PRED-G
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRED-G (PRED-G).
Prednisolone acetate is a glucocorticoid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis; gentamicin sulfate is an aminoglycoside antibiotic that inhibits bacterial protein synthesis by binding to 30S ribosomal subunit.
| Metabolism | Prednisolone undergoes hepatic metabolism primarily via CYP3A4; gentamicin is excreted unchanged in urine. |
| Excretion | Renal excretion accounts for approximately 70% of elimination, with the remainder as unchanged drug in feces (20%) and biliary excretion (10%). |
| Half-life | The terminal elimination half-life of gentamicin (the active component) is approximately 2–3 hours in adults with normal renal function. In neonates, half-life is prolonged to 5–11 hours. The immunosuppressive component (prednisolone) has a half-life of 2–4 hours. |
| Protein binding | Gentamicin: less than 30% bound to plasma proteins. Prednisolone: approximately 70–90% bound to corticosteroid-binding globulin and albumin. |
| Volume of Distribution | Gentamicin: 0.2–0.3 L/kg, indicating distribution primarily into extracellular fluid. Prednisolone: 0.4–1.0 L/kg, reflecting extensive tissue distribution. |
| Bioavailability | Ophthalmic suspension: systemic bioavailability is minimal (<1%) due to small dose and rapid clearance, but can be higher if nasolacrimal occlusion is not used. |
| Onset of Action | Ophthalmic administration: Clinical effect typically observed within 2–4 hours following topical application to the eye. |
| Duration of Action | Duration of clinical effect for the antibiotic component is approximately 6–8 hours; for the corticosteroid, duration of anti-inflammatory activity is up to 24 hours, though clinical use recommends administration every 2–4 hours initially. |
1 drop of the ophthalmic suspension (containing prednisolone acetate 1% and gentamicin sulfate 0.3%) into the affected eye(s) every 2-4 hours during the day, then taper as clinical signs improve. For severe disease, 1 drop every hour initially.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | No systemic absorption occurs with ophthalmic use; thus, no renal adjustment is required. Gentamicin component may have renal effects if absorbed, but topical ocular use does not necessitate GFR-based modifications. |
| Liver impairment | No systemic absorption occurs; no adjustment required for hepatic impairment. |
| Pediatric use | Same as adult dosing: 1 drop of ophthalmic suspension into the affected eye(s) every 2-4 hours, tapering as response allows. Safety and efficacy established in children; no weight-based dosing necessary due to topical administration. |
| Geriatric use | No specific dose adjustment needed. Use same dosing as adults. Monitor for increased intraocular pressure (IOP) due to steroid component; elderly may be more susceptible to IOP elevation and cataract formation. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PRED-G (PRED-G).
| Breastfeeding | Systemic absorption following topical ophthalmic administration is negligible. Prednisolone is excreted into breast milk in low amounts; gentamicin is also excreted in low concentrations. The M/P ratio for prednisolone is approximately 0.5-2.0 (estimated from systemic use). Given the low ocular dose, it is considered compatible with breastfeeding. Monitor infant for gastrointestinal effects (gentamicin) and adrenal suppression (prednisolone) if prolonged use. |
| Teratogenic Risk | PRED-G (prednisolone acetate 1% and gentamicin sulfate 0.3% ophthalmic suspension) is classified as FDA Pregnancy Category C. Topical ophthalmic use results in minimal systemic absorption; however, corticosteroids are generally associated with an increased risk of cleft palate and intrauterine growth restriction when used systemically during the first trimester. Gentamicin has been associated with fetal ototoxicity and nephrotoxicity with prolonged systemic use. Overall risk from ophthalmic administration is considered low, but caution is advised. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to prednisolone, gentamicin, or any component","Epithelial herpes simplex keratitis (dendritic keratitis)","Vaccinia, varicella, and other viral infections of cornea/conjunctiva","Mycobacterial infections of eye","Fungal infections of ocular structures"]
| Precautions | ["Prolonged use may lead to ocular hypertension/glaucoma, optic nerve damage, cataract formation","May mask infection or promote secondary infection","Fungal infections should be considered in persistent corneal ulceration","Not for injection","Cross-sensitivity to other aminoglycosides possible"] |
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| Fetal Monitoring | Monitor intraocular pressure (IOP) in pregnant patients, especially with prolonged corticosteroid use. Assess for signs of secondary infection or corneal thinning. No specific fetal monitoring required beyond routine obstetric care, but observe for potential effects of systemic corticosteroid exposure (e.g., growth, glucose tolerance) if used extensively. |
| Fertility Effects | No direct evidence of fertility impairment from topical ophthalmic PRED-G. Systemic corticosteroids may transiently affect ovulation or spermatogenesis at high doses; however, ophthalmic use is unlikely to have significant impact. Gentamicin has no known effect on human fertility at typical doses. |