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. |
| Molecular Weight | 360.44 |
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 | Avoid use during first trimester due to risk of cleft palate and other congenital anomalies from glucocorticoid exposure. |
| 2nd trimester | Use only if potential benefit justifies risk; may cause intrauterine growth restriction and adrenal suppression in fetus. |
| 3rd trimester | Use only if potential benefit justifies risk; prolonged use may result in neonatal adrenal suppression and low birth weight. |
Clinical note
Comprehensive clinical and safety monograph for PRED-G (PRED-G).
| Placental transfer | Prednisolone crosses placenta but is largely inactivated by 11-beta-hydroxysteroid dehydrogenase type 2. Gentamicin crosses placenta and may accumulate in fetal tissues. |
| Breastfeeding | Pred-G (prednisolone acetate and gentamicin) is likely compatible with breastfeeding. Prednisolone is excreted in low levels into breast milk; short-term use is considered safe. Gentamicin is poorly absorbed orally and unlikely to cause adverse effects in infants. However, monitor for potential gastrointestinal disturbances. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to prednisolone, gentamicin, or any component of the formulationUntreated bacterial, fungal, or viral infections (including herpes simplex keratitis)Administration by intravitreal injection (off-label route)
| 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 |
| Food/Dietary | None reported for ophthalmic use. |
| Clinical Pearls |
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| Lactation Rating | L2 (Safer) |
| 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. |
| 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. |
| PRED-G is a combination of prednisolone acetate (corticosteroid) and gentamicin (aminoglycoside antibiotic) used for ophthalmic inflammatory conditions with bacterial infection or risk of infection. Shake vigorously before each use. Do not use in viral, fungal, or mycobacterial ocular infections. Intraocular pressure should be monitored regularly with prolonged use. Avoid contamination of the dropper tip. Use with caution in patients with corneal thinning or glaucoma. |
| Patient Advice | Shake the bottle well before each use. · Wash hands before applying the drops. · Do not touch the dropper tip to any surface to avoid contamination. · Tilt head back, pull down lower eyelid, and apply the prescribed number of drops. · Close eyes gently for 1-2 minutes after instillation. · Do not use while wearing contact lenses unless directed by your doctor. · Report any vision changes, eye pain, or worsening redness immediately. · Complete the full course as prescribed; do not stop abruptly without consulting your doctor. · Keep out of reach of children. |