METIMYD

Clinical safety rating: caution

Comprehensive clinical and safety monograph for METIMYD (METIMYD).

How it works

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.

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for METIMYD (METIMYD).

Breastfeeding	Prednisolone: excreted in breast milk; M/P ratio ~0.3; low risk with maternal doses ≤30 mg/day. Sulfacetamide: excreted in breast milk; risk of kernicterus in jaundiced infants; American Academy of Pediatrics recommends caution. Use only if benefit outweighs risk.
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.

Warnings & precautions

■ 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.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to sulfonamides or prednisolone","Active viral infections (e.g., herpes simplex keratitis)","Fungal or mycobacterial ocular infections","Untreated purulent bacterial infections"]

Clinical Precautions

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"]

Clinical Tips & Counseling

Drug interactions

Loading safety data…

METIMYD

Clinical safety rating: caution

Comprehensive clinical and safety monograph for METIMYD (METIMYD).

How it works

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for METIMYD (METIMYD).

Breastfeeding	Prednisolone: excreted in breast milk; M/P ratio ~0.3; low risk with maternal doses ≤30 mg/day. Sulfacetamide: excreted in breast milk; risk of kernicterus in jaundiced infants; American Academy of Pediatrics recommends caution. Use only if benefit outweighs risk.
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.

Warnings & precautions

■ 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.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to sulfonamides or prednisolone","Active viral infections (e.g., herpes simplex keratitis)","Fungal or mycobacterial ocular infections","Untreated purulent bacterial infections"]