects | No specific studies on fertility effects in humans. Corticosteroids may impair spermatogenesis and ovulatory function; sulfacetamide has no known impact on fertility. |
| Clinical Pearls | METIMYD is a combination of prednisolone acetate and sulfacetamide. Use cautiously in patients with glaucoma; monitor intraocular pressure. Avoid prolonged use due to risk of steroid-induced cataracts and immunosuppression. Do not use in fungal or untreated bacterial infections. Shake well before use. |
| Patient Advice | Shake the bottle well before each use. · Wash hands before applying; avoid touching the dropper tip to any surface. · Do not wear contact lenses during treatment unless instructed by your doctor. · Report any eye pain, vision changes, or worsening redness immediately. · Complete the full course even if symptoms improve to prevent resistance. |